Question

(a) How much heat transfer (in kJ) is necessary to raise the temperature of a 0.210 kg piece of ice from -22.0°C to 132°C, including the energy needed for phase changes? (Assume the substance remains at a constant volume throughout each stage of the heating process.) (b) How much time (in s) is required for each stage, assuming a constant 19.0 kJ/s rate of heat transfer? (Enter your answers as a comma-separated list. Enter your times in order from the earliest stage to the final stage of the heating process.) (c) Make a graph of temperature versus time for this process. T("C) 1401 120 100 T(°C) 140 120 100 80 60 60 401 201 -20% - 204 -20% TIL IL ts) _ILLIts) 20 25 30 35 5 35 t(s) 10 15 25 30 1 2 3 4 5 6 7 T(°C) T(°C) 140 1401 120 120- 100 60- 204 04 -A rt(s) -201 25 30 351 5 10 15 20 1 2 TITILIILt(s) 3 4 5 6 7 8 9 10

Answer 1

Solution: - a) DH heat requured te for temproture change from (-22°C to o°c) = mgat - 0.210 X 2.108X(D-(-22) AH, = 9.74 kj DH₂ - heat required for phase change (SL) = meet = (0-120x 3.36x103) ::0H, = 40.32 kj ₂ ► heat required for tempareture Change from ( 0°>1000) = ms, OT = 0.120x 4.186x (100-0"] DH₂ = 50.23 kj Aha heat required for phase change (Lv) mle = 10120 X 2260-) .. AHA = 271.2 14; DHS heat required for temperature Change from 100 to 1320 ASAT = 0.190 X 2.010 x (132-100) 3. AM = 7.72 Kj Total heat pons fer sr + Antona + Motone :. 379.21 KM

b) t = DHI 9.74 19 To- 0.51sec DH2 19 40.32 19 2.12 sec DH3 19 50.23 19 - 2.64 sec. t2 = 962 - 10:32 = 2.12 sec to - moto - 500g 2.64 se to - Studio - 27.32 14.29 ts - HE - 7.72 = 0.41 sec. AH 4 - 271.2 19 - 14.27 see 19 19 0.51, 2012, 2.64, 14.27,0.41 C) 1320 100° 19.95 0.51 2.63 5.27 19.54