Question

Part A How much heat energy, in kilojoules, is required to convert 56.0 g of ice at −18.0 ∘C to water at 25.0 ∘C ? Express your answer to three significant figures and include the appropriate units.

Answer 1

Sensible heat (CP): heat change due to Temperature difference

Latent heat (LH): Heat involved in changing phases (no change of T)

Then

Q1 = m*Cp ice * (Tf – T1)

Q2 = m*LH ice

Q3 = m*Cp wáter * (Tb – Tf)

Note that Tf = 0°C; Tb = 100°C, LH ice = 334 kJ/kg; LH water = 2264.76 kJ/kg.

Cp ice = 2.01 J/g°C ; Cp water = 4.184 J/g°C; Cp vapor = 2.030 kJ/kg°C

Then

Q1 = 56*2.01 * (0 – -18)

Q2 = 56*334

Q3 = 56*4.184 * (25– 0)

QT = Q1+Q2+Q3 = 2026.08 + 18704+5857.6 = 26587.68 J = 26.58 kJ