A 275 g sample of a substance suspected of being pure gold i

A 2.75 g sample of a substance suspected of being pure gold is warmed to 72.9 C and submerged into 15.9 g of water initially at 24.3 C. The final temperature of the mixture is 26.3 C. What is the specific heat capacity of the unknown substance? Express your answer using two significant figures

Could the substance be pure gold?

Solution

From calorimetry principle,

heat lost by metal = heat gained by water

(m x S x dT) _metal = (m x S x dT)_water

2.75 g x S x ( 72.9 - 26.3 ) = 15.9 g x 4.184 J/g.C ( 26.3 - 24.3 ) C

=> S = specific heat capacity of metal = 1.04 J/g.C

=> S = specific heat capacity of metal = 1.0 J/g.C ( rounded to 2 sig.fig )

SPecific heat capacity of gold is 0.129 J/g.C at 25 C,

Therefore, the substance could not be pure gold