Homework 6/30/13

9) 55 * +20 = 11 grams sugar

55 – 11 = 44 grams water

10)  150,000 ppm

11) A water molecule is polar because it has a negative charge (oxygen) and two positive charges (hydrogen), which attract one another.

12) 

13)

a. oxygen because it is negatively charged

b. hydrogen because it is positively charged

14) Heavy metals are called heavy because their atoms have greater masses than those of essential metallic elements; therefore, are harmful to humans and other organisms.

15) Three symptoms of heavy metal poisoning are numbness, tunnel vision, and brain damage.

16)

a. Humans might have been exposed to lead because while lead was added to gasoline to produces a better burning automobile fuel, the lead entered the atmosphere through automobile exhaust as lead oxide.

b. Humans might have been exposed to mercury because mercury was used to make felt hats; however, hat makers suffered from mercury poisoning  after absorbing this compound through their skin.

17) Hydroxide ions (OH-) are found in many bases.

18) Hydrogen (H) is found in many acids.

19)

a. basic

b. basic

c. acidic

d. chemically neutral

20) 

a. soft drink

b. black coffee

c. milk of magnesia

21) There is a tenfold difference between units on the pH scale; therefore, a solution is 100 times more acidic at 2.0 than 4.0/

22)

Acidic: Fish egg development is impaired and the concentrations of metal ions in natural waters is increased by leaching metal ions from surrounding soil.

Basic: Dissolve organize materials, like skin and scales on fish.

23) A polar molecule is a molecule with regions of partial positive and negative charge resulting from the uneven distribution of electrical charge. An example is water; there are 2 hydrogen molecules and 1 oxygen molecule. A nonpolar molecule is a molecule that has an even distribution of electrical charge with no regions of partial positive and negative charge.

24) Since water and ethanol are both polar substances, I  would choose lamp oil because it is non polar.

25) NaCl is a polar molecule; therefore, it dissolves in water which is also a polar substance. However, oil is non polar; therefore, it does not dissolve well in water.

26) The phrase “like dissolves like,” explains the pattern of solubility behavior. Polar substances dissolve is polar solvents and non polar substances dissolve in non polar solvents.

27) Water is composed of polar molecules while grease is composed of non polar molecules; therefore, the water would not be able to dissolve the oil off the pan. In order for the grease to come off, it would have to be clean the dish with a non polar substance.

33)

a. Non polar materials are likely to be found in these cleaners.

b. These cleaners are non polar and would be able to dissolve the grease off their hands. Water is polar, therefore it would not be able to dissolve the grease.

35) If fluorine has the highest electronegativity than it has the most electrons, and is negative. Thus, hydrogen must have less electrons and has a positive charge.