Question: Does the number of steps in a reaction process affect the enthalpy change of the overall reaction?

Hypothesis:

To compare experimental data to functionality of Hess's Law.

Procedure:

Part A:

1. Write the reaction for the dissociation of solid sodium hydroxide in water.

2. Get a coffee cup calorimeter, tare the electronic scale, and weight the calorimeter. Record.

3. Add approximately 100.0mL of distilled water to the cup.

4. Re-weigh the cup to determine the volume of water. Record.

5. Obtain a small piece of aluminum foil, place it on the scale, and tare the scale.

6. Weigh out approximately 1.00g of NaOH pellets. (USE EXTREME CAUTION! Re-cap the bottle!) Record.

7. Measure the temperature (to TWO decimal places) of water in the cup. Record.

8. Add the pre-weighed NaOH pellets to the calorimeter with water, cap it, stir the contents, and measure the temperature (to TWO decimal places) every 15 seconds for 2 minutes (or more, as needed until temperature stops increasing). Record.

9. Clean up.

Part B:

1. Write the equation for reaction between aqueous sodium hydroxide and aqueous hydrochloric acid.

2. Using the designated graduated cylinders, obtain 50.0mL of each of 0.500M NaOH_(aq) and0.500M HCl_(aq). Record.

3. Measure the temperature (to TWO decimal places) of both solutions. Record.

4. Mix the two materials into a coffee cup calorimeter, cap it, stir the contents, and measure the temperature (to TWO decimal places) every 15 seconds for 2 minutes (or more, as needed until temperature stops increasing). Record.

5. Clean up.

Part C:

1. Write the equation for the reaction between solid sodium hydroxide and aqueous hydrochloric acid.

2. Get a coffee cup calorimeter, tare the electronic scale, and weight the calorimeter. Record.