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

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

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

Now, we can use the formula:

ΔH = m x c x ΔT

where: 
m = mass of the solution (in grams) = 312.5 g 
c = specific heat of the solution = 3.74 J/g*K 
ΔT = change in temperature = 7.80°C

ΔH = 312.5 g x 3.74 J/g*K x 7.80°C = 9152.25 J = 9.15 kJ

Therefore, the enthalpy change of the chemical reaction is -9.15 kJ (since the temperature increase is due to an exothermic reaction). Rounded to two decimal places, the answer is D) -9.12 kJ.

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