Solutions and Solubility

Question 1

Why does salt dissolve in water but not in a non polar substance? Whereas iodine does not dissolve in water but in does in the non polar substance.

Answer 1

Because water is polar and substance is non polar, their molecules are not attracted to each other. The water molecules of a polar solvent are attracted to other polar molecules and iodine is non polar meaning it won’t dissolve in water, but in a non polar substance.

Question 2

Why is hydrochloric acid a good electricity conductor but concentrated acetic acid is a poor conductor?

Answer 2

Hydrochloric acid dissociates almost entirely into H+ and Cl- which adds a lot of electrolytes to water. Acetic acid, on the other hand, is a weak acid and because it’s concentrated it won’t produce as many electrolytes, and won’t conduct as well

Question 3

How do you prepare 500 ml of a 0.25mol/L solution of sodium hydroxide?

Answer 3

1. add distilled water and stir until the sodium hydroxide has all dissolved
2. Then transfer the solution to a clean volumetric flask
3. Use an eye-dropper to make sure the solution reaches 100ml on the meniscus. Stopper the flask and invert several times.

Question 4

What is the general word equation for any neutralization reaction?

Answer 4

acid + base = salt + water

Question 5

Give an example of a solution consisting of a:

• solid in a solid
• liquid in a liquid
• gas in a gas
• solid in a liquid

Answer 5

Solid in a solid-

Liquid in a liquid- water and chlorine

Gas in a gas- carbon and oxygen (CO2)

Solid in a liquid-sodium in water

Question 6

A crystal of solute is added to an aqueous solution of the same solute. After some time it is noted that the crystal has not changed in mass. Is the solution saturated, unsaturated or super saturated?

Answer 6

Saturated

Question 7

A clear colorless liquid with a density of 1.4 g/ml was boiled. The initial boiling point was 101’C and the successive boiling points were 103’C, 105’C and 107’C. After cooling, the density was found to be 2.0 g/ml. Was the original colorless liquid a pure substance or a solution? Explain.

Answer 7

UNKNOWN ANSWER

Question 8

If a relatively small amount of solute of dissolved in a relatively large amount of solvent, the solution is said to be?

Answer 8

Saturated

Question 9

A homogeneous mixture of two or more substances is know as a(n)?

Answer 9

Solution

Question 10

A saturated solution of potassium nitrate may be made unsaturated by?

Answer 10

Increase the temperature (heating it)

Question 11

If much more solute can be dissolved in a solution without altering the temperature, the solution is said to be?

Answer 11

Super saturated

Question 12

What is the difference between a saturated, a super saturated and an unsaturated solution? How can you tell between them experimentally or through observation?

Answer 12

Saturated- Additional solute cannot dissolve
Unsaturated- Solution that is not saturated yet
Super saturated- Solvent can dissolve more than its the maximum amount

Question 13

Explain 3 factors that have lead to global warming

Answer 13

1. combustion of fossil fuels in cars
2. cutting down forests
3. pollution

Question 14

Definition of:
Solute
Solvent
Solution

Answer 14

Solute- A substance dissolved in another substance, known as a solvent

Solvent- The substance in which the solute is dissolved.

Solution- A homogeneous mixture composed of two or more substances.

Question 15

Relationship between polarity and solubility

Answer 15

“Like dissolves like”. Meaning that polar substances tend to dissolve in polar solvents, and nonpolar substances dissolve in nonpolar solvents.

Question 16

Ions responsible for hard water

Answer 16

Hard water is water containing high amounts of mineral ions. The most common ions found in hard water are the metal cations calcium (Ca2+) and magnesium (Mg2+). These metals are water soluble, meaning they will dissolve in water.

Question 17

Relationship between pH, hydrogen and hydroxide concentrations

Answer 17

The higher the hydrogen ion molar concentration, the lower the pH.
Hydroxide is pOH which should speak for itself

Question 18

Define electrolytes and non-electrolytes

Answer 18

Electrolyte- A chemical compound that ionizes when dissolved to produce an electrically conductive medium.

Non-Electrolyte- A substance that does not exist in an ionic form in aqueous solution.

Question 19

Arrhenius and Bronstead-Lowry definitions of acids and bases

Answer 19

Arrhenius Base Definition: Hydroxide is an OH- dissolved in water.

Bronsted-Lowry Base Definition: Hydroxide attacks and accepts the H+ from hydronium.

Question 20

Strength vs. concentration of an acid or base

Answer 20

Concentration- the amount of acid or base present in a given amount of solution. It contains a large amount of acid or base in a volume. A dilute solution has a small amount of acid or base in a volume.

Acid strength- the degree the acid is ionized in a solution to form hydronium ions. A strong acid completely ionizes in an aqueous solution. A weak acid does not completely ionize.

Base strength- the degree the base is ionized in a solution to form hydroxide ions. (Strong and weak bases react the same as acids.)