Category Archives: Chemistry Laboratory

Outline for a High School Chemistry Class

Need to complete a high school chemistry class with a wet lab? We did and that is how this blog was born. To help you get started, we have put together an overview of a high school chemistry course with links to posts about the lessons and labs.

I. Getting a High School chemistry lab kit.

We chose the The Home Scientist for our hands-on chemistry lab kit.

Of those offered, we used the CK01A Standard/Honors Home School Chemistry Laboratory Kit

The kit comes with most of the equipment and chemicals you need for a high school chemistry wet lab that you can do at home. It also comes with a free .pdf manual to download with complete, extensive lab instructions. (Link on this page). You will have to supply some materials, which are common household items for the most part. You will also need a place to store the chemicals away from small children and pets.

II. Choosing a High School Chemistry Textbook:

The text we used was Introductory Chemistry (4th Edition) by Nivaldo J. Tro. The book the textbook reading assignments in the lessons refer to that text. We chose this text over the Essentials version because it has three additional chapters at the end which could be used as reference material. We used chapters 1-16.

As typical with the textbook industry, there is now a newer edition.

Introductory Chemistry (5th Edition) by Nivaldo J. Tro

We liked the tone of the text and the great illustrations.

Another text that is commonly used in high school chemistry classrooms is:

Chemistry by Steven S. Zumdahl and Susan A. Zumdahl

Want more information? Don’t forget to check the links in the Online Chemistry Textbooks page and our Choosing a Chemistry Textbook post from the beginning of the class, which has more options.

III. High School Chemistry Class Outline

The following are links to the blog posts we used for the class. I split some of the chapters in the Tro text, so we ended up meeting for 22 weeks.

I have left out the sidebars, which were posts about some more information on questions the students found interesting.

Keeping a Chemistry Laboratory Notebook

Lesson 1: Introduction to Chemistry

Lab 1 Density of Liquids: Soft Drinks and Water

Lesson 2: Measurement and Problem Solving

Lab 2 Density of Solids and Measurement Challenge

Lesson 3: Matter

Lab 3: Separation of Mixtures

Lesson 4: Energy

Lab 4: Heat Capacity

Lesson 5: Atoms and Elements

Lab 5: Chemistry Unleashed

Lesson 6: Molecules and Compounds

Lab 6: What we did

Lesson 7: Calculating Chemical Composition

Lab 7: Finding Moles and Molecules

Lesson 8: Chemical Reactions Part 1

Lab 8: From Topic I, Recrystallization and Salting Out

Sidebar: Lab 8 Update

Lesson 9: Classifying Chemical Reactions

Lab 9: Topic III, Classifying Chemical Reactions

Lesson 10: Quantities in Chemical Reactions

Lab 10: Double Displacement Reactions

Lesson 11: The Electromagnetic Spectrum

Lab 11: Photochemistry

Lesson 12: Electrons, Atom Models, and the Periodic Table

(Note: For the lab, we did models of atom orbitals using Model Magic modeling clay. Let me know in the comments if you would like details.)

Lesson 13: Chemical Bonding

Lab 13: Conductance of Ionic and Molecular Solutes

Lesson 14: Gases

Lab 14: Gas Properties and Laws

Lesson 15: Properties of Liquids and Solids

Lab 15: Viscosity and Other Physical Properties of Liquids

Lesson 16: Solutions

Lab 16: Solubility and Solutions

Lesson 17: Acids and Bases

Lab 17: Investigating pH
Lesson 18: Rates of Chemical Reactions

Lab 18: Chemical Kinetics

Lesson 19: More About Rates of Chemical Reactions

Lab 19: Effect of Catalysts on Reactions

Lesson 20: Oxidation and Reduction

Lab 20: Sweet Redox Reactions for National Chemistry Week

Lab 21: Electrochemistry

For Lab 22, we had a review with activities and tasks from throughout the course.

outline-for-high-shcool-chemistry-course-homeschool

If you would like to know more about any of the materials or coursework, please feel free to leave questions in the comments.

Lab 21: Electrochemistry

Experimental Title: Lab 21:  Electrochemistry

Date of laboratory:  October 28, 2014

Purpose: The purpose of this laboratory is to investigate electrolysis of water and to produce electricity via a chemical reaction in a lemon battery.

Introduction:

Electrochemistry is the relationship between chemical energy and electrical energy. If you would like to learn more, be sure to review the second half of chapter 16 in your textbook.

Electrochemistry involves two separate processes:

1. Utilizing electrical energy to cause a chemical reaction to occur. An example is electrolysis, during which electricity is used to split water into oxygen and hydrogen gas.

The reaction for the electrolysis of water is
2H20 → O2 + 2H2

test-tubes

2. Using a chemical reaction to produce electricity. An example is a lemon battery, which can be used to produce enough electricity to light up a LED (Light emitting diode).

Check out this animation showing the movement of electrons between zinc and copper in a galvanic cell (Takes a few seconds to load.) A similar reaction takes place within the lemon.

How to make a lemon battery:

See the Hila Website for more instructions for making a lemon battery.

Special safety concerns for Lab 21:

  • If anything spills, please clean it up immediately with a paper towel and let your instructor know.
  • If glass breaks, do not pick it up with your bare hands. Notify your instructor immediately.
  • Be sure to wash your hands when you are finished with this lab
  • Avoid touching the battery with wet hands and don’t touch both terminals at once to avoid shocks.

