Find the false statement(s) about the thermochemistry experiment in which nitric acid is reacted with sodium hydroxide, and the enthalpy of the reaction is measured using an ice calorimeter.
i. Regardless of which strong acid and strong base are used for the neutralization reaction, the reaction occurring is always H3O+ + OH- --> 2H2O
ii. The ice calorimeter is perfectly thermally insulated.
iii. Equal masses of ice and water have the same volume at 0 deg Celsius.
iv. Molar enthalpy of fusion is the enthalpy input required to melt one mole of the solid substance.
v. The reaction in the ice calorimeter was carried out at constant pressure.
a. ) i
b. ) ii, iv
c. ) ii, iii, v
d. ) ii, iii
e. ) iii, v
this question might be based on a lab that we did. the ice calorimeter wasn't insulated because the top was open and it was in a regular beaker. and im pretty sure we didn't do anything to alter the pressure (doesn't pressure only affect gases anyways?).
so my guess would be d)ii, iii
I think you are correct.
To find the false statements about the thermochemistry experiment described, let's go through each statement and evaluate their accuracy:
i. Regardless of which strong acid and strong base are used for the neutralization reaction, the reaction occurring is always H3O+ + OH- --> 2H2O
This statement is true. In a neutralization reaction between a strong acid and a strong base, water is always one of the products. The specific ions involved may vary, but the overall reaction is the same.
ii. The ice calorimeter is perfectly thermally insulated.
This statement is false. As you mentioned, the ice calorimeter used in the experiment was not perfectly thermally insulated because the top was open and it was in a regular beaker. Insulation is necessary to minimize heat exchange with the surroundings, but in this case, the calorimeter was not properly insulated.
iii. Equal masses of ice and water have the same volume at 0 degrees Celsius.
This statement is false. Equal masses of ice and water do not have the same volume at 0 degrees Celsius. Ice is less dense than water, so the volume of ice will be greater than the volume of the same mass of water at this temperature.
iv. Molar enthalpy of fusion is the enthalpy input required to melt one mole of the solid substance.
This statement is true. The molar enthalpy of fusion is indeed the enthalpy input required to melt one mole of a solid substance. It represents the amount of heat energy needed to convert a solid into a liquid at constant temperature and pressure.
v. The reaction in the ice calorimeter was carried out at constant pressure.
This statement is true. In the context of the ice calorimeter experiment, the reaction is carried out at constant pressure. This is usually assumed in experiments conducted in open vessels where the pressure is not actively controlled or manipulated.
Based on the evaluation of each statement, it is clear that statement "iii. Equal masses of ice and water have the same volume at 0 degrees Celsius" is false. Therefore, the correct answer is:
c) ii, iii, v
Based on the information provided, the false statement about the thermochemistry experiment is:
e. ) iii, v
Statement iii is false because equal masses of ice and water do not have the same volume at 0 degrees Celsius. The density of ice is lower than that of water, so equal masses of ice will occupy more volume than water.
Statement v is also false because the ice calorimeter is an example of a constant volume calorimeter, not constant pressure.