Question

Calculate the standard enthalpy change (∆H°) for the vaporization of 10 grams of water at 100°C, given that the molar heat of vaporization of water is 40.7 kJ/mol.

Answer 1

To calculate the standard enthalpy change for the vaporization of 10 grams of water, we need to first determine the number of moles of water and then use the molar heat of vaporization to find the enthalpy change.1. Calculate the number of moles of water:The molar mass of water  HO  is approximately 18.015 g/mol  1.008 g/mol for hydrogen and 15.999 g/mol for oxygen .Number of moles = mass / molar massNumber of moles = 10 g / 18.015 g/mol  0.555 moles2. Calculate the standard enthalpy change  H  using the molar heat of vaporization:H = number of moles  molar heat of vaporizationH = 0.555 moles  40.7 kJ/mol  22.59 kJThe standard enthalpy change for the vaporization of 10 grams of water at 100C is approximately 22.59 kJ.