Materials:

  • Magnesium sulfate (Epsom salts)
  • 9 Volt battery
  • Battery adapter
  • Glass beaker
  • 2 test tubes
  • Water
  • Graduated cylinders
  • Transfer pipette
  • Rubber band
  • Stoppers
  • Wood splint
  • Matches or butane lighter
  • Lemons
  • Zinc
  • Copper
  • Wires
  • LED (Light emitting diode)
  • Spatula (measuring)

Procedures:

Part 1.  Electrolysis of Water

1. Obtain a 250 mL glass beaker, 9 volt battery,  2 test tubes, magnesium sulfate, a rubber band, and the batter adapter with wire leads.

2. Add about 200 mL of water to the glass beaker. Add a heaping spatula full of magnesium sulfate to the water. Stir until it is dissolved.

3. Place the two glass test tubes side-by-side. Wrap with a rubber band to hold them in place.

4. Over the sink, fill the test tubes with the magnesium sulfate solution, trying to prevent bubbles from forming. Stopper the tubes with rubber stoppers.

5. Invert the tubes into the beaker and remove the stoppers, keeping the tubes submerged. If you have difficulty manipulating the stoppers in the beaker, try putting your thumb over a single filled test tube (like we did last time) and then transfer the tube into the beaker and release so the open end is submerged and no bubbles are trapped in the top. Hold the tube upright and repeat with the second tube.

6. Have a helper hold the tubes while you run the leads of the battery adapter into each test tube, red into one and black into the other. Do not submerse the adapter itself.

7. Connect the 9 volt battery to the adapter part. Pay attention to which ends are in which test tubes.

Observations:

8. Remove the battery when one test tube is filled with gas. Stopper each test tube under water to preserve the gases inside.

Optional:  Take the test tubes outside with the wood splint and lighter. For the tube with less gas in it, light the splint and then blow it out. Place the glowing splint near the opening of the tests tube and release the stopper.

What does this show?

Now, light another splint and hold it near the opening of the test tube with more gas, and remove the stopper. Note:  be prepared for a pop sound, so don’t be startled.

Part 2.  Lemon Battery

We will follow the instructions in the above video and website (linked in the introduction section) to put together and test a lemon battery.

Conclusions:

Once you have completed the parts, sit down and write a sentence or two to explain the results.

Discussion:

Record any thoughts you have about the experiments, including:

  • Possible improvements to the procedures or how to tweak techniques
  • How the results differed from your expectations
  • Suggestions for other experiments

Please leave a comment or send an e-mail if you have any questions before our meeting.

 

Lab 20: Sweet Redox Reactions for National Chemistry Week

In honor of National Chemistry Week 2014, let’s do some redox reactions using something sweet.

Experimental Title: Lab 20: Reduction-Oxidation Reactions

Date of laboratory:  October 21, 2014

Purpose: The purpose of this laboratory is to evaluate redox reactions.

Introduction:

Part 1: Permanganate Changes Color with Oxidation State

Sometimes it is possible to determine the oxidation state of a substance by looking at its color.

In a basic solution with small amounts of sugar added, permanganate ion is reduced to manganate ion:
MnO4– + e → MnO42–
and the solution changes from deep purple to deep green in color.
When there is excess sugar, the manganate is reduced to MnO2.
MnO42– + 2H2O + 2e → MnO2 + 4OH–
MnO2 is yellowish brown at the low concentrations, which is the final color change. This reaction is commonly called the “chameleon reaction” because many intermediate colors are often seen as the reaction progresses.

Here is a video that shows the reaction (you might want to turn down your speakers before playing it).

Part 2. Redox titration to find the relative amount of Vitamin C (ascorbic acid) in different foods

In this reaction, iodine oxidizes ascorbic acid to dehydroascorbic acid as it is reduced to iodide ions.
ascorbic acid + I2 → 2 I− + dehydroascorbic acid

Once all the ascorbic acid has been oxidized, the excess iodine is free to react with the starch indicator, forming the blue-black starch-iodine complex.

Special safety concerns for Lab 20:

  • Please use gloves and eye protection when handling hazardous materials.
  • If an acid spills, cover it with baking soda as we discussed. If a base such as NaOH spills, neutralize it with vinegar. If either spills on your skin, immediately wash with water.
  • If anything else spills, please clean it up immediately with a paper towel and let your instructor know.
  • If glass breaks, do not pick it up with your bare hands. Notify your instructor immediately.
  • Be sure to wash your hands when you are finished with this lab.

Materials:

  • Distilled water
  • Transfer pipettes
  • Sodium hydroxide
  • Sugar (granulated)
  • Glass beaker
  • Potassium permanganate, 0.1 M
  • Plastic cup
  • Starch indicator solution
  • Iodine
  • Orange juice
  • Cranberry juice
  • Red pepper juice
  • Lemon juice
  • Strawberry juice

Procedures:

Part 1. Permanganate Changes Color with Oxidation State

  1. Fill a glass beaker with 100 mL distilled water.
  2. Add 1 small spatula of granulated sugar and mix with stirring rod.
  3. Using the transfer pipette, add 0.5 mL sodium hydroxide.
  4. Using a clean pipette, add 0.5 mL of potassium permanganate.

Observations:

Note:  If the reaction does not proceed completely to yellowish-brown after about 10 minutes, try adding another spatula full of sugar.

