A piece of copper metal (specific heat 0.385 J/g∘C) at 85.6 ∘C is placed in 50.0 g of water at 16.2 ∘C. The metal and water come to the same temperature of 23.6 ∘C. What is the mass?

Answer 1

use the formula q = m*c*deltaT

Answer 2

I assume you are asking for the mass of the Cu since you already have the mass of the water.
[mass Cu x specific heat Cu x (Tfinal-Tinitial)] + [mass H2O x specific heat H2o x (Tfinal-Tinitial)] = 0
Substitute the numbers and solve for mass Cu metal.