A 50 g sample of aluminum at 90 °C is placed into 100 g of water at 20 °C in a perfectly insulated calorimeter. The specific heat capacities are cAl=0.90J g−1∘C−1 and cwater=4.18J g−1∘C−1. What is the approximate final equilibrium temperature of the system?
a) 43∘C
b) 50∘C
c) 27∘C
d) 70∘C