5.04 × 10^-3 mole of a compound is added to 41.0 g of water in a styrofoam cup and stirred until it dissolves.The temperature of the solution changes from 23.460 °C to 23.420 °C.What is the heat of solution of the compound expressed in kJ/mol? Assume the specific heat of the solution is 4.18 J/g °C.

Question

Quizplus · Accepted Answer

First, calculate the amount of heat absorbed by the water using the equation: 
q = m * c * ΔT 
where q is the amount of heat absorbed, m is the mass of water, c is the specific heat of the solution, and ΔT is the change in temperature. 
Substituting the given values, we get: 
q = (41.0 g) * (4.18 J/g °C) * (-0.04 °C) = -6.83 J 
Note that the temperature decreased, so the heat absorbed is negative. 
Next, calculate the number of moles of the compound using the given amount: 
n = 5.04 × 10^-3 mol 
Finally, calculate the heat of solution, which is the amount of heat absorbed per mole of compound: 
ΔHsoln = q / n = (-6.83 J) / (5.04 × 10^-3 mol) = -1356.55 J/mol = -1.4 kJ/mol 
Note that the answer is negative because the solution is exothermic, meaning that heat is released. Therefore, the correct answer is (C).

504 × 10-3 Mole of a Compound Is Added to 41.0

504 × 10^-3 Mole of a Compound Is Added to 41.0