The Dissolving of Solid Sodium Hydroxide in Water
Procedure:
1. Measure out approximately 200 mL of distilled water and pour it into the calorimeter. Stir carefully with a thermometer until a constant temperature is reached. Record the volume of water and the constant initial temperature of the water on your data table. 2. Place a plastic measuring trough on top of the digital balance, and then zero the balance (press the tare button) so that the mass of the trough will be "ignored" and will not be added to the total mass measured by the balance. 3. Measure out approximately three to five scoops of solid sodium hydroxide and record the mass to your data table. 4. Place the solid sodium hydroxide into the water in the…show more content… a. Write the balanced chemical reaction and enthalpy change for Part I (1pt)
b. Write the balanced chemical reaction and enthalpy change for Part II (1pt)
c. Calculate the enthalpy change using Hess's Law. Refer to the lesson for an example of Hess's Law. (2pt) 2. If the accepted enthalpy change value for the dissolving of sodium hydroxide in water is −44.2 kilojoules per mole, determine the percent error of the experimental value that you calculated in Part I. Show your work.
(experimental - actual value) / actual value × 100 % 3. If the accepted heat of reaction for the neutralization of hydrochloric acid with sodium hydroxide is −56.0 kilojoules per mole, determine the percent error of the experimental value that you calculated in Part II. Show your work.
(experimental - actual value) / actual value × 100 % 4. Using the accepted values of the processes you've examined, would your estimation of the enthalpy change for the reaction of solid sodium hydroxide in aqueous hydrochloric acid change from the prediction you made in question one? Explain your answer in complete sentences. 5. Give a detailed explanation, using what you know about bonds and forces of attraction, for the enthalpy changes you observed in parts I and II of this lab. Explain your answer in complete sentences. 6. If the hole for the thermometer in a calorimeter is wider than the diameter of the thermometer, leaving a gap between the lid and the thermometer
