Unit 2.1 - Materials: Substances and Properties

Different liquids boil at different temperatures. Explain why this is so.

• Boiling point is a property of a substance, so

  different substances will have different boiling

  points.

• This statement is wrong. All substances have the same boiling point.

Which liquid boils at the highest temperature?

• Cooking oil

• Water

• Nail polish remover

• Car engine anti-freeze

Which liquid boils at the lowest temperature?

• Cooking oil

• Water

• Nail polish remover

• Car engine anti-freeze

Answer explanation

Nail polish remover, primarily composed of acetone, boils at around 56°C, which is lower than water (100°C), cooking oil (around 200°C), and car engine anti-freeze (around 100°C). Thus, it has the lowest boiling point.

At what temperature does car engine anti-freeze boil?

• 100°C

• 300°C

• 50°C

• 125°C

Answer explanation

Car engine anti-freeze typically boils at around 125°C due to the presence of additives that raise the boiling point compared to pure water, which boils at 100°C.

Boiling changes a liquid into a gas. Name another process that does this.

• Evaporation

• Condensation

• Melting

• Freezing

Answer explanation

Evaporation is the process where a liquid turns into a gas at temperatures below its boiling point, making it another way to change a liquid into a gas, just like boiling.

Mark the correct temperatures on the thermometer

a

b

c

Boiling point of acetone: 50.5C

Boiling point of water: 100C

Melting point of candle wax: 60C

Which of the following shows a drawing of boiling? A or B?

• A

• B

Answer explanation

Choice B shows boiling, as it depicts bubbles forming and rising in a liquid, which is characteristic of the boiling process. Choice A does not illustrate this phenomenon.

If B shows boiling, what process does the other drawing show?

• Condensation

• Melting

• Evaporation

• Freezing

Answer explanation

If B shows boiling, it indicates a phase change from liquid to gas. The other drawing likely shows evaporation, which is the process of liquid turning into vapor at temperatures below boiling.

Organise the statements into similarities and differences of boiling and evaporation

Groups:

(a) Similarities

,

(b) Differences

• They change a liquid into a gas

• The speed of the particles in these process are very different.

• Evaporation occurs at any temperature

• Boiling occurs at 100C only

• They occur at different temperatures

Predict what you think the temperature will be in: Beaker B

• 100C

• 50C

• 0C

• -50C

Answer explanation

The temperature in Beaker B is predicted to be 100C because it is likely being heated or is in a reaction that generates heat, making this the most plausible option among the choices.