5A2 Solubility and Dissolving Factors

Question 1

Define:

dissolution

Answer 1

It is the process where a solute dissolves in a solvent to form a homogeneous mixture (solution).

Dissolution involves the breakdown of solute particles into ions or molecules, evenly distributed in solvent.

Question 2

List two examples of covalent compounds dissolving in water.

Answer 2

1. Ammonia
2. Chlorine gas

Covalent compounds disintegrate into their components when added to water.

Question 3

What is an example of an ionic compound dissolving in water?

Answer 3

Sodium chloride

(salt)

Ionic compounds break down into negative and positive ions in water.

Question 4

Which solute dissolves in water without breaking covalent bonds?

Answer 4

Table sugar

(C₁₂H₂₂O₁₁)

Water interrupts intermolecular forces but not the covalent bonds in sugar.

Question 5

Define:

rate of solution

Answer 5

It is the speed at which a solute dissolves in a solvent.

Factors like temperature, agitation, and solute particle size influence the rate of solution.

Question 6

What factors affect the rate of dissolution?

Answer 6

• Polarity
• Surface area
• Temperature
• Pressure

These factors influence how quickly a solute dissolves in a solvent.

Question 7

What is the effect of polarity on dissolution?

Answer 7

Polar solvents dissolve polar solutes, and non-polar solvents dissolve non-polar solutes

Like dissolves like.

Question 8

Define:

miscible liquids

Answer 8

Liquids that dissolve completely in each other to form a homogeneous mixture.

Example: Ethanol and water.

Question 9

True or False:

Oil and water are miscible.

Answer 9

False

Oil and water are immiscible because they have different polarities. Hence the saying, “oil and water don’t mix”!

Question 10

How does temperature affect the rate of dissolution?

Answer 10

Higher temperature increases kinetic energy, leading to more frequent and stronger collisions with solute molecules.

Sugar dissolves more quickly in hot tea than in cold tea.

Question 11

Fill in the blank:

Granulated sugar dissolves faster than a sugar cube due to its larger _______ _____.

Answer 11

surface area

Larger surface area increases the frequency of collisions with solvent molecules.

Question 12

Define:

solubility

Answer 12

The maximum amount of solute that can dissolve in a solvent at a specific temperature to form a saturated solution.

It determines how much solute a solvent can hold before saturation occurs.

Question 13

Define:

solubility limit

Answer 13

It is the maximum amount of solute that can be dissolved in a given amount of solvent at a specific temperature.

Any additional solute will not dissolve beyond this limit.

Question 14

Which factors can affect solubility?

Answer 14

• Temperature
• Pressure
• pH
• Stirring/agitation
• Particle size

These factors influence how easily a solute dissolves in a solvent.

Question 15

Fill in the blank:

The solubility of a substance is expressed in _______ per 100 grams of solvent.

Answer 15

grams of solute

Question 16

What is the solubility of NaCl as temperature increases?

Answer 16

It remains fairly constant as temperature increases.

Unlike many other solutes, the solubility of NaCl does not significantly change with temperature.

Question 17

True or False:

Gases dissolve better in liquids at higher temperatures.

Answer 17

False

For gases, solubility decreases with an increase in temperature due to higher kinetic energy causing gas molecules to escape.

Question 18

What happens to a saturated solution if its temperature increases?

Answer 18

It becomes unsaturated.

Increasing the temperature increases the solubility of most solutes, allowing more solute to dissolve.

Question 19

True or False:

Solubility of liquids increases with temperature.

Answer 19

True

Heating increases molecular motion, enabling solutes to dissolve more readily in liquid solvents.

Higher temperatures also weaken intermolecular forces in the solute.

Question 20

How does solute particle size affect solubility?

Answer 20

Smaller particles dissolve faster due to their larger surface area in contact with the solvent.

Larger surface areas provide more opportunity for solvent interactions.

Question 21

How does stirring/agitation affect solubility?

Answer 21

It increases the rate of solubility by bringing more solute particles into contact with the solvent.

It does not change the solubility limit but speeds up the dissolving process.

Question 22

What is a key factor affecting the solubility of gases in solutions?

Answer 22

Pressure

Increasing pressure can increase the solubility of gases in solvents.

Example: Carbon dioxide in carbonated beverages under pressure.

Question 23

Which law relates pressure to solubility of gases?

Answer 23

Henry’s Law

It dictates that the solubility of a gas is directly proportional to its partial pressure.

Question 24

Why does nitrogen dissolve in a scuba diver’s blood?

Answer 24

High pressure under water increases nitrogen solubility in the bloodstream.

Sudden pressure changes can cause nitrogen to diffuse rapidly, leading to decompression sickness.

Question 25

How does the polarity of water **contribute to salt dissolution**?

Answer 25

Water’s polar molecules **attract the positive and negative ions in salt**, separating them. ## Footnote The oxygen in water aligns with Na⁺, while hydrogen aligns with Cl⁻.

Question 26

What happens to carbon dioxide in an **open carbonated beverage**?

Answer 26

**It escapes** as pressure decreases, forming bubbles and making the drink go flat. ## Footnote Pressure maintains CO₂ solubility; reduced pressure leads to gas release.

Question 27

# True or False: The solubility limit can be changed by **increasing the solvent volume**.

Answer 27

False ## Footnote The solubility limit at a given temperature is fixed for each solute-solvent combination.

Question 28

What is a **solubility curve**?

Answer 28

A graph showing the relationship between solute and solvent **at different temperatures**. ## Footnote It indicates the maximum solubility limit for each temperature.

Question 29

What does a **downward sloping** solubility curve indicate?

Answer 29

That **solubility decreases** as temperature increases. ## Footnote This is an exception, as most solubility curves slope upward.

Question 30

What is the customary **unit for temperature** on a solubility curve?

Answer 30

Degrees Celsius | (°C) ## Footnote Temperature is always measured in Celsius on a solubility curve.

Question 31

How can you **read a solubility curve**?

Answer 31

* Find the temperature on the X-axis. * Follow it up to the curve to determine the solubility. ## Footnote Alternatively, you can find the solute amount on the Y-axis and determine the corresponding temperature.

Question 32

What is one **industrial application** of solubility curves?

Answer 32

Creating **accurate metal alloys** by determining the solubility of metals at specific temperatures. ## Footnote Solubility graphs help predict the behavior of solutes in various solvents.

Question 33

# True or False: Solubility curves can help determine **which solute will crystallize first**.

Answer 33

True ## Footnote By comparing solubility at different temperatures, you can predict which solute will crystallize first.