Stoichiometry and the combustion of fuels

Question 1

List 3 properties explained by the kinetic molecular theory

Answer 1

• Gases are composed of small particles with much empty space between them
• Gas particles move rapidly in random motion, often colliding with other gas particles and the
  surface of the container
• Total kinetic energy remains the even when kinetic energy is transferred from one particle to
  another upon collision
• The weak intermolecular forces are negligible
• When the temperature of gas particles rise and or lowers it changes the speed of their motion, i.e.
  the average kinetic energy of a gas is proportional to its temperature.

Question 2

What happens when gas is put into a container?

Answer 2

It occupies all of the space around them (because of the properties)

Question 3

Why is the gas density low compared to liquids and solids?

Answer 3

Because the particles in the gas are much more widely spread and spaced apart.

Question 4

Why does gas take up space in the container differently to water?

Answer 4

• The particles in gas are much more spread out then in other states
• Gases mix together readily
• The particles of gas move independently of each other

Question 5

what is pressure and what affects gas pressure

Answer 5

Pressure is the amount of force exerted per unit of area on a surface
Gas pressure is the force (i.e. amount of collisions) that the gas exerts on the walls of a container.
Note – The total pressure of a mixture of gas is the sum of the partial (individual) pressures of each gas in the mixture.

Question 6

In what case are volume and temperature proportional?

Answer 6

As the temperature of a gas increases so does the average kinetic energy of the molecules. The pressure
will thus be increased. This can cause the volume of the gas to increase, as the pressure may stay constant
with the container expanding, e.g. in a balloon or syringe. (Or the pressure may increase if the volume of
the container is fixed). As the temperature of a gas increases so does the volume proportionally.
V ∝T or
V
_
T = k

Question 7

How do volume and amount of gas relate?

Answer 7

A change in the volume of a gas will proportionally change the amount of a gas in moles
V ∝ n or
V
n = k

Question 8

How does the space 1 mol of a gas changes from gas to gas?

Answer 8

One mole of any gas occupies the same volume as another when under the same conditions.

Question 9

what does SLC stand for? and what are the standards? How do gases behave in SLC conditions?

Answer 9

Standard Laboratory Conditions

At SLC:
Temperature = 25°C (298K)
Pressure = 100 kPa
At SLC most gases behave like an ideal gas and therefore have a molar volume close to that of an ideal gas
Vm (at SLC) = 24.8 L mol
−1

Question 10

What is the universal gas equation?

Answer 10

V ∝ nT
_
P
or PV = nRT

Question 11

What is R in the universal gas equation?

Answer 11

R is the gas proportionality constant 
R = 8.31 J K−1
mol
−1
 when:
P = kPa
V = L
n = mols
T = k