Question

Calculate the standard enthalpy change for the dissolution of 10 g of NaOH in 100 mL of water at 25°C if the molar enthalpy of dissolution is -44.5 kJ/mol.

Answer 1

First, we need to determine the number of moles of NaOH in 10 g. The molar mass of NaOH is:NaOH = 22.99 g/mol  Na  + 15.999 g/mol  O  + 1.007 g/mol  H  = 39.996 g/molNow, we can calculate the number of moles of NaOH:moles of NaOH = mass / molar massmoles of NaOH = 10 g / 39.996 g/mol = 0.2501 molNext, we can calculate the standard enthalpy change for the dissolution of 0.2501 mol of NaOH using the given molar enthalpy of dissolution:H = moles  molar enthalpy of dissolutionH = 0.2501 mol   -44.5 kJ/mol  = -11.129 kJThe standard enthalpy change for the dissolution of 10 g of NaOH in 100 mL of water at 25C is -11.129 kJ.