 

Part 2. Perform a REDox Titration to Determine the Relative Amounts of Vitamin C (Ascorbic Acid) In Different Foods

1. Add 5 mL of distilled water to a plastic cup. Add 0.5 mL of starch indicator and stir. Draw up iodine in a transfer pipette and add one drop to the solution (Set the filled pipette in a clean cup). Swirl the solution. It should turn blue-black, indicating the presence of iodine. This shows you the color you should achieve at the endpoint of titration. Now add a few mL of orange juice to see what happens.

Observations:

2. Set up empty plastic cups for each type of juice. Predict which juices will contain the most Vitamin C (ascorbic acid) and thus require the most drops of iodine to reach the endpoint (turn blue-black).

Predictions:

Most vitamin C (ascorbic acid): _________________

2nd:__________________

3rd:___________________

4th:____________________

Least vitamin C: _____________

3. Add 5 mL of orange juice to a clean, empty cup. Add 0.5 mL of starch indicator. Draw up iodine into a pipette or use the pipette you filled previously. Carefully add iodine a drop at a time, counting the drops. Swirl after adding each drop and check to see if the solution has reached the titration endpoint (turned blue-black). Once the solution remains blue-black, record the number of drops of iodine you added.

Number of drops:

4. Repeat step 3 for the remaining types of juice.

Number drops for:

  • Cranberry juice:
  • Red pepper juice:
  • Lemon juice:
  • Strawberry juice:

Did your results match your predictions?

lemon

 

Conclusions:

Once you have completed the two parts, sit down and write a sentence or two to explain the results of each part.

Discussion:

Record any thoughts you have about the experiments, including:

  • Possible improvements to the procedures or how to tweak techniques
  • How the results differed from your expectations
  • Suggestions for other experiments
  • What key concepts you learned about redox reactions

Please leave a comment or send an e-mail if you have any questions before our meeting.

Lab 19: Effect of Catalysts on Reactions

Last time we looked at how concentration, temperature and surface area can influence rates of reaction. For this lab, we are going to determine the effects of catalysts on reaction rates.

Reading:  The Home Scientist Lab Topic VI. Session VI-2, pp. 114- 117.

Important note:  we will be using yeast as a source of catalase rather than blood. Please make that change as you write out the procedure in you notebook!

Experimental Title: Lab 19:  Effect of Catalysts on Reaction Rates

Date of laboratory:  October 14, 2014

Purpose: The purpose of this lab is to examine the effects of various catalysts on the rates of reactions.

Introduction:

For this lab, we will speed up the reaction of hydrogen peroxide breaking down into oxygen and water by adding catalase enzyme from yeast. We’ll stop the reaction by adding sulfuric acid to denature the catalase and then titrate the resulting solutions with a dilute solution of potassium permanganate to determine how much unreacted hydrogen peroxide remains in each sample.

In the presence of hydrogen peroxide, MnO4- ions are quickly reduced to Mn2+ ions, and the solution remains a light brown color. As soon as permanganate ions are slightly in excess, the solution assumes a purple color. By determining
the amount of permanganate required to change color, we can calculate the amount of hydrogen peroxide that remains in the samples.

Important equations:
2 H2O2(aq) → 2 H2O(l) + O2(g)

5 H2O2(aq) + 2 MnO4-(aq) + 6 H+(aq) → 2 Mn2+(aq) + 8 H2O(l) + 5 O2(g)

 Hydrogen-peroxide-3D-balls

(Public domain illustration of hydrogen peroxide from Wikimedia)

Special safety concerns for Lab 19:

  • Please use goggles and gloves.
  • If anything spills, please clean it up immediately with a paper towel and let your instructor know.
  • If glass breaks, do not pick it up with your bare hands. Notify your instructor immediately.
  • Be sure to wash your hands when you are finished with this lab

Materials: Include the list on page 114, but substitute yeast for blood.

Procedures:

Write the procedure on pages 115- 116 in your notebooks, substituting “yeast” for blood or “meat juice.”

_____________________

We will also look at a few other catalyzed reactions, but you won’t need to include these in your notebook unless you want to do so.

Materials:
◦    Copper II sulfate solution
◦    Clear plastic cup
◦    Salt
◦    Aluminum foil
◦    Thermometer
◦    Plastic spoon
Procedure:

  1.    Place the piece of aluminum foil in an empty cup. Use your fingers to push the foil firmly down so that it lays flat and covers the bottom of the cup.
  2.     Add 5 mL of the copper II sulfate solution to the cup with the aluminum foil.
  3.     Gently swirl the solution for a few seconds and let it stand still. Watch the aluminum for any bubbling or color change.
  4. Carefully place a thermometer in the cup and record the temperature.
  5.  Use your plastic spoon to place a small amount of salt in the copper II sulfate solution. Gently swirl the solution for a few seconds and let it stand still. Watch for any bubbling or color change.
  6.  Carefully place a thermometer in the cup and record the temperature.

If we have time, we’ll also look at iron (III) chloride as a catalyst for hydrogen peroxide, and a reaction between zinc and sulfuric acid.

_________________________

Conclusions:

Once you have completed the lab, sit down and write a sentence or two to explain the results.

Discussion:

Record any thoughts you have about the experiments, including:

  • Possible improvements to the procedures or how to tweak techniques
  • How the results differed from your expectations
  • Suggestions for other experiments
  • What key concepts you learned about catalysts

Please leave a comment or send an e-mail if you have any questions before our meeting.

 

Lab 18: Chemical Kinetics

For our lab this week we are going to look at some of the different ways to speed up reactions, as discussed in Lesson 18. We will be using our old friends sodium bicarbonate (baking soda) and vinegar, but this time we will quantify the rates of reactions. If we have time, we will see how changing the identity of one of the reactants changes the rate, as well.

