High School Chemistry : Help with Properties of Liquids
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Example Questions
Example Question #4 : Phases Of Matter
Which phase of matter has a definite volume, but no definite shape?
Gas
Liquid
Solid
All phases have these qualities
Liquid
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 #1 : Help With Properties Of Liquids
What is the freezing point of three moles of HCl dissolved into 1kg of water?
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:
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?
The salt lowers the boiling point of the water, allowing the water to cook at a higher temperature
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 melting point of the water, making the cooking more efficient
The salt raises the boiling point of the water, allowing the water to cook at a higher temperature
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 __________.
freezing point
solubility
boiling point
viscosity
None of the answer choices are correct
viscosity
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 #1 : Help With Properties Of Liquids
Which of the following has the highest vapor pressure?
All of these have the same vapor pressure
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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