What is the enthalpy change (in kJ)of a chemical reaction that raises the temperature of 250.0 mL of solution having a density of 1.25 g mL^-1 by 10.2 °C? (The specific heat of the solution is 3.733 J g^-1 K^-1.)

Question

Quizplus · Accepted Answer

First, we need to calculate the mass of the solution:

mass = volume x density = 250.0 mL x 1.25 g/mL = 312.5 g

Next, we can use the formula:

q = m x c x ΔT

q = enthalpy change
m = mass of the solution
c = specific heat of the solution
ΔT = temperature change = 10.2 °C

Plugging in the values, we get:

q = (312.5 g) x (3.733 J/g°C) x (10.2°C)
q = 12,443.44 J or 12.44 kJ (rounded to two decimal places)

The enthalpy change is negative because energy is being released as heat. Therefore, the answer is:

Answer: D (−11.9 kJ)

What Is the Enthalpy Change (In KJ)of a Chemical Reaction