Section C Summary: #20-27, 33 & 35.

20.  

a. A soft drink is more acidic because it has a pH of 3, while a tomato’s pH is only about 4.

b. Black coffee is more acidic with a pH of 5, and pure water’s is 7.

Milk of magnesia, while it is a base, is more acidic than household ammonia.

21. The pH scale goes by increments of 10, so a pH solution of 2.0 is 100 times stronger than a solution with a 4.0 pH.

22. Inappropriate pH levels have various effects on aquatic organisms. For example, if water is too basic it can dissolve fish scales. Another example would be if the acidity level got to high, increasing the metal ion concentration, some of which, like aluminum, are toxic to fish. Also, high acidity can affect fish-egg development, causing an inability for fish to reproduce.

23. Polar molecules have an uneven electrical charge distribution, while non-polar molecules have an equal balance of positive and negative charges.

24. I would use lamp oil to dissolve a non-polar molecular substance since it is also non-polar. Water and ethanol are both polar and would be ineffective in dissolving a non-polar solute because “like dissolves like.”

25. Table salt would dissolve in water, but not oil, because both it and water are polar substances, and oil is not.

26. The term, “like dissolves like” means that a non-polar solvent dissolves a non-polar solute, and a polar solvent will dissolve a polar solute. However, this does not mean that non-polar substances are completely insoluble in water. They will dissolve to a certain extent, but not enough to be totally soluble.

27. Water cannot satisfactorily clean greasy dishes because the grease is an oily substance, making it non-polar. Although the water may rinse away the oils, it cannot fully dissolve them. A non=polar cleaning fluid would be more effective for this.

33.  

a. There are likely going to be non-polar materials like carbon dioxide

b. This is more effective because the non-polar materials will dissolve the non-polar oils on mechanics’’ hands, while water will kind of rinse it off.

35.   I would think that hydrogen would have the slightly positive charge. This is because fluorine naturally has more electrons, which would most likely stay attracted to it, leaving hydrogen with almost no electrons.