Please read The Home Scientist pp. 106-113. We will be doing Session VI-1, pp. 108-113.

Experimental Title: Lab 18:  Determining the Effect of Temperature, Concentration, and Surface Area on Reaction Rates

Date of laboratory:  September 30, 2014

Purpose: The purpose of this lab is to determine the effect of temperature, concentration and surface area on reaction rates of acetic acid and sodium bicarbonate.

Introduction:

Please read the introduction to this topic on pp. 106-107 and the background on pp. 108-109.

The equation for the reaction is:

NaHCO3 + CH3COOH → CH3COONa + CO2 + H2O

To make sure the reaction runs to completion, we want a large excess of acetic acid so we’ll use 25 mL for each test run.

Special safety concerns for Lab 18:

  • If anything spills, please clean it up immediately with a paper towel and let your instructor know.
  • If glass breaks, do not pick it up with your bare hands. Notify your instructor immediately.
  • Be sure to wash your hands when you are finished with this lab

Materials:

See page 108.

Procedures: We will do parts I, II, and III on pp. 109-112. Please write the procedures in your notebooks.

Conclusions:

Once you have completed the three parts, sit down and write a sentence or two to explain the results of each part.

Discussion:

Record any thoughts you have about the experiments, including:

  • Possible improvements to the procedures or how to tweak techniques
  • How the results differed from your expectations
  • Suggestions for other experiments
  • What key concepts you learned about rates of reactions

Please leave a comment or send an e-mail if you have any questions before our meeting.

 

Lab 17: Investigating pH

We encounter acids and bases every day. Let’s find out more about them by doing some experiments.

Experimental Title: Lab 17:  Acids, Bases, and pH Indicators

Date of laboratory:  September 23, 2014

Purpose: The purpose of this laboratory is to investigate the use of pH indicators.

Introduction:

pH is a measurement of how basic or acidic a solution is based on the activity of hydronium ions (See lesson 17 for a discussion of acids and bases).

Certain molecules and substances change color when exposed to specific acidic or basic conditions, and thus can be used as pH indicators. There are over 150 different molecules that are used as pH indicators (see the excerpt from Handbook of Acid-Base Indicators by R. W. Sabnis at the bottom of this page). Examples of naturally-occurring pH indicators include litmus (a molecule extracted from certain lichens), anthocyanin (derived from red cabbage or berries), and curcumin (found in turmeric).

The pH value or range at which the pH indicator changes color is called the transition. Here are some of the known transitions:

Methyl red is red below a pH of 4.4 and yellow above 6.2. Methyl orange is red below a pH of 3.1 and orange/yellow above 4.4. Phenolthalien is pink in the range from 8.2 to 12.0. Thymol blue is red below 1.2, yellow from 2.8-8.0 and blue above pH 9.6. Turmeric is yellow/orange below 7.4 and red above 8.6.

 

Special safety concerns for Lab 17:

  • We will be using some strong acids and bases, so please bring and wear your goggles, gloves, long pants and closed-toe shoes.
  • If an acid spills, cover it with baking soda as we discussed. If a base spills, neutralize it with vinegar. If either spills on your skin, immediately wash with water.
  • If glass breaks, do not pick it up with your bare hands. Notify your instructor immediately.
  • Be sure to wash your hands when you are finished with this lab.

Materials:

  • Centrifuge tubes
  • Sharpie markers
  • Red cabbage
  • Blender
  • Distilled water
  • Acetic acid, 6M
  • Ammonia, 6M
  • Hydrochloric acid, 6M
  • Sodium hydroxide, 6M
  • Methyl red indicator
  • Methyl orange indicator
  • Phenolthalein
  • Thymol blue
  • Turmeric
  • Paper towels
  • Rubbing alcohol
  • Litmus paper
  • Wide range pH paper
  • 250 mL glass beaker
  • 100 mL graduated cylinder
  • Clear plastic cups
  • Household substances to test for pH

Procedures:

Note: I will prepare the red cabbage indicator and turmeric in advance using these simple steps:  For the red cabbage indicator, grind up fresh red cabbage in small batches with distilled water in a blender and then strain it in a colander to remove the bigger plant bits. For the turmeric, mix a little turmeric spice (used in curries) and rubbing alcohol in a small container and then dip in strips of paper towel. Allow the strips to dry (Protect the work surface, as turmeric stains).

Part 1. Acid and Base Standards

(Edit:  changed the numbering on Monday)

1. Label four centrifuge tubes, “0.1 M acetic acid”, “0.1 M ammonia”, “0.1 M hydrochloric acid”, and “0.1 M sodium hydroxide”. Place the tubes in the tray provided.
2. Measure 10 mL of distilled water to each of the four centrifuge tubes.
3. Using a pipette, transfer 0.25 mL of 6 M acetic acid to the “0.1 M acetic acid” centrifuge tube. Add additional distilled water to bring the total volume in
the tube to 15 mL. Cap the tube and swirl it gently to mix the contents.
4. Repeat that procedure in step 3 for each of the remaining centrifuge tubes, transferring 0.25 mL each of the 6 M ammonia, 6M hydrochloric acid, and 6M sodium hydroxide solutions. Be very careful and attend to any spills immediately.
5. Obtain a 24-well reaction plate and place it in the tray. Transfer 1.0 mL of 0.1 M acetic acid from the centrifuge tube into each well from A1 through A6. Recap the tube.
6. Transfer 1.0 mL of 0.1 M ammonia into each well from B1 through B6. Recap the tube.
7. Transfer 1.0 mL of 0.1 M hydrochloric acid into each well from C1 through C6. Recap the tube.
8. Transfer 1.0 mL of the 0.1 M sodium hydroxide into each well from D1 through D6. Recap the tube.

