Question

A mixture of 30.2 g of sand and 87.7 g of water has a temperature of 12.1 °C. What is the mass of water at 85.8° C must be added to raise the final temperature of the mixture to 29.3 C?(cp,w=4.19 J/g· °C and cp,s=2.01 J/g·°C)

Answer 1

Q out = Q in

Q mix = Q water

mcΔt sand + mcΔt water = mcΔt water

30.2 x 2.01 x (29.3-12.1) + 87.7 x 4.19 x (29.3-12.1)=m x 4.19 x (85.8-29.3)

1044.07+6320.36=m x 236.74

m = 31.11 g