By law of conservation of energy, the amount of heat lost
by the metal should be equal to the amount of heat gained by water. That is,
the change in energy (expressed in enthalpies) should be equal:
- (ΔH)metal = (ΔH)water
Take note of the negative sign in front of (ΔH)metal, this
means that heat is lost by this metal.
Where ΔH or change in enthalpy is:
ΔH = m Cp (T2 – T1)
So,
- 15 g (Cp) (23 °C – 99 °C) = 75 g (4.18 J/g * °C) (26 °C –
23 °C)
1,140 Cp = 940.5
Cp = 0.825 J/g * °C (ANSWER)