24-well-reaction-plate-template

Part 2. pH Indicators

Now we will test each type of pH indicator.

Part 2A:
1. Place 4 strips of wide-range pH paper on the lid of the 24-well plate. Using a stirring rod, obtain a drop of the fluid in well A1, acetic acid. Transfer it to a strip of pH paper. Allow the solution to react with the paper long enough so that it is no longer changing color. Record the final color and the pH that corresponds to that color in your notebook. Be sure to rinse the stirring rod carefully between samples.
2. Repeat step 1 completely, using the stirring rod to obtain a drop of the fluid in well B1, ammonia, and placing it on a strip of pH paper. Record the final color and the pH that corresponds to that color in your notebook.
3. Repeat step 1 completely, using the stirring rod to obtain a drop of the fluid in well C1, hydrochloric acid, and placing it on a strip of pH paper. Record the final color and the pH that corresponds to that color in your notebook.
4. Repeat step 1 completely, using the stirring rod to obtain a drop of the fluid in well D1, sodium hydroxide, and placing it on a strip of pH paper. Record the final color and the pH that corresponds to that color in your notebook.

Part 2B:
Now repeat part 2A using strips of red and blue litmus paper. Record your results.

Part 2C:
Repeat part 2A using the turmeric strips. Record your results.

Part 2D:
Add one drop of red cabbage indicator to each of the wells in column 2, A2 through D2. Look for color changes. If the changes are not conclusive, add another drop. Record the final color.

Part 2E:
Add one drop of methyl red to each of the wells in column 3, A3 through D3. Look for color changes. If the changes are not conclusive, add another drop. Record the final color.

Part 2F:
Add one drop of methyl orange to each of the wells in column 4, A4 through D4. Look for color changes. If the changes are not conclusive, add another drop. Record the final color.

Part 2G:
Add one drop of thymol blue to each of the wells in column 5, A5 through D5. Look for color changes. If the changes are not conclusive, add another drop. Record the final color.

Part 2H:
Add one drop of phenolthalein to each of the wells in column 6, A6 through D6. Look for color changes. If the changes are not conclusive, add another drop. Record the final color.

Now you have some idea what the range of pH values the pH indicators indicate. Keep these in the tray to use for comparison to household substances later.

 

Part 3. Phenolthalein “Titration”

Chemists use titration to determine the concentration of unknown solutions. Generally, doing a titration requires a burette, a piece of equipment that measures volume very accurately. Because we do not have access to a burette, we will simulate the process with a micropipette.

1. Place 50 mL of distilled water in a glass 250mL beaker using a 100 mL graduated cylinder.

2. Add 3 drops of phenothalein with a micropipette.

3. Using a clean micropipette, add drops of the 0.1 M ammonia from the centrifuge tube, stirring after each addition. Keep going until the solution turns pink and stays pink. Record the volume of ammonia you added.

4. Using a clean micropipette, add drops of 0.1 M acetic acid from the centrifuge tube, stirring after each addition. How much acetic acid is needed to make the solution go clear again?

 

Part 4. Determining the pH of common, household substances

Review Table 14.7 on page 507 in your textbook. We are going to check the pH of some common substances and create a similar table.

Leave space in your notebook for a table like this:

pH-table

Place substances in clear plastic cups provided. Test the pH with strips as we did in part 2 and then think about which indicator substances might verify your results. Mix indicator substances into the substances in clear cups. Try to find the transitions/color ranges for the red cabbage indicator. Record your results and the final pH values or ranges you obtain. We will compare our results.

Conclusions:

Once you have completed the four parts, sit down and write a sentence or two to explain the results of each part.

Discussion:

Record any thoughts you have about the experiments, including:

  • Possible improvements to the procedures or how to tweak techniques
  • How the results differed from your expectations
  • Suggestions for other experiments
  • What key concepts you learned about acids and bases

Excerpt from Handbook of Acid-Base Indicators by R. W. Sabnis:

Please leave a comment or send an e-mail if you have any questions before our meeting.

 

Lab 16: Solubility and Solutions

For this week we will be going back to the Home Scientist labs.

Reading:  Topic II. Solubility and Solutions. We will be doing Session II-1. Solubility as a Function of Temperature  pp. 42-52.

Experimental Title: Lab 16:  Solubility as a Function of Temperature

Date of laboratory:  September 16, 2014

Purpose: The purpose of this laboratory is to examine solubility of solid solutes as a function of temperature.

Introduction:

Go ahead and read through his introduction, pp. 42- 45, which covers some of the same things as the lesson and text readings. Briefly summarize the background information from the lab as for your own lab notebook introduction. The background information can be found on pp. 46-47.

Special safety concerns for Lab 16:

  • If anything spills, please clean it up immediately with a paper towel and let your instructor know.
  • If glass breaks, do not pick it up with your bare hands. Notify your instructor immediately.
  • Be careful with the hot solution.
  • Be sure to wash your hands when you are finished with this lab

Materials: See lists page 46.

Procedures:

You will find the process is somewhat similar to the recrystallization lab we did earlier. To help speed things up, I will be doing some of the preparation work for you ahead of time.

