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 by 7.80°C? (The specific heat of the solution is 3.74 J/g∙K.)

Question

Quizplus · Accepted Answer

To solve for the enthalpy change of the reaction, we need to use the formula:

q = mCΔT

where:
q = heat absorbed/lost by the solution (in J)
m = mass of the solution (in g)
C = specific heat of the solution (in J/g·K)
ΔT = change in temperature (in K or °C)

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

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

Next, we can plug in the given values:

q = (312.5 g) x (3.74 J/g·K) x (7.80°C) = 9126.75 J or 9.13 kJ

Note: We used the Celsius value for ΔT, which is the same as the Kelvin value in this case.

The heat absorbed by the solution is equal to the heat lost by the reaction. Therefore, the enthalpy change of the reaction is -9.13 kJ, which is closest to choice D (-9.12 kJ).

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