Question

Copper has a Hfus = 13.0 kJ/mol. What mass of copper releases 112.4 kJ of heat as it freezes? 9.42 g 6.75 g 549 g 1590 g

Answer 1

Answer is: mass of copper is 549 g.

Hfus(Cu) = 13.0 kJ/mol; the heat of fusion of copper..

Q = 112.4 kJ; heat released.

Q = n(Cu) · Hfus(Cu).

n(Cu) = Q ÷ Hfus(Cu).

n(Cu) = 112.4 kJ ÷ 13.0 kJ/mol.

n(Cu) = 8.65 mol; amount of copper.

m(Cu) = m(Cu) · M(Cu).

m(Cu) = 8.65 mol · 63.546 g/mol.

m(Cu) = 549.428 g; mass of copper.

Answer 2

Heat of fusion is the heat absorbed by a unit mass of a given solid at its melting point that completely converts the solid to a liquid at the same temperature. We use this concept to calculate the mass of copper. We do as follows:

H = m(Hfus)
112.4 = m (13.0) ( 1 mol / 63.55 g )
m = 549.4631 g -------> OPTION 3