Question

The addition of 107.0 g potassium fluoride to 595.0 ml of water (density = 1.00 g/ml) causes the temperature to rise 3.31 °C. What is the ΔHrxn for KF? (Assume the specific heat capacity is 4.18 J/g °C.)

Answer 1

The ΔHrxn for KF is 4347.31 J/mol.

Step-by-step explanation:

To determine the ΔHrxn for KF, we first need to calculate the heat absorbed by the water. The formula for calculating heat (q) is q = m * c * ΔT, where m is the mass of the water, c is the specific heat capacity of water, and ΔT is the change in temperature.

Given that the mass of water is 595.0 g and the change in temperature is 3.31 °C, we can calculate the heat absorbed by the water.

q = (m water) * c * ΔT = (595.0 g) * (4.18 J/g °C) * (3.31 °C) = 8004.14 J

Next, we need to calculate the moles of KF by dividing its mass by its molar mass. The molar mass of KF is 58.1 g/mol, so the moles of KF is:

moles = (mass) / (molar mass) = (107.0 g) / (58.1 g/mol) = 1.842 mol

Finally, we can calculate the ΔHrxn using the formula ΔHrxn = q / moles

ΔHrxn = (8004.14 J) / (1.842 mol) = 4347.31 J/mol