Question

What is the final temperature when 100 g of water at 75`"^o`C is mixed with 75 g of water at 80`"^o`C?

Answer 1

These two systems will equilibrate. The system at a higher initial temperature will be exothermic, transferring heat to the contextually endothermic system.

Hence,

`-75g * (4.18J)/(g*°C) * (80°C - T_f) = 100g * (4.18J)/(g*°C) * (75°C - T_f)`

`therefore T_f approx 77°C`

To be sure, this is but a difficult representation of the familiar scenario,

`q = mC_sDeltaT`,

where the heat supplied is merely coming from the exothermic system.