a 31.5 g wafer of pure gold initially at 69.9 ∘c is submerged into 63.3 g of water at 26.9 ∘c in an insulated container. the specific heat capacity for gold is 0.128 j/(g⋅∘c) and the specific heat capacity for water is 4.18 j/(g⋅∘c). what is the final temperature of both substances at thermal equilibrium?