During a laboratory distillation process, a flask is filled with 1.2 kg1.2\text{ kg}1.2 kg of liquid ethanol at an initial temperature of 18∘C18^\circ\text{C}18∘C. An electric immersion heater rated at 1.8 kW1.8\text{ kW}1.8 kW is used to heat the ethanol. The heater is switched on for a duration of 6.5 minutes6.5\text{ minutes}6.5 minutes.
Calculate the total thermal energy supplied by the immersion heater during the 6.5 minutes6.5\text{ minutes}6.5 minutes.
The specific heat capacity of liquid ethanol is 2400 J kg−1 K−12400\text{ J kg}^{-1}\text{ K}^{-1}2400 J kg−1 K−1, and its specific latent heat of vaporisation is 8.5×105 J kg−18.5 \times 10^5\text{ J kg}^{-1}8.5×105 J kg−1. The boiling point of ethanol is 78∘C78^\circ\text{C}78∘C.
Calculate the mass of liquid ethanol remaining in the flask after 6.5 minutes6.5\text{ minutes}6.5 minutes of heating. Assume that all thermal energy from the heater is transferred directly to the ethanol and that no energy is lost to the surroundings or the flask.