Final answer:
The enthalpy change when 69.2 g of sulfuric acid is cooled from 34.0°C to 11.0°C is -2.2555 kJ, which is calculated using the molar heat capacity of sulfuric acid and the temperature change.
Step-by-step explanation:
The enthalpy change when 69.2g of sulfuric acid is cooled from 34.0°C to 11.0°C can be calculated using the equation ΔH = m · c · ΔT, where ΔH is the change in enthalpy, m is the mass of the substance, c is the specific heat capacity, and ΔT is the change in temperature.
First, we need to calculate the number of moles of sulfuric acid (H2SO4) present in 69.2 g. The molar mass of H2SO4 is approximately Therefore: 98.079 g/mol.
Moles of H2SO4 = mass (g) / molar mass (g/mol) = 69.2 g / 98.079 g/mol ≈ 0.706 mol
Next, we use the molar heat capacity of sulfuric acid , which is 138.9 J/k -mol, and multiply by the number of moles and the temperature change ΔT (34.0°C - 11.0°C = 23°C):
ΔH = 0.706 mol · 138.9 J/K·mol · 23 K = 2255.5 J
Lastly, we convert joules to kilojoules by dividing by 1000:
ΔH = 2255.5 J / 1000 = 2.2555 KJ
The enthalpy change is negative since the sulfuric acid is cooling down and releasing heat to the surroundings:
ΔH = -2.2555 kJ