AP Chemistry : Solids, Liquids, and Gases
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Example Questions
Example Question #901 : Ap Chemistry
Hydrogen gas is being stored in a container. The pressure of the gas is suddenly doubled. What could NOT be an explanation for this sudden change?
A lab assistant left a bunsen burner on near the container, causing it to warm up.
A lab assistant squeezed the container into a storage closet, in order to make it fit.
A laboratory assistant thought it was warm in the lab, so he turned on the air conditioning system.
A lab assistant accidentally turned a nozzle, allowing more hydrogen gas to enter the container.
A laboratory assistant thought it was warm in the lab, so he turned on the air conditioning system.
When dealing with gas problems that have multiple factors but very little data is given, it is a good idea to use the ideal gas law to compare factors.
The ideal gas law is written as PV = nRT
This allows us to see how factors could affect the pressure in the container. By lowering volume, we would see that pressure increased. If more gas was allowed into the container (increasing n), the pressure would increase as well. If we lower the temperature (lower T), then pressure should decrease as well. As a result, pressure rising due to a drop in temperature does not make sense in this question.
Example Question #1 : Phases Of Matter
If you create a perfect vacuum and place a glass of water into the vacuum at room temperature, what will happen to the water?
The water will boil very rapidly and then stop
The water will freeze
Nothing will happen
The water will float about the vacuum
The water will boil
The water will boil
Boiling occurs when the vapor pressure exceeds the air pressure. There is no air pressure in a vacuum, so water at any temperature will boil in a vacuum.
Example Question #131 : Solutions And States Of Matter
Boiling points at standard temperature and pressure:
Methanol-
Toluene-
Water-
Methylene chloride-
Dimethylsulfoxide-
Of the five compounds given, which will have the highest vapor pressure at standard temperature and pressure?
Methanol
Water
Toluene
Methylene chloride
Dimethylsulfoxide
Methylene chloride
A liquid will boil when its vapor pressure increases to match the pressure of its environment. By this logic, a liquid with a higher vapor pressure will be closer to boiling. Liquids with low boiling points thus have greater vapor pressures.
Of the given compounds, methylene chloride has the lowest boiling point, meaning it will also have the highest vapor pressure.
Example Question #1 : Phases Of Matter
Oil and vinegar is a very popular salad dressing. It also is commonly used for dipping bread. The main component of the oil phase is olive oil, while the main part of the vinegar portion is aqueous acetic acid.
When oil and vinegar salad dressing is allowed to stand at room temperature, two distinct phases are observed. The main explanation for this phenomenon is the difference in _________ of the two phases.
acidity
polarity
solubility
density
buoyancy
polarity
Olive oil, like most oils, is non-polar, while aqueous acetic acid is very polar. These two phases do not mix because of their different solvent polarities.
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