#20-27, 33, 35

20.
a. A soft drink is more acidic than a tomato.
b. Black coffee is more acidic than water.
c. Milk of magnesia is more acidic than household ammonia.

21. It is 20 times more acidic.

22. If the pH of the water that the fish lives in is acidic, it can impair the ability for the fish to reproduce. If the pH is basic, the water can dissolve the skin and the scales of the fish. It is important the the pH remains from 5.0-9.0.

23. Water molecules are polar and water is a polar solvent. Polar solvents such as water dissolve polar substances. Polar molecules have an uneven distribution of electrical charge and nonpolar molecules do not have a separation of charge. Nonpolar molecules do not dissolve very well in polar solvents, instead, they dissolve in nonpolar solvents.

24. I would not select water or ethanol because they are both polar and a nonpolar solvent would be needed to dissolve a nonpolar molecular substance. I would choose lamp oil because it is nonpolar.

25. NaCl dissolves in water because NaCl is a polar molecular compound and water is a polar solvent. It would not dissolve in cooking oil because cooking oil is nonpolar.

26. "like dissolves like" refers to the idea that polar solvents dissolve polar molecular substances and nonpolar solvents dissolve nonpolar molecular substances. It is the matching pattern of solubility.

27. You cannot thoroughly clean greasy dishes with plain water because the polar water can not dissolve the nonpolar grease and oil. In order to effectively clean greasy dishes, one would need to use a nonpolar or basic substance.

33.
a. Nonpolar moles are likely to be found in waterless hand cleaner.
b. Since waterless hand cleaners are used specifically to get the grime off of hands, they are made with nonpolar molecules instead of polar molecules. Thus, being more effective for cleaning the grease off of the mechanic's hands. The polar molecules in water are obviously not going to clean hands with nonpolar substances as well as just simply using nonpolar substances to clean their hands.

35. I would expect hydrogen to have a partial positive charge because if there is a polar bond, there must be a positive atom in the molecule in order for their to be attraction between fluorine and hydrogen. Also, from previous learning, I know that hydrogen is a common positive ion.