Temperature Probe (Chris Kipp, Audrey Benson)

Add approx. 5 mL of vinegar to the test tube.

Insert the temperature probe and begin taking readings.

Add a very small scoop of sodium bicarbonate.

Gently stir with thermometer until dissolved.

Record temp and observations. Did it feel warm/cold?

Part 2: Magnesium sulfate + Water

Fill about ⅓ of the test tube with water.

Insert the temperature probe and begin taking readings.

Add a scoop of magnesium sulfate.

Gently stir with thermometer until dissolved.

Record temp and observations. Did it feel warm/cold?

Part 3: Calcium chloride + Water

Fill about ⅓ of the test tube with water.

Insert the temperature probe and begin taking readings.

Teacher will add calcium chloride.

Gently stir with thermometer until dissolved.

Record temp and observations. Did it feel warm/cold?

Data:

Use the temperature probe to gather temperature data for each reaction. Use these graphs to answer the questions.

Analysis:

Which reactions were endothermic?

Which reactions were exothermic?

Use evidence to support your answers.

Sample Investigation 1:

Abstract: Determine the molar enthalpy of the reaction between baking soda and vinegar.

Materials: baking soda, vinegar, 100mL beaker, temperature probe, graduated cylinder, balance

Procedure:

1. Use a graduated cylinder to measure out 50.0mL of 5% vinegar into a 100mL beaker.

2. Use a balance to measure out 2.0g of baking soda.

3. Place the temperature probe into the vinegar and start the data collection.

4. Add the baking soda to the vinegar and swirl to dissolve.

5. After the mixture has stopped reacting, end the data collection.

6. Clean and dry the temperature probe. Pour the mixture in the sink. Clean and dry the beaker.

Data:

Your data will be the graph generated by the temperature probe software.

Calculations

1. Calculate the change in temperature the mixture underwent during the reaction using the beginning and endpoints from your graph.

2. Calculate which chemical, the vinegar or the baking soda, was the limiting reagent in your reaction.

3. Calculate the molar enthalpy of the reaction according to the number of moles of the limiting reagent used in the reaction.

Conclusion: The molar enthalpy of the reaction between baking soda and vinegar is __________j/mol.

Sample Data & Analysis and Interpretation

This graph shows the temperature decreasing from 21C to 16C over a period of about 37s. The decrease means that this is an endothermic reaction, or a reaction that absorbs heat.

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