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# Enthalpy question? watch

1. A large kettle operates at 1000 W and holds 5400 g of water when full. The temperature of tap water in spring is 10°C. Assume the water to be pure H2O with the following properties:

molar mass = 18 g mol-1;
CP = 4.2 J mol-1 K-1;
ΔvapH = 41 kJ mol-1 (at 100°C).

(i) How long would the kettle take to boil if filled with tap water? [6 marks]

ΔT = (273+100) - (10 +273) = 90
ΔH = q = CPΔT
therefore, 4.2 J mol-1K-1 x 90K = 378 J mol-1 = q

do we use this equation by anychance:
S (final) = S(initial) + CP ln (T/Ti)

Thank you!

nevermind! I think I've got it!

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