Question

Calculate the standard enthalpy change for the vaporization of 25 g of liquid nitrogen at its boiling point assuming constant pressure is 1 atm. Given the molar heat of vaporization of nitrogen is 5.56 kJ/mol.

Answer 1

To calculate the standard enthalpy change for the vaporization of 25 g of liquid nitrogen, we first need to determine the number of moles of nitrogen in the sample. The molar mass of nitrogen  N2  is 28.02 g/mol.Number of moles = mass / molar massNumber of moles = 25 g /  28.02 g/mol  = 0.892 molNow, we can use the molar heat of vaporization  Hvap  to calculate the enthalpy change for the vaporization of the sample.H = number of moles  HvapH = 0.892 mol  5.56 kJ/mol = 4.96 kJTherefore, the standard enthalpy change for the vaporization of 25 g of liquid nitrogen at its boiling point is 4.96 kJ.