Entropy Lab

This lab will go in your lab book. Follow the directions below to complete the lab.

Purpose: (put into lab book)

• The purpose of this lab is to study entropy and enthalpy in chemical reactions.

Background: (put into lab book the answers to the following questions)

• Define enthalpy and entropy.

• List three factors that would cause a change in entropy.

The rest of the lab is divided into four parts. Start each part on a new page in your lab notebook!

Part 1: Combustion of Ethanol (start on a new page!)

Procedure: (summarize the procedure in your lab notebook)

1. Click here to watch the video.

2. Record observations (include color, phase, and temp changes) in data table.

Data: (copy into your lab book)

Conclusion:

(Answer the following questions in your lab book. Be sure to show your work for the math questions. You DO NOT need your purple sheet, a list of values can be found at the bottom of this page.)

• 1. In this part, ethanol gas (C₂H₆O) has combined with oxygen to produce carbon dioxide and water vapor. Write a complete balanced equation (including phase tags) for the reaction that has occurred.

  2. Based on what you observed, is this an endothermic or exothermic reaction? Explain.

  3. Calculate the enthalpy of this reaction.

  4. Based on your calculation, is this an endothermic or exothermic reaction? Explain.

  5. Based on the reaction you wrote, did the reaction move toward order or disorder? Explain.

  6. Calculate the entropy of this reaction.

1. Based on your calculation, did the reaction move toward order or disorder? Explain.

Part 2: Elementary School Volcano (start on a new page!)

Materials: (read the procedure below and list at least 5 different materials you will need, chemicals and glassware count)

Procedure: (summarize the procedure in your lab notebook)

1. Weigh out 5 g of sodium bicarbonate and pour it into a 50 mL beaker.

2. Measure out 10 mL of acetic acid in a graduated cylinder and measure its initial temperature.

3. Add it to the 50 mL beaker.

4. Measure the new temperature.

5. Record observations in data table.

6. ONLY IF YOU ARE ABSENT: Click here to watch the video.

Data: (copy into your lab book)

Conclusion:

(Answer the following questions in your lab book. Be sure to show your work for the math questions. You DO NOT need your purple sheet, a list of values can be found at the bottom of this page.)

1. In this part, sodium bicarbonate and acetic acid react to produce sodium acetate, carbon dioxide gas and liquid water. Write the complete balanced equation (including phase tags).

2. Based on what you observed, is this an endothermic or exothermic reaction? Explain.

3. Calculate the enthalpy of this reaction.

4. Based on your calculation, is this an endothermic or exothermic reaction? Explain.

5. Based on the reaction you wrote, did the reaction move toward order or disorder? Explain.

6. Calculate the entropy of this reaction.

7. Based on your calculation, did the reaction move toward order or disorder? Explain.

Part 3: Penny in Acid (start on a new page!)

Procedure: (summarize the procedure in your lab notebook)

• 1. Click here to watch the video.

  2. Record observations in data table. Note: When this reaction takes place, the test tube gets hot.

Data: (copy into your lab book)

Conclusion:

(Answer the following questions in your lab book. Be sure to show your work for the math questions. You DO NOT need your purple sheet, a list of values can be found at the bottom of this page.)

• 1. In this part, copper (penny) reacted with nitric acid. The products of the reaction are copper(I) nitrate solution, liquid water, and nitrogen dioxide gas. Write a complete balanced equation (including phase tags) for the reaction that has occurred.

  2. Based on what you observed, is this an endothermic or exothermic reaction? Explain.

  3. Calculate the enthalpy of this reaction.

  4. Based on your calculation, is this an endothermic or exothermic reaction? Explain.

  5. Based on the reaction you wrote, did the reaction move toward order or disorder? Explain.

  6. Calculate the entropy of this reaction.

  7. Based on your calculation, did the reaction move toward order or disorder? Explain

Part 4: Cold Pack (start on a new page!)

Materials: (read the procedure below and list at least 5 different materials you will need, chemicals and glassware count)

Procedure: (summarize the procedure in your lab notebook)

• 1. Measure out 20 mL of water using a graduated cylinder and measure its initial temperature.

  2. Add it to the 50 mL beaker.

  3. Weigh out 2.5 g of ammonium chloride and add it to the water.

  4. Stir with the thermometer as you measure the new temperature.

  5. Record observations in data table.

1. ONLY IF YOU ARE ABSENT: Click here to watch the video.

Data: (copy into your lab book)

Conclusion:

(Answer the following questions in your lab book. Be sure to show your work for the math questions. You DO NOT need your purple sheet, a list of values can be found at the bottom of this page.)

The products of this dissolving reaction are aqueous ions as shown in the reaction below:

• 1. Based on what you observed, is this an endothermic or exothermic reaction? Explain.

  2. Calculate the enthalpy of this reaction.

  3. Based on your calculation, is this an endothermic or exothermic reaction? Explain.

  4. Based on the reaction you wrote, did the reaction move toward order or disorder? Explain.

  5. Calculate the entropy of this reaction.

  6. Based on your calculation, did the reaction move toward order or disorder? Explain.

H and S values needed for the lab: