WAEC 1989 A 117200 65. An electric heater immersed in some water raises the temperature of the water
from 40°C to 100°C in 6 minutes. After another 25 minutes, it is noticed that half the
water has boiled away. Neglecting heat losses to surrounding, calculate the specific latent
heat of vapourization of water.

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8.29 two streams containing pyridine and acetic acid at 25°c are mixed and fed into a heat exchanger. due to the heat-of-mixing effect, it is desired to reduce the temperature after mixing to 25°c using a stream of chilled ethylene glycol as indicated in the diagram. calculate the mass flow rate of ethylene glycol needed. the heat capacity of ethylene glycol at these conditions is approximately 2.8 kj/(kg k), and the enthalpy change of mixing (δmixh) is given below.