Question

How much energy is required to melt 1.5 kg of lead?

Answer 1

`34.53`kJ

Explanation:

The enthalpy of fusion (energy need to change state from solid to liquid) of lead is 4.77 kJ/mol (so it takes 4.77 kJ to melt one mole of lead).
We need to find the number of moles (`n`) of lead in 1.5kg (`m`).

`n=m/M`
From periodic table, M=207.2g/mol
Therefore, `n=(1500g)/(207.2g.mol^-1)`
`n=7.24` moles
Energy `=7.24`moles`*4.77kJ.mol^-1`
Energy `34.53`kJ