Part I. The synthesis of sodium carbonate, page 48 – 49:  I will do this at home and bring the sodium carbonate to lab already prepared. Go ahead and start with part II in your lab notebook, but be aware that we are working with washing soda and not baking soda.

Part II. Calibrate your thermometer.

There will be a laptop so we can check the local barometric pressure and use theonline-calculator.

Part III. Determine the solubility of sodium carbonate

We have the electronic scale, so we don’t need to worry about the conversions he lists in the note at the bottom of page 50. You can skip that part.

Note:  Several time he says “stir gently with the thermometer.” Please use a stirring rod instead.

Be sure to leave room in your notebook for the graph. It should look something like this:

solubilty-graph

Conclusions:

Once you have completed the lab, sit down and write a sentence or two to explain the results.

Discussion:

Record any thoughts you have about the experiments, including:

  • Possible improvements to the procedures or how to tweak techniques
  • How the results differed from your expectations
  • Suggestions for other experiments
  • What key concepts you learned

 

SMM_teasolubility

(Image public domain)
Please leave a comment or send an e-mail if you have any questions before our meeting.

Lab 15: Viscosity and Other Physical Properties of Liquids

Liquids have a number of interesting physical properties, such as viscosity and surface tension. Keep in mind that differences in these properties are largely due to differences in the intermolecular forces explained in Lesson 15, but length of molecules may also be a factor. For example, long molecules may change viscosity due to molecular entanglement.

Experimental Title: Lab 15:  Physical Properties of Liquids

Date of laboratory:  September 9, 2014

Purpose: The purpose of this laboratory is to investigate three physical properties of liquids:  surface tension, viscosity (including the special case of thixotropy), and evaporation.

Introduction:

Surface tension is the tendency of the molecules in liquids to interact with each other in such a way to pull together to minimize surface area. This inward pulling is due to cohesive forces.

Viscosity is how much the molecules in a liquid resist flow. Thixotropy is when certain gels or fluids are viscous (resistant to flow) under static conditions and then become less viscous when shaken, stirred or agitated.

Viscosity has a number of real world applications:

  • Food scientists study the viscosity of foods, such as the how viscous a given batch of strawberry jam is.
  • Health professionals check the viscosity of a patient’s blood.
  • Volcanologists monitor the viscosity of molten rock or magma
    to determine how easily a volcano will erupt.
  • Auto mechanics calculate the viscosity of oil needed for different engines and climates.
  • Artists pick paints for different projects based on their viscosity.

Evaporation or vaporization is a liquid changing into a gaseous state. The rate of evaporation is influenced by the strength of intermolecular forces, as well as temperature and surface area. A drop in temperature may also be an indication that a liquid is evaporating rapidly.

Special safety concerns for Lab 15:

  • If anything spills, please clean it up immediately with a paper towel and let your instructor know.
  • If glass breaks, do not pick it up with your bare hands. Notify your instructor immediately.
  • Alcohol is highly flammable, so keep it away from heat sources.
  • Be sure to wash your hands when you are finished with this lab

Materials:

  • Bowl
  • Plastic bins
  • Water
  • Graduated cylinders
  • Metal paper clips
  • Plexiglass sheet
  • Ketchup
  • Plastic chopstick for stirring
  • Dropper
  • Stand
  • Plastic cylinders
  • Glass marbles
  • Stopwatch.
  • Large bottle of light-colored shampoo
  • Sharpie marking pen
  • Rulers
  • Hot water (hot water from a faucet is fine)
  • Ice cubes
  • Paper towels
  • Thermometer
  • Temperature probe
  • Tissue
  • Rubbing alcohol
  • Calculator
  • Laundry detergent
  • Corn syrup
  • Vegetable oil

Procedures:

Note:  Today you can do the parts in any order, so go ahead to another part and come back to finish if you need to do so. No need to wait for materials.

Part 1. Determine the surface tension of water and other liquids

  1. Obtain a bowl and partially fill it with tap water.
  2. Take a metal paper clip and devise a way to float it on the surface of the water via surface tension.
  3. Answer the following questions:  How many paperclips can the surface tension hold? Does the shape of the paperclip affect its floating ability?
  4. Obtain another liquid. Using the floating metal paper clip test, compare the surface tension of that liquid to water.

Observations:

Part 2. A. Determine the viscosity of Various Liquids

1. Obtain four plastic cylinders. If there are no lines, draw a line as a starting point about 3 cm below the top of each cylinder and and a second line as a stopping point at least 3 cm above the blue part (to allow marbles to accumulate in the bottom for each run) with a Sharpie marking pen. You don’t want the ending line to be right at the bottom of the cylinder because the marble will slow down as it approaches the bottom. With the ruler, measure and record the distance between the lines in cm.

Length between marks (fall distance):

2. If the tubes provided are not already filled, fill one each with:

  • Tap water
  • Corn syrup
  • Vegetable oil
  • Laundry detergent

3. You or the helper should hold a marble at the surface of one of the liquids. The other person should zero out the stopwatch.

4. The person holding the stopwatch should say “Go!” and have the other person drop the marble. As the marble passes the starting point, which was marked in the previous section, the person holding the stopwatch should start the stopwatch. As the marble passes the ending point, which was marked in the previous section, the person holding the stopwatch should stop it.

5. Record the time elapsed in a data table. Leave the marble in the tube until the end of the trial.

6. Repeat steps 3-5 of this section, with the same liquid and cylinder four more times with four other marbles. When you have recorded the results, tip the fluid back into the original container and retrieve the marbles to wash before using with the next liquid.

