Because the mass and volume of the sample of the ideal gas are kept constant, a change in pressure causes only a direct change in the temperature. This can be derived from the following ideal gas equation:.

This problem requires us to substitute the moles of gas in the ideal gas law to mass over molar mass.

We can then isolate for the mass of chlorine gas in the vessel.

Chlorine is diatomic, so its molecular weight will be twice the atomic mass.

The temperature must be expressed in Kelvin.

Using these values, we can solve for the mass of chlorine gas in the vessel.

Since we have information about temperature and we are interested in changes in pessure, Gay-Lussac's Law will be used. This says that

The initial temperature and pressure are given (STP) meaning a temperature of  and a pressure of . There are other values for standard pressure but they have different units and since the problems requests an answer in units of  we must use the value of standard pressure with those units. Solving for the final pressure gives

Plugging in our variables gives

We want 3 significant figures since the temperature given has 3, so the final answer is

Since pressure is kept constant, we can directly compare the moles of gas in the container and volume using Avogadro's law. Since moles of gas and volume are on opposite sides of the ideal gas law, the two variables are directly proportional to one another.

Avogadro's law is written as follows:

First, we will need to convert the initial mass of gas to moles. It is important to remember that nitrogen gas is diatomic!

Use this value and the given volumes to solve for the final amount of gas in the container.

Avogadro's Law states that two gases at the same temperature and volume will have an equal number of molecules, and therefore the same number of moles.

It does not matter that helium has one atom per molecule while carbon tetrachloride has five atoms per molecule. Note that the given volume per mole of gas at STP is standard, and true for any gas. At STP, one mole of gas will always have a volume of 22.5L, regardless of its identity.

To find the number of neutrons, we must convert the moles to atoms by multiplying the moles by Avogadro's number .

Now looking at the periodic table, the neutrons per atom can be found by subtracting the atomic weight by the atomic number:

Thus there are 14 neutrons in each atom of aluminum.

The temperature of a sample during the process of a phase change will remain constant. Even though heat may be added or removed during this process, it is utilized to directly impact the formation and breaking of intermolecular interactions within the sample. The result is a change in the internal properties of the sample (the phase), with no actual change in temperature.

When a substance freezes it transitions from a liquid to a solid. The result is a much more ordered structure, as opposed to the fluidity associated with the liquid phase. Increasing order corresponds to a decrease in entropy because entropy is a measure of disorder.

When a substance freezes, the average kinetic energy of the particles decreases. This means that the particles will move more slowly. Most substances also contract when they cool to increase the organization of the molecules (crystallization). Thus, for most substances, particles will get closer together as they freeze. One notable exception is water, which expands as it freezes (the same mass of water that freezes into ice will float in liquid water due to an increase in volume).

The section point A is in is the solid portion of the phase diagram. At low temperatures and high pressures, substances form solids. Increasing the temperature while keeping pressure high, ice melts into water. Point G is in the liquid portion of the phase diagram.

Distillation is the process by which liquids are purified of impurities. Distillation first requires vaporization of liquids to become pure gases. The gases are then cooled and turned back into pure liquids via condensation into a separate container. A good distillation will remove all impurities from the liquid. This is why distilled water is used for chemical solutions; it does not contain ions or other impurities that could interfere with reaction.