How much heat in kJ is required to increase the temperature of an 87.0 g sample of water from 67oC to 136.6oC?
Heat flow in problems like this use q = mcT if a temp change is observed, and q = mH if a phase change is occurring. Here m = mass of substance gaining or losing heat, c = specific heat of substance, T = Temp change and H = Transition Constant for phase change. For this problem, since a Temp change is involved, use q = mcT.
m = 87.0g
c = 4.184 J/gC
T = (136.6 - 67.0)C = 69.6C
q = (87.0)(4.184)(69.6)J = 25335J = 253.35Kj or 253Kj to 3 sig figs
If multiple heat flows are present => Sum of Heat Flows = 0. Substitute given data and solve for unknown.