7. Repeat the process for all the liquids.

viscosity-liquids-table

Note:  Technically in this experiment you are calculating velocity = distance/time rather than viscosity. Hawaii Space Grant has a more in depth viscosity experiment,  which includes calculating viscosity using this equation:

where

  • delta p = difference in density between the sphere and the liquid
  • g = acceleration of gravity
  • a = radius of sphere
  • v = velocity

Part 2. B. Investigate the effect of Temperature on Viscosity

1. Draw two lines as start and stop points all the way around the side of the shampoo bottle (about 3 cm from each end) with a Sharpie marking pen. (You don’t want the ending line to be at the bottom of the shampoo bottle because the marble will slow down as it approaches the bottom.) With the ruler, measure and record the distance between the lines in cm.

Length between marks (fall distance):
2. Uncap the bottle and insert a marble. Fill the bottle to the top with shampoo from another bottle. Take the temperature of the shampoo with the thermometer. Close the cap tightly.

Temperature of room temperature shampoo:

3. Turn the bottle upside down and observe the marble as it sinks downward. The marble should come to rest in the cap. This ensures that the marble will drop down the center of the bottle when it is inverted once more.

4. Invert the bottle once more and use the stopwatch to measure the time it takes for the marble to sink down the center of the bottle from the top line to the bottom line. Record the time.

5. Repeat step 4 four more times, for a total of five time measurements. Then calculate the average time it takes the marble to sink through the shampoo.

6. Next, investigate the viscosity of shampoo at a warmer temperature. Fill a bin with hot water from the faucet. Tighten the cap on the shampoo-filled bottle so it cannot leak. Then lay the bottle in the bin so it is completely covered. The hot water bath will heat up the shampoo. Leave the bottle in the hot water for about 1o minutes. Carefully rotate the bottle every five minutes with tongs to heat the shampoo evenly. Open the cap and take the final temperature of the shampoo with the thermometer.

Temperature of heated shampoo:

7. Repeat step 4 five times and record the data. Then calculate the average time it takes the marble to sink in warm shampoo.

8. Now cool the shampoo. Fill the bin provided with cold water and ice cubes and lay the bottle of shampoo on its side in the bin. Leave the bottle in the cold water for about 1o minutes. Carefully rotate the bottle every five minutes or so to cool the shampoo evenly. Open the cap and take the temperature with the thermometer.

Temperature of cold shampoo:

9. Repeat step 4 five times and record the data. Then calculate the average time it takes the marble to sink in cold shampoo.

shampoo-table

Part 2. C. Investigate the thixotropic Behavior of Ketchup

Remember all those commercials showing people struggling to get ketchup to come out of to bottle? Ever wonder why that is the case?

We will be investigating the question:  which is more viscous (thicker), undisturbed ketchup in the container or vigorously-stirred ketchup?

1. Look for two plastic cups labelled “undisturbed ketchup” and “stirred ketchup.” Take the plastic chopstick and stir the ketchup labelled “stirred ketchup” vigorously for at least one minute.

2. Using a dropper, gently suck up a sample from each type of ketchup and place approximately 0.5 mL dots on the piece of plexiglass as indicated. Tip the sheet of plexiglass upright against the wall in the tray provided. Record the distance each sample has moved after one minute and after five minutes.

ketchup-spots

ketchup-table

Part 3. Evaporation

 

1. Obtain the temperature probe. Wrap the probe in a small amount of tissue and then dip it into a sample of tap water. Record the initial temperature and the temperature at one minute, two minutes and three minutes.

2. Remove the wet tissue. Dry the probe and then wrap in a small amount of tissue as before. Now dip the wrapped probe in a sample of rubbing alcohol. Record the initial temperature and the temperature at one minute, two minutes and three minutes.

Compare your results.

evap-table

 

Conclusions:

Once you have completed the five parts, sit down and write a sentence or two to explain the results of each part.

Discussion:

Record any thoughts you have about the experiments, including:

  • Possible improvements to the procedures or how to tweak techniques
  • How the results differed from your expectations
  • Suggestions for other experiments
  • What key concepts you learned about the physical properties of liquids

We’ll go over the key concepts together at the end of lab.

Please leave a comment or send an e-mail if you have any questions before our meeting.

Lab 14: Gas Properties and Laws

For a change of pace this week we are going to do a series of activities and record our results and observations. After we are done, we are going to figure out how the gas properties and laws we learned from the lesson apply to our observations.

Experimental Title: Lab 14:  Investigation Into The Gas Laws

Date of laboratory:  Sept 2, 2014

Purpose:  The purpose of this laboratory is to examine air pressure, Boyle’s Law, Charles’s Law, and the Ideal Gas Law.

Introduction:

  1. Boyle’s Law relates pressure and volume
  2. Charles’s Law relates volume and temperature
  3. Avogadro’s Law relates volume and moles
  4. Ideal Gas Law combines these laws into the formula PV = nRT, where R is the constant 0.0821 L-atm/mol-K

Materials:

  • Empty soda can
  • Wire mesh
  • Stove
  • Oven mitts
  • Tongs
  • Ice
  • Bowl to hold ice water
  • Glass bottles or flasks
  • Wine vacuum pump with rubber stopper
  • Water balloons
  • Regular latex balloons
  • Boiled egg
  • Matches
  • Strip of paper
  • Food coloring
  • Metric ruler
  • Tap water
  • Pipette, thin stem
  • Beaker
  • Textbooks, hardcover, 6–8
  • Clamp
  • Sharpie pen
  • Measuring tape
  • Hair dryer
  • Hand boiler
  • Kitchen scale

Special safety concerns for Lab 14:

  • If anything spills, please clean it up immediately with a paper towel and let your instructor know.
  • If glass breaks, do not pick it up with your bare hands. Notify your instructor immediately.
  • Be extra careful when handling the open flame and the boiling hot water in the can on the stove.
  • Please be sure to wear goggles for the pop can (I) and egg and a bottle (III) as the containers will be under pressure.
  • Wash your hands when you are finished with this and any other lab.

