Basic Units + Gas Laws

Question 1

Equal values of
1 atmosphere

In Bar

Answer 1

1.01

Question 2

1 atmosphere = ?PSI

Answer 2

14.69

Question 3

1 atmosphere = ?kPa

Answer 3

100 (101.3)

Question 4

1 atmosphere = ?mmHg

Answer 4

760

Question 5

1 atmosphere = ?cm H2O

Answer 5

1020

Question 6

1 atmosphere = ?Pascal

Answer 6

101, 325

Question 7

How is SI unit for seconds standardised?

Answer 7

It is the duration for a certain number of oscillations of caesium-133 atom.

Question 8

How are the SI units for meter standardised?

Answer 8

Length light travels in vacuum in 1/300000000 of a second.

Question 9

How is mole standardised to?

Answer 9

Amount of substance that contains same number of particles as there are atoms in 0.012kg (12g) of carbon-12

Question 10

Regarding derived and non-SI units:
1. Derived units must always be expressed as base units? T/F

2. Velocity and speed have the same bad units? T/F

Answer 10

1. False, can be expressed as base units or combination

2. True

Question 11

What is the formula for kinetic energy?

Answer 11

1/2 mass x velocity squared

Question 12

Force formula

Answer 12

Mass x Acceleration

Question 13

Define pressure

Answer 13

Pressure is defined as the cumulative force generated, divided by the total area over which that force is applied.

Question 14

What is Boyles Law?

Answer 14

At a constant temperature, the volume of a gas at a given mass will decrease if it’s pressure is increased.

Volume of a given mass of gas varies inversely with absolute pressure.

Question 15

What is Charles Law?

Answer 15

At a constant pressure,
the volume of of a given mass varies with the absolute temperature.

Volume inversely proportional to Temp (Kelvin)

(Ie as temperature rises, gas moves more and hits sides of container therefore pressure would increase. To keep pressure constant volume of gas would have to increase to compensate.)

Question 16

What is Gay-Lussacs Law?

Answer 16

At a constant volume, the absolute pressure of a given mass varies with absolute temperature.

Question 17

What is the Kinetic Theory of gases?

What are the 4 postulates of Kinetic Theory?

Answer 17

• is a model of gas behaviour that describes an imaginary, ideal gas.
  1. Gases contain a large number of particles.
  2. Individual particles are moving in random directions at random speeds.
  3. Individual particles travel in a straight line.
  4. There are no attractive or repulsive forces between particles.

Question 18

What is Brownian Motion?

Answer 18

Provides a demonstration that fluids are really made up of fast moving particles.

Question 19

What does the Maxwell-Boltzmann curve describe?

Answer 19

At a given temperature, a gas of a higher molecular weight has particles moving at a lower average speed. Hence, the distribution of the curve shifts to the left.

Question 20

Is the speed of gas particles directly proportional to kinetic energy and why?

Answer 20

No because kinetic energy varies with the square of the speed is governed by the equation:

• kinetic energy = 1/2mv(squared)

Question 21

How does temperature effect the speed of a gas on a distribution curve and why?

Answer 21

Shifts to the right as speed increases with temperature.

Question 22

How would you describe temperature in relation to particles of gas?

Answer 22

Temperature is a reflection of the average kinetic energy of the particles of a gas.

Question 23

Graham’s Law?

Answer 23

Rate of diffusion of a gas is inversely proportional to the square root of its molecular weight.

Question 24

What is the combined gas law?

Answer 24

(Pressure x volume) / Temp = constant

Combination of three laws. Temp must always be in Kelvin but other units can be used for pressure and volume.

Question 25

What is Avogadro Principle?

Answer 25

States that equal volumes of all gases, at the same temp and pressure, must have the same number of molecules. Hence the measurement of mole- number of particles.

Question 26

What is a mole?

Answer 26

A quantity of a substance containing the same number of particles as there are atoms in 12g of carbon 12. This is equal to 6.022 x 10’23rd

Question 27

What is the value of R, the universal gas constant?

Answer 27

8.31 J K-1 mol-1

Question 28

What is the Ideal Gas Law

Answer 28

It combines Avogadro’s number and ideal gas law. PV/T = C Where C is the constant which is proportional to the amount of gas, n, which is Avogadros Law. The proportionality factor is the universal gas constant R therefore: C = nR

Question 29

What does Daltons Law of Partial Pressure state?

Answer 29

In a mixture of gases the pressure exerted by each gas is the same as that which it would exert if it alone occupied the container. PT = (n1 + n2...)RT

Question 30

What is critical temperature?

Answer 30

The temperature above which a substance cannot be liquefied however much pressure is applied.

Question 31

What is the critical temperature of oxygen? Nitrous oxide?

Answer 31

Oxygen: -119 degrees C Nitrous Oxide: 36.5 degrees C

Question 32

What is critical pressure?

Answer 32

Critical pressure is the saturated vapour pressure of a substance at its critical temperature.

Question 33

Regarding the behaviour a gas: 1. When does behaviour deviate from an ideal gas? 2. What is the weight of one mole of nitrous oxide and what volume would it occupy at STP? 3. What is the equivalent mass of one mole of oxygen and what volume would it occupy at STP?

Answer 33

1. When temperature falls and pressure rises 2. 44g is one mole, occupies 22.4L 3. 32g is one mole, occupies 22.4L

Question 34

Would one mole of oxygen at 1 atmosphere pressure and room temperature occupy 22.4L?

Answer 34

No because the rule is that one mole would occupy this volume at standard temperature - 273.15 Kelvin - not room temperature.

Question 35

True/False Regarding the ideal gas law PV = nRT 1. n must always be great than 1 2. Temperature must always be expressed in Kelvin 3. Measurements must always be taken at standard pressure and temperature 4. The unit of ideal gas is in moles

Answer 35

1. False, must be greater than or equal to zero. 2. True 3. False, hence the P and T in the equation as variables. 4. False, it is J K mol

Question 36

What is saturated vapour pressure?

Answer 36

It is the partial pressure exerted by the vapour which is in equilibrium with its liquid.

Question 37

What is Henry’s Law?

Answer 37

At a fixed temperature - the amount of a given gas dissolved in a given liquid is directly proportional to the partial pressure of the gas in equilibrium with the liquid.

Question 38

What are the Bunsen and Otswald solubility coefficients?

Answer 38

Two ways of describing how gases are dissolved in solution. Bunsen- the volume of gas corrected to STP and dissolved in a unit volume of a liquid at the temperature concerned where the patty oak pressure of the gas above the liquid is one atmosphere. Otswald- the volume of gas dissolved in a unit volume of liquid at temperature concerned. Otswald preferred by anaesthetists as it is not corrected to STP.

Question 39

How does knowledge of gases in solution explain why giving a patient fracture ribs and pneumothorax Entonox (nitrous oxide in oxygen) be risky?

Answer 39

The pneumothorax contains nitrogen and gas lower solubility than nitrous oxide, therefore nitrous oxide diffuses into the closed cavity faster than nitrogen diffuses out. This would increase pneumothorax volume.

Question 40

Define density

Answer 40

Mass per unit volume | P = kg/m’3

Question 41

How is the specific density of gas measured?

Answer 41

Relative to air. Specific density > 1 = more dense than air. < 1 = less dense than air. Liquids and solids are given relative densities to water.

Question 42

What is viscosity and what is it’s units?

Answer 42

Viscosity of the tendency of a fluid to resist flow, “fluid friction”, measured in Poise(P).