Question

Calculate the enthalpy change expected when 50.0g of water vaporizes, if the molar enthalpy of vaporization ofwater is 44.0 kJ/mol.

Answer 1

The formula used here:

Enthalpy change = moles x molar enthalpy of vaporization

We already have 50.0 g of water. We should convert it to moles using the molar mass of water.

*Moles = mass/molar mass

The molar mass of water = 18.0 g/mol => 50.0 g/18.0 g/mol = 2.78 moles

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The molar Enthalpy of vaporization = 44.0 kJ/mol

Now, Enthalpy change = 2.78 moles x 44.0 kJ/mol = 122 kJ

Answer: enthalpy change = 122 kJ