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.