IDEAL GASES Flashcards
1
Q
- What is the atmosphere composed of?
A
- Nitrogen (N2)
- Oxygen (O2)
- Water Vapour
(this depends on the local humidity levels)
2
Q
- What are three properties of gases?
A
- they are miscible
(they mix together) - they form homogenous mixtures
- they are compressible
3
Q
- Why do water and oil not mix together when they are in a liquid state?
A
- oil is less dense than water
- it will rise above the water
- water is more dense than oil
- it will sink below the oil
- they have different intermolecular forces between
their particles
4
Q
- In which state do oil and water mix together?
A
- in a gaseous state
5
Q
- What results in the properties of gases?
A
- the large distances between the gas particles
- this limits the interactions that are possible between
the particles
6
Q
- What is air composed of?
A
- 0.1% volume of gas particles
- 99.9% empty space
7
Q
- How is gas pressure calculated mathematically?
A
- it is the force divided by the given area
- the units of force are Newtons
- the units of area are m²
- the units of pressure is Pascals (Pa)
8
Q
- How else can Newtons be written?
A
- kg m / s²
9
Q
- How else can Pascals (Pa) be written?
A
- N/m²
- kg / (ms²)
- pascals are an extremely small unit
10
Q
- How would we work out the Gas pressure in this diagram?
- the column of the Earth’s atmosphere has a
dimension of 1m x 1m - this is estimated to have a mass of 10 300kg
- the column of gases is pressing down on the surface
of the Earth at sea level - this creates the atmospheric pressure
- the area of the column is 1.00m²
A
- P = m x g / A
- the gravitational force is calculated as F = m x g
- g = Earth’s gravitational constant
- g = 9.8m.s⎺²
∴P = 10 300 kg x 9.81m.s⎺² / 1.00m²
NB:
- if we go to a high mountain
- the height of the column is smaller
- this gives a reduced mass
- it also gives a reduced atmospheric pressure
11
Q
- Why is Mercury harmful to your health?
A
- it is neurotoxic
- it destroys the neurons in oyur brain
12
Q
- What is a Barometer?
A
- it is a weight measuring device
- it measures the weight of the atmospheric gases acting
on the Earth - it is a crude instrument
- it is used for measuring atmospheric pressures
13
Q
- How do we set up a Mercury Barometer?
A
- we fill up a bowl with liquid mercury
- we fill a glass test tube completely with mercury
- we place the glass test tube with the opening facing
downwards - the test tube is placed inside the bowl with Mercury
14
Q
- How does a Mercury Barometer work?
A
- gravity pulls down on the Mercury in the test-tube
- the mercury moves down the test tube
- this creates a vacuum at the top
- the atmospheric pressure is also pushing down on the
liquid mercury in the bowl - this pushes the liquid up into the test tube
15
Q
- How do we express atmospheric pressure using a Mercury Barometer?
A
- when a balance is reached between the forces in the
Mercury barometer - the height of Mercury in the test tube is measured
- in this case it is 760mm
- this is the atmospheric pressure