Question

What is the enthalpy change when 50.0 grams of ammonium chloride (NH4Cl) is dissolved in 250.0 mL of water at 25°C? The molar enthalpy of dissolution of NH4Cl is -14.8 kJ/mol.

Answer 1

To calculate the enthalpy change, we first need to determine the number of moles of NH4Cl in 50.0 grams. The molar mass of NH4Cl is:Molar mass of NH4Cl = 14.01  N  + 4 * 1.01  H  + 35.45  Cl  = 53.49 g/molNow, we can find the number of moles of NH4Cl:moles of NH4Cl = mass / molar mass = 50.0 g / 53.49 g/mol = 0.934 molNext, we can use the molar enthalpy of dissolution to find the enthalpy change:Enthalpy change = moles * molar enthalpy of dissolution = 0.934 mol *  -14.8 kJ/mol  = -13.82 kJTherefore, the enthalpy change when 50.0 grams of ammonium chloride is dissolved in 250.0 mL of water at 25C is -13.82 kJ.