High School Chemistry : Help with Properties of Liquids

Study concepts, example questions & explanations for High School Chemistry

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Example Questions

Example Question #5 : Solids And Liquids

Which phase of matter has a definite volume, but no definite shape?

Possible Answers:

Solid

All phases have these qualities

Liquid

Gas

Correct answer:

Liquid

Explanation:

Liquids have a few similar properties to solids. They are not easily compressible and they have a definite constant volume. Unlike solids, however, liquids do not have a definite shape and conform to the structure that contains them. Solids maintain a constant shape.

Gases have no definite shape or volume.

Example Question #6 : Solids And Liquids

What is the freezing point of three moles of HCl dissolved into 1kg of water?

Possible Answers:

Correct answer:

Explanation:

Freezing point depression refers to the phenomenon that occurs when the freezing point of a solution is decreased due to the presence of ions or molecules. The freezing point depression is given by the formula:

 refers to the van't Hoff factor, which is the number of ions created by dissolving a single molecule of the solute. In this case, the van't Hoff factor is two because HCl will create two ions per molecule in solution.

 referes to the molality, which is the moles of solute per kilogram of solvent. We can rewrite our equation in these terms:

We know all of these terms, allowing us to solve:

This tells us that the freezing point of the solution is 11.16 degrees less than the freezing point of pure water.

Example Question #1 : Help With Properties Of Liquids

Which of the following best explains why a chef adds salt to the water when cooking pasta?

Possible Answers:

The salt raises the boiling point of the water, allowing the water to cook at a higher temperature

The salt raises the melting point of the water, making the cooking more efficient

The salt lowers the boiling point of the water, allowing the water to cook at a higher temperature

The salt lowers the melting point of the water, making the cooking more efficient

Correct answer:

The salt raises the boiling point of the water, allowing the water to cook at a higher temperature

Explanation:

Adding salt to water raises its boiling point. This allows the water to get hotter before evaporating. Boiling point elevation is a colligative property. Thus the increase in boiling point is proportional to the number of dissolved particles in solution, not the type of dissolved particles. 

Example Question #2 : Help With Properties Of Liquids

If a liquid has a high resistance to flow, it has a high __________.

Possible Answers:

viscosity

solubility

boiling point

freezing point

None of the answer choices are correct

Correct answer:

viscosity

Explanation:

By definition, viscosity is the measure of a liquid's resistance to flow. If a liquid has a high resistance to flow, it has a high viscosity. It may not necessarily have a high boiling point or melting point, nor be easily soluble in other liquids.

Example Question #3 : Help With Properties Of Liquids

Which of the following has the highest vapor pressure?

Possible Answers:

All of these have the same vapor pressure

Correct answer:

Explanation:

Vapor pressure relates to the molecules' ability to escape from their liquid form into a gaseous state. The weaker the intermolecular forces, the greater the vapor pressure (VP). Liquids with hydrogen bonding general have high VP. Bigger and longer molecules have larger VP then smaller ones. Methane does not hydrogen bond, and it is a relatively small molecule, thus many molecules will have enough energy to break the weak intermolecular forces and enter the gaseous phase. Both water and methanol can hydrogen bond. Propane has weak bonds like methane, but it is a larger molecule and will thus have a lower vapor pressure.

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