Question

The enthalpy of fusion for Hg is 2.29 kJ/mol. What is the energy change when 78.0 g of Hg melts at −38.8°C?

Answer 1

The enthalpy of fusion for Hg is 2.29 kJ/mol. 0.89 kJ is the energy change when 78.0 g of Hg melts at −38.8°C.

What is Enthalpy of Fusion ?

The amount of energy needed to change 1 mole of substance under state change at constant temperature and pressure is called enthalpy of fusion. It is also known as Latent heat of fusion. Unit of enthalpy of fusion is kJ/mol.

How to find the change in energy ?

To find the change in energy use this expression:

q = n ΔH

where

q = Energy change

n = number of moles

ΔH = Molar enthalpy

Number of moles (n) = $\frac{\text{Given mass}}{\text{Molar mass}}$

                                  = $\frac{78.0\ g}{200\ \text{g/mol}}$

                                  = 0.39 mol

Now put the values in above formula we get

q = n ΔH

  = 0.39 mol × 2.29 kJ/mol

  = 0.89 kJ

Thus from the above conclusion we can say that The enthalpy of fusion for Hg is 2.29 kJ/mol. 0.89 kJ is the energy change when 78.0 g of Hg melts at −38.8°C.

Learn more about the Latent heat of fusion here: brainly.com/question/87248

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