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Atoms & Molecules In Motion Flashcards

1
Q

What are the four postulates of an ideal gas?

A
  1. Gases consist of large number of particles
  2. Individual particles are moving in random directions at random speeds
  3. Individual particles travel in straight lines between abrupt collisions
  4. No attractive or repulsive forces between particles
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2
Q

When do real gases deviate most from ideal gases?

A

When particles are close together I.e. low temp, high pressure

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3
Q

Name 2 ways real gases deviate from ideal gases (postulates)

A
  1. Real gas particles occupy small but finite volume (postulate 1 suggests volume of gas particles is negligible)
  2. Gas particles exhibit attractive forces for one another (postulate 4 says no attractive or repulsive forces)
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4
Q

What is brownian motion?

A

Physical phenomena in which some quantity is constantly undergoing small, random, fluctuations

In fluids (gas or liquid)

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5
Q

What is the Maxwell-boltzmann distribution?

A

Define the distribution of speeds for a gas at a certain temperature

(Kinetic theory of gas)
*can derive most probably speed and average speed

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6
Q

What effect does increase temp have on Maxwell-Boltzmann distribution curve?

A

Shifts peak (speed) to right (increased kinetic energy)

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7
Q

What effect does increased molecular weight have on Maxwell-Boltzmann distribution curve?

A

Shift peak to left
I.e. increased molecular weight = slower speed at same kinetic energy

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8
Q

Describe Boyles Law

A

As volume of gas decreases, pressure increases (at constant temp)

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9
Q

Describe Charles’ Law

A

At a constant pressure, the volume of a gas varies with its absolute temperature

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10
Q

What is Newton’s first law of motion?

A

In the absence of external forces, an object at rest remains at rest and an object in motion continues in motion with a constant velocity (at a constant speed and in a straight line)

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11
Q

What is Newton’s second law of motion?

A

F=ma
The acceleration of an object is directly proportional to net force and indirectly proportional to its mass

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12
Q

What is Newton’s third law of motion?

A

For every action there is an equal and opposite reaction

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13
Q

What is a newton?

A

The force that gives a mass of 1 kg an acceleration of one metre per second per second 

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14
Q

Define pressure

A

Pressure is the force per unit area i.e. the amount of force supplied to a surface.
Pressure = force/area

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15
Q

What is one Pascal?

A

One Pascal is the pressure of one Newton acting over an area of one square metre

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16
Q

What is atmospheric pressure in kPa?

A

 101.3

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17
Q

What is 1kPa in mmHg?

A

1kPa = 7.5mmHg

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18
Q

What is atmospheric pressure in:
- atm
- bar
- kPa
- mmHg
- cmH2O
- PSI

A

1 atm
1 bar
101.3 kPa
750 mmHg (75cmHg)
1020 cmH2O
14.7 PSI

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19
Q

Describe boyles law

A

V ~ 1/P
At constant temperature, the volume of a given mass of gas varies inversely with absolute pressure

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20
Q

What is a clinical application of Boyle law?

A

 you can use it to work out how much gas and oxygen cylinder will supply e.g. on transfer

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21
Q

Describe Charles’s law

A

V~T
Constant pressure the volume of a gas is proportional to the absolute temperature

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22
Q

 describe Gay-Lussacs Law

A

P~T
 at constant volume the absolute pressure of a given mass varies directly with absolute temperature

23
Q

What is the universal gas constant?

A

8.31 J K^-1mol^-1

24
Q

What is avogadros number

A

6.022x10^23

25
What is standard temperature and pressure?
1 atm (101.3 kPa) and 273.15 Kelvin (zero degrees Celsius)
26
What is Avogadro’s principal?
 equal volumes of all gases at the same temperature and pressure have the same number of molecules
27
What volume does one mole of any gas at standard temperature and pressure occupy?
22.4 Litres
28
What is the clinical application of Avogadro principle?
 the calibration of anaesthetic vaporisers
29
What is Dalton’s law of partial pressures?
 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
30
What is critical temperature?
 the temperature above which a substance cannot be liquefied however much pressure is applied
31
What is critical pressure?
Pressure needed to liquefy the gas at its critical temperature
32
What is the difference between gas and vapour?
A gas is above its critical temperature and therefore cannot be liquefied. Whereas a vapour is in gaseous form below critical temperature vapour can be liquefied if enough pressure is applied.
33
What is Henry’s law?
Had particular temperature the amount of gas dissolved in a liquid is proportional to the partial pressure of the gas in equilibrium with the liquid
34
What is the clinical application of Henry law?
Hyperbaric oxygen therapy
35
What is saturated vapour pressure?
The partial pressure exerted by a vapour at equilibrium
36
What is Henry’s Law?
The higher the pressure, the more dissolved gas (simplified version)
37
What is the partition coefficient?
The ratio of the amount of a given substance present in one phase compared with another (both phases being of equal volume and at equilibrium)
38
What are the 2 methods of describing gas solubility?
Bunsen - volume of gas corrected to STP dissolved in a unit volume of liquid at the temperature concerned where partial pressure of gas above the liquid if 1 atm Ostwald - the volume of gas dissolved in unit volume liquid at the temperature concerned
39
What is density?
Density is mass per unit volume Rho = m/v Units if density = kg/m^3
40
What is viscosity? And units of?
- the tendency of a fluid to resist flow - measured in poise (P)
41
What is a Newtonian fluid?
One in which viscosity is unaffected by shear or tangential stress Dependent solely on temp and pressure
42
What is density measure in
Kg/m^3
43
Does density or viscosity have a more marked effect on turbulent flow?
Density
44
Does density or viscosity have more marked effect on the flow at the base of a rotameter?
Viscosity - the base of rotameter has a narrow orifice around the bobbin causing laminar flow - which is more affected by viscosity than density
45
What type of flow meter device is a pneumotachograph? (Orifice and pressure)
Fixed orifice, variable pressure Device
46
Can a wright respirometer measure flