Chromotography

Question 1

Kinetic Theory of Gases

Answer 1

1. A sample of gas contains a large number of particles in constant random motion.
2. The distance between gas molecules is much greater than the size of the molecules, so the volume of the molecules themselves is essentially zero.
3. Intermolecular interactions are so weak in the gas state that they can be disregarded.
4. Gas molecules have only elastic collisions with one another and with the walls of the container (no energy is lost in collision)
5. The average kinetic energy of the molecule depends on the temperature.

Question 2

Ideal Gas

Answer 2

The kinetic theory of gases is an approximation at moderate temperatures and pressures. An ideal gas is one that completely follows the kinetic theory of gas. This means that an ideal gas is also an approximation.

For temperatures near room temperature, and pressures near atmospheric pressure, many of the gases are almost perfectly ideal.

Question 3

Temperature

Answer 3

A higher temperature means the particles have higher kinetic energy, and a lower temperature means that they have a lower average kinetic energy.

Question 4

Pressure (P)

Answer 4

In a closed container, individual molecules are constantly hitting and bouncing off the container walls, imparting a small force. So the pressure will be higher if the molecules are imparting a larger force or if there are a lot of molecules hitting the container per unit area.

In a flexible container such as a balloon, the force of the molecules hitting inside of the balloon hold the balloon inflated. The force of each impact is small, but the sheer number of collisions create enough force to keep the balloon open. Standard unit for pressure is Pascals (Pa) or kilopascals (kPA), atmospheres (atm) or pounds per square inch (psi). SI unit is pascal (Pa).

Question 5

Standard Temperature and Pressure (STP)

Answer 5

Since the total volume that a gas occupies is made up primarily of the empty space between particles, the actual sizes of the particles are negligible. This means that equal volumes of all gases at the same temperature and pressure will always contain equal number of particles. STP IS 0 DEGREES C, AND 100 kPa. At STP, 1 mole of gas holds 22.7L.

Question 6

Gay-Lussac’s Law

Answer 6

At a constant volume and same number of moles, the pressure of an ideal gas is directly proportional to its absolute temperature.

P1/T1 = P2/T2

Question 7

Boyle’s Law

Answer 7

Boyle’s law states that a constant temperature the volume of a sample of gas is inversely proportional to the pressure.

P1V1 = P2V2

Question 8

Charles’ Law

Answer 8

At a fixed pressure for a fixed mole, gas volume is proportional to temperature.

V1/T1 = V2/T2

Question 9

Avogadro’s Law

Answer 9

At constant pressure and temp, gas volume is proportional to the moles of gas. More moles will give you greater volume.

V1/n1=V2/n2

Question 10

Ideal Gas Law

Answer 10

PV = nRT

R is a constant