When it comes to physical changes like phase changes, there are two types of heat energy: sensible heat and latent heat. Sensible heat is the heat absorbed/released when you heat the substance but it doesn't change phase. An example would be heating lukewarm water. The substance is liquid all throughout. Latent heat, on the other hand, is the heat absorbed/released when there is a phase change. An example would be boiling water, because it changes liquid to vapor.
Hence, for freezing liquid, you use the latent heat, specifically the heat of fusion. The answer should be
2.5 g * (1 mol/18.02 g) * 6.03 kJ/mol = 0.84 kJ/mol
The answer is not in the choices. You only use Hvap if you boil water.
Answer:
95.3g
Explanation:
Given parameters:
Mass of water = 540g
Percentage by mass of solution = 15%
Unknown:
Mass of sucrose = ?
Solution;
To solve this problem, we must understand that a solution is made up of solute dissolved in a solvent. A solute is the solid dissolved in another. The solvent is the is dissolving medium;
Percentage by mass of solute in solution = 
Mass of solution = mass of water + Mass of sucrose = 540 + M
where M is the mass of sucrose;
therefore;
= 15
Solving for M gives 95.3g
Mass of sucrose is 95.3g
KE = 1/2 * m * v^2
KE = 1/2 * 130 * 23^2
KE = 34385J