Procedures:

I. “Pop” Can
1. Set the wire mesh on the burner of the stove and turn the temperature to “high.”
2. Add a small amount of water to an empty soda can, to a depth of about 1 cm.
3. Place the can upright on the burner and heat it until the water boils and steam flows out of the top opening.
4. Using oven mitts, remove the steaming can from the hot plate with tongs.
5. Invert the soda can into an ice-water bath.

Record your results and observations:

II. Balloons in a Bottle

1. Place one small water balloon filled with air and one small water balloon filled with water in the bottle provided.
2. Cap with the gray rubber seal provided.
3. Weigh the bottle.
Mass in grams:

4. Use the white wine vacuum to apply a vacuum to the bottle.

Weight the bottle again. Record your results and observations, especially comparing the air-filled versus the water-filled balloon:

5. Remove the gray stopper.

Record your results and observations:

III. Egg and a Bottle
1. Obtain a bottle or flask and a boiled egg (shell removed).
2. Light a strip of paper on fire with matches and quickly drop into the jar/flask.
3. Place the boiled egg on top.

Record your observations:

IV. Pressure on a Pipette (from Flinn Scientific)

Edit: I have removed the instructions, as they were from Flinn. You can find them as a free .pdf here.

Edit: Here is video of how to do this technique.

Number of Books             Length of air column in mm
0
1
2
3
4
5

Graph your results.

balloons1

Balloons by Teodoro S Gruhl

V. Balloon Expansion and Contraction

1. Blow up a standard latex balloon.
2. Mark a line around the middle (approximate equator) using a ruler and sharpie pen. Measure the circumference of the balloon with the measuring tape  at the line.
Circumference of balloon at room temperature:

3. Place the balloon in the freezer for about 10 minutes. Pull it out and immediately measure the circumference again.

Circumference of cold balloon:

4. Heat the balloon with a hair dryer. Measure the circumference again.

Circumference of heated balloon:

As Mr. Anderson pointed out in the video in lesson 14, you could take the temperature of each balloon and use the information to calculate absolute zero. Cool! (I couldn’t help that)

VI. Hand Boiler

1. Obtain the hand boiler. Warm it with your hands.

Observations:

Conclusions:

Once you have completed the experiment and cleaned up, sit down and write a sentence or two to explain the results. It is always a good idea to do this part while the experiment is fresh in your mind.

Discussion:

Record any thoughts you have about the experiments, including:

  • Possible improvements to the procedures or how to tweak techniques
  • How the results differed from your expectations
  • Whether the goals were met
  • Suggestions for other experiments

Please leave a comment or send an e-mail if you have any questions before our meeting.

Lab 13: Conductance of Ionic and Molecular Solutes

This week we are going to investigate the movement of cations and anions through solutions.

Reading:  The Home Scientist Lab Manual Topic II. Session II-2. Conductance of Ionic and Molecular Solutes, pp. 53-59.

Experimental Title: Lab 13:  Conductance of Ionic and Molecular Solutes

Date of laboratory:  August 26, 2014

Purpose: The purpose of this laboratory is to investigate the conductivity of distilled water, tap water, plus solutions of strong and weak acids, strong and weak bases, ionic salts and a molecular compound.

Introduction:

Read the background to the experiment on pp 53-55.

Briefly explain conductivity and resistivity. Write the equations for the reactions in your notebooks.

Special safety concerns for Lab 13:

  • This week the most hazardous materials are the 6M ammonia, 6M acetic acid, 6M hydrochloric acid, and 6M sodium hydroxide. Please use gloves and goggles at all times when handling these materials. (MSDS for 6M Ammonia, MSDS for 6M Acetic Acid, MSDS for 6M Hydrochloric Acid, and MSDS for 6M sodium hydroxide.
  • Remember to cover spills of acids with baking soda and spills of bases with vinegar.
  • If a chemical spills on you, wash it off immediately. Be especially careful when handling the multimeter probes!
  • Be sure to wash your hands very carefully when you are finished with this lab.

Materials:  See list page 53.

Procedures:

I will do Part I (boiling the distilled water) for you before lab. You don’t need to write it in your notebook, but be aware why boiling of the distilled water was necessary.

Write down the procedures for Part II and Part III  on pages 56-58 in the lab manual. Be sure to leave room for the data table to record your results. I will bring graph paper to graph your results, if you need it.

Template for the 24-well reaction plate:

24-well-reaction-plate-template

 

Conclusions:

Once you have completed the experiment and cleaned up, sit down and write a sentence or two to explain the results. It is always a good idea to do this part while the experiment is fresh in your mind.

Discussion:

Record any thoughts you have about the experiments, including:

  • Possible improvements to the procedures or how to tweak techniques
  • How the results differed from your expectations
  • Whether the goals were met
  • Suggestions for other experiments
  • The answers to the review questions he provides on page 59.

Please leave a comment or send an e-mail if you have any questions before our meeting.