Pamela's+Water+Usage

**Chapter 10: Pamela Yip :D **

Question 15)
 * __Usage__           ||    __Amount__||
 * Toilet/Hand Wash   ||13.3	       ||
 * Morning washing face||3.8           ||
 * Breakfast/Dishes   ||20.3           ||
 * Drink	             ||2              ||
 * Wash Clothes	     ||38             ||
 * Toilet/Hand Wash   ||13.3           ||
 * Shower             ||73             ||
 * Drink	             ||3              ||
 * Dinner/Dishes      ||20.3           ||
 * Wash Face          ||3.8            ||
 * Total Usuage (L)   || 187  (L)      ||
 * Total Usuage (L)   || 187  (L)      ||

Question 17) Glass bottles of drink placed in the freezer compartment of a refrigerator often crack if left there for several hours due the the liquid expanding. When water is becoming solidified, it expands whilst the glass has no effect. This causes the glass to crack because of the pressure from the ice.

Question 20) Water is a good solvent for polar and ionic substances for the following 3 reasons!

a) It has a high dielectric constant

The dielectric constant for water is 80 which is much higher than hexane for example which has a dielectric constant of 2. The force between two ions at a given separation is therefore about 40 times greater in hexane than water. Ionic compounds will therefore dissolve in water more easily than hexane.

b) Solvation of ions by water molecules shields them from ions of opposite charge and reduces their tendency to reform the ionic solid.

c) Water can H-bond with a molecule or groups on a molecule, then the molecule will be soluble. Biomolecules contain many charged and polar groups and amino which can hydrogen bond with water making them soluble.

Question 23)

Working out showed in exercise book