Question

What is the amount of energy liberated in joules when 85 g of water cools from 45 C to 25 C.?

Answer 1

Given,

`DeltaT = -20°C`

`m = 85"g"`

`C_s = (4.18"J")/("g"*°"C")`

Now, recall,

`q = mC_sDeltaT`

The water is releasing heat, so this is an exothermic process, thus `q<0`.

Hence,

`q = mC_sDeltaT approx (-7.11*10^3"J")/"mol"`

of kinetic energy are released from the system in the form of heat.