Solubility

Question 1

What is a mixture?

Answer 1

A combination of two or more substances that are not chemically bonded.

Question 2

What is a homogeneous mixture?

Answer 2

A mixture that looks the same throughout (e.g., salt water).

Question 3

What is a heterogeneous mixture?

Answer 3

A mixture where you can see the different parts (e.g., salad).

Question 4

What is a solution?

Answer 4

A homogeneous mixture where one substance is dissolved in another.

Question 5

What is the solute?

Answer 5

The substance that gets dissolved.

Question 6

What is the solvent?

Answer 6

The substance that does the dissolving.

Question 7

What does ‘aqueous’ mean?

Answer 7

A solution where the solvent is water.

Question 8

What does soluble mean?

Answer 8

Able to dissolve in a solvent.

Question 9

What does insoluble mean?

Answer 9

Unable to dissolve in a solvent.

Question 10

What is miscible?

Answer 10

Two liquids that mix completely (e.g., water and ethanol).

Question 11

What is immiscible?

Answer 11

Two liquids that do not mix (e.g., oil and water).

Question 12

How does temperature affect solid solubility?

Answer 12

Higher temperature increases solubility.

Question 13

How does temperature affect gas solubility?

Answer 13

Higher temperature decreases solubility.

Question 14

How does pressure affect gas solubility?

Answer 14

Higher pressure increases gas solubility.

Question 15

Does pressure affect solid or liquid solubility?

Answer 15

Not significantly.

Question 16

What is an electrolyte?

Answer 16

A substance that conducts electricity when dissolved in water (because it forms ions).

Question 17

What is a nonelectrolyte?

Answer 17

A substance that does not conduct electricity in water.

Question 18

What are strong electrolytes?

Answer 18

Substances that completely dissociate into ions (e.g., NaCl, HCl).

Question 19

What are weak electrolytes?

Answer 19

Substances that partially dissociate into ions (e.g., CH₃COOH).

Question 20

What does ‘like dissolves like’ mean?

Answer 20

Polar substances dissolve polar substances; non-polar dissolves non-polar.

Question 21

Can polar substances only dissolve polar ones?

Answer 21

Usually yes, but not always — some substances have both polar and non-polar parts.

Question 22

What compounds are broken into ions in a total ionic equation?

Answer 22

Soluble ionic compounds, strong acids, and strong bases.

Question 23

What compounds stay together in total ionic equations?

Answer 23

Solids, liquids (like H₂O or H₂O₂), gases, weak acids/bases, and molecular compounds.

Question 24

What is a spectator ion?

Answer 24

An ion that appears on both sides of the equation and doesn’t change.

Question 25

What is a net ionic equation?

Answer 25

The total ionic equation with spectator ions removed.

Question 26

What is dynamic equilibrium?

Answer 26

When the forward and reverse reactions happen at the same rate in a closed system.

Question 27

Does dynamic equilibrium mean the reaction stops?

Answer 27

No, reactions continue but there's no net change in concentrations.

Question 28

Do concentrations have to be equal at equilibrium?

Answer 28

No — just constant.

Question 29

What is an Endothermic Process?

Answer 29

A process that absorbs energy from the surroundings. In dissolving, it feels cold because energy is needed to break bonds. ## Footnote Example: KCl dissolving in water.

Question 30

What is an Exothermic Process?

Answer 30

A process that releases energy into the surroundings. In dissolving, it feels warm because more energy is released when new bonds form. ## Footnote Example: NaOH dissolving in water.

Question 31

What does it mean if the temperature increases during dissolving?

Answer 31

This means the process is exothermic — more energy was released than absorbed.

Question 32

What does it mean if the temperature decreases during dissolving?

Answer 32

This means the process is endothermic — more energy was absorbed than released.

Question 33

What is Bond Breaking in Dissolving?

Answer 33

Always requires energy (endothermic). This includes separating solute particles and solvent particles.

Question 34

What is Bond Forming in Dissolving?

Answer 34

Releases energy (exothermic). Happens when solute particles are surrounded by solvent molecules (hydration).