7 An open cooking pot containing 0.5 liter of water at 208C, 1 bar sits on a stove burner. Once the burner is turned on, the water is gradually heated at a rate of 0.85 kW while pressure remains constant. After a period of time, the water starts boiling and continues to do so until all of the water has evaporated. Determine (a) the time required for the onset of evaporation, in s. (b) the time required for all of the water to evaporate, in s, once evaporation starts.