Module 4

Question 0

1b. define: polar molecule

Answer 0

a molecule that has slight positive and negative charges due to an imbalance in the way electrons are shared

Question 1

1a. define: electrolysis

Answer 1

the use of electricity to break a molecule down into smaller units

Question 2

1c. define: solvent

Answer 2

a liquid substance capable of dissolving other substances

Question 3

1d. define: solute

Answer 3

a substance that is dissolved in a solvent

Question 4

1e. define: cohesion

Answer 4

the phenomenon that occurs when individual molecules are so strongly attracted to each other that they tend to stay together, even when exposed to tension.

Question 5

1f. define: hard water

Answer 5

water that has certain dissolved ions in it- predominately calcium and magnesium ions

Question 6

2. Suppose you did an electrolysis experiment like Experiment 4.1 on hydrogen peroxide, which has a chemical formula of h202. if it worked out properly, which of the following results would you expect:
   (a) same as with water
   (b) equal amounts of hydrogen and oxygeen
   or
   (c) twice as much oxygen as hydrogen

Answer 6

option (b); equal amounts of oxygen and hydrogen

Question 7

3. Suppose you did an electrolysis experiment like experiment 4.1 with a test tube that had a crack in it. Gas could slowly leak out that crack, but not nearly as quickly as it was being made in the experiment. Suppose further that the crack was in the test tube that held the oxygen gas. Which chemiclal formula might result from such a botched experiment: HO or H4O?

Answer 7

The chemical formula HO would be the more likely erroneous result.

Question 8

4. Epsom salts, has the chemical formula MgSO4. If Mg is the symbol for magnesium, S stands for sulfur, and O represents oxygen, how many of each atom exists in a molecule of Epsom salts?

Answer 8

one magnesium atom and one sulfur atom, four oxygen atoms

Question 9

5. Calcium carbonate is an ionic substance commonly called “chalk.” If this molecule has one calcium atom (Ca), one carbon atom (C), and three oxygen atoms (O), what is its chemical formula?

Answer 9

CaCO3

Question 10

6. One of the most common household cleaners is ammonia, which has a chemical formula of NH3. How many atoms are in a molecule of ammonia?

Answer 10

four

Question 11

7. A certain molecule is composed of atoms that all pull on electrons with the same strength. Will this molecule be polar?

Answer 11

no, the molecule will not be polar

Question 12

8. Baking soda dissolves in water. Will it dissolve in vegetable oil, which is a nonpolar substance?

Answer 12

baking soda will not dissolve in vegetable oil

Question 13

9. Carbon tetrachloride will not dissolve in water. Is it most likely made of ionic molecules, polar molecules or nonpolar molecules?

Answer 13

carbon tetrachloride is probably made of nonpolar molecules

Question 14

10. Suppose you were able to count the molecules in a substance. Which would have more molecules, 1 liter of liquid water or 1 liter of ice?

Answer 14

the liquid would have more molecules

Question 15

11. If the substance in question #10 were virtually any other substance, what would the answer be?

Answer 15

For nearly any other substance, the answer would be that solid would have more molecules.

Question 16

12. What is responsible for water being a liquid at room temperature as well as for water’s cohesion?

Answer 16

hydrogen bonding

Question 17

13. What causes surface tension?

Answer 17

cohesion

Question 18

14. Why is water harder in certian regions of the world than in others?

Answer 18

there is a higher amount of metal-containing substances in some regions than others