Ideal Gas Law

The universal gas constant is defined as as:

Pick the right value and units for based on the other units in the equation. As long as this is correct, the answer will be correct as well.

where:

• is the universal gas constant
• is the temperature in kelvin
• is the volume
• is the pressure
• is the number of moles

(see Avogadro and Gasses, Measuring a Gas)

The ideal gas law does not account for the type of gas present, and makes the following assumptions:

• There are no Intermolecular Forces between gas molecules
• Gas molecules have no molecular volume

The ideal gas law is only a good approximation at high temperature and low pressure

of nitrogen dioxide gas in a container holds at . What is the temperature in the cylinder?

solution

A UT student accidentally swallows a drop of liquid oxygen, , which has a density of . Assuming that the drop has a volume of , approximately what volume of gas will be produced in the students stomach at body temperature () and a pressure of ?

solution

Determine the mass of the swallowed:

Determine number of moles:

Use ideal gas law:

Two evacuated bulbs of equal volume are connected by a tube of negligible volume. One of the bulbs is placed in a constant-temperature bath at and the other bulb is placed in a constant-temperature bath at . Exactly 1 mole of an ideal gas is injected into the system. Calculate the final number of moles of gas in each bulb.

solution
We know:

We also know so we can write:

First, solving the system for :

Then for :

Nitrogen oxide () can be produced by the reaction of sulphuric acid with sodium nitrite according to the following balanced equation:

What volume (in L) of aqueous should be used to produce of at and ?

solution
Use ideal gas law to find the number of moles of :

Use the given molarity to find the number of moles of :

Equate the moles to solve for volume:

A sample of potassium chloride-potassium chlorate () mixture is decomposed by heating. of is produced, measured at and .

What is the mass percent of in the original mixture?

solution
We have:

Find the number of moles of produced:

Find the number of moles of produced:

Find the mass of produced:

Find the mass percentage from the given mass:

A sample of gaseous compound containing boron and hydrogen occupies at and . When the compound is ignited in excess of oxygen all its hydrogen is recovered as of and all the boron is left over as .

Empirical formula:

What is the molecular formula, and the molar mass of the boron-hydrogen compound? What is the mass of produced in the reaction?

solution
Find the number of moles of the gaseous compound:

Find the molar mass:

Molar mass of :
Ratio of molar masses:
Molecular formula: .

Chemical equation:

and have a 1:1 ratio, so the number of moles is .