The main reason that distillation is a costly method for purifying water is the high energy required to heat and vaporize water.
(a) Using the density, specific heat and heat of vaporization of water from Appendix B, calculate the amount of energy required to vaporize 1.00 gal of water beginning with water at 20 °C.
(b) If the energy is provided by electricity costing $0.085 / kWh, calculate its cost.
(c) If distilled water sells in a grocery store for $1.26 per gal, what percentage of the sales price is represented by the cost of the energy?