Question

If brass is 35% zinc and 65% copper by mass, calculate the molar heat capacity of brass. ( Specific heat capacity of brass is 0.377 J/g.C)

Answer 1

Atomic mass of zinc (Zn) = 65.38 g/mol

Amount of Zn in brass = 35 %

1 g brass contains = 1 x 35/100 = 0.35 g Zn

Moles of Zn = 0.35/65.38 = 0.005 mol

Atomic mass of copper (Cu) = 63.55 g/mol

Amount of Cu in brass = 65 %

1 g brass contains = 1 x 65/100 = 0.65 g Cu

Moles of Cu = 0.65/63.55 = 0.010 mol

Total moles of Zn and Cu = 0.005 + 0.010 mol = 0.015 mol

Specific heat capacity of brass = 0.377 J/g^-1oC^-1

Therefore molar heat capacity = 0.377/0.015 = 25.1 J/mol^-1oC^-1