Question

The molar heat of fusion for Gold is 12.5 kJ/mol. The specific heat capacity of gold is 0.129 J/g oC.

Calculate the amount of energy required to melt 70.0 g of solid Gold and then heat the liquid to 1213 oC? The melting point of gold is 1063 oC.

Answer 1

Step-by-step explanation:

The heat of fusion given has units of kJ / MOL

so we need to find the number of moles in 70 . 0 g

using periodic table, mole wt for AU =196.97 g/mol

then 70 g is 70 g / 196.97 g/mol = .355 mole

Now to MELT the gold .355 mole * 12.5 kJ/mol = 4.44 kJ ( = 4440 J)

Then to HEAT the liquid to 1213 degrees C from the melting point :

70 g * (1213 - 1063) C * .129 J / (g C) = 1355 J

Then add together 4.44kJ + 1355 J = 4440 J + 1355 J = 5795 J