PS Module 4

Question 1

Using electricity to break a molecule down into smaller units.

Answer 1

Electrolysis

Question 2

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

Answer 2

Polar molecule

Question 3

A liquid substance capable of dissolving other substances.

Answer 3

Solvent

Question 4

A substance that is dissolved in a solvent.

Answer 4

Solute

Question 5

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.

Answer 5

Cohesion

Question 6

Water that has certain dissolved ions in it, predominantly calcium and magnesium ions.

Answer 6

hard water

Question 7

What if you did Experiment 4.1 using hydrogen peroxide (H2O2) instead of water (H2O)? How would the results be different?

Answer 7

The result would be equal amounts of oxygen & hydrogen.

Question 8

What if you did Experiment 4.1 with a crack in the Hydrogen test tube? Which chemical formula might result from this botched experiment, HO or H4O?

Answer 8

HO

Question 9

How many of each atom are in a molecule of epsom salts (MgSO4) where the atoms are Mg(magnesium), S(sulfur), O(oxygen)?

Answer 9

Mg = 1, S = 1, O = 4

Question 10

Calcium carbonate, or chalk, molecules have one calcium atom (Ca), one carbon atom (C), and three oxygen atoms (O). What is its chemical formula?

Answer 10

CaCO3

Question 11

How many atoms are in one molecule of ammonia (NH3)?

Answer 11

1 N + 3 H = 4 molecules

Question 12

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

Answer 12

No, non-polar because none will be able to get more than its fair share.

Question 13

If baking soda dissolves in water will it dissolve in vegetable oil which is a nonpolar substance?

Answer 13

No, because it is either ionic or polar since it dissolved in water. Only nonpolar substances will dissolve in other nonpolar substances.

Question 14

If a substance will not dissolve in water, it is most likely?

Answer 14

non-polar

Question 15

Which has more molecules, 1 liter of liquid water or 1 liter of ice?

Answer 15

The liquid water because the molecules in solid water are farther apart so for the same volume there will be more molecules in the liquid.

Question 16

In comparing 1 liter of liquid water to 1 liter of ice, if the substance were virtually any other substance, which would have more molecules?

Answer 16

The solid state would have more molecules because they are closer together in the solid state giving more molecules.

Question 17

What is responsible for water being a liquid at room temperature and also water cohesion?

Answer 17

hydrogen bonding

Question 18

What causes surface tension?

Answer 18

cohesion

Question 19

Hard water is the result of what? Why is it harder in some regions of the world?

Answer 19

calcium-containing compounds. It’s harder because there is a higher amount of calcium-containing substances.

Question 20

Is water a molecule or an atom?

Answer 20

molecule

Question 21

What is the chemical formula for water?

Answer 21

H2O

Question 22

Why are water molecules polar?

Answer 22

Water molecules are polar because both Oxygen atoms and Hydrogen atoms are fighting over the electrons they are supposed to be sharing. Oxygen can pull on those electrons harder, getting more than its share of electrons, making it slightly negative. Since the hydrogen atoms get less than their fair share of electrons, they end up slightly positive.

Question 23

Oxygen can pull on electrons because it gets more than its fair share of electrons, making it slightly what?

Answer 23

Oxygen atoms end up slightly negative because it gets more than its fair share of electrons.

Question 24

Since hydrogen atoms get less than their fair share of electrons, they end up slightly what?

Answer 24

Hydrogen atoms end up slightly positive since they get less than their fair share of atoms.

Question 25

Why is water harder in some regions of the world than in others?

Answer 25

Water is harder in some regions of the world because there is a higher amount of metal-containing substances in some regions than others. The dissolved metal ions are what causes the hard water.