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 joules/gram-K.)

Question

Quizplus · Accepted Answer

First, we need to calculate the mass of the solution using its density:

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

Next, we can use the formula:

ΔH = (mass)(specific heat)(ΔT)

where ΔH is the enthalpy change, ΔT is the change in temperature, and we plug in the values given:

ΔH = (312.5 g)(3.74 J/g-K)(7.80 °C)

ΔH = -9,117.75 J = -9.12 kJ (rounded to two decimal places)

The negative sign indicates that the reaction is exothermic, meaning it releases heat to the surroundings. Therefore, the answer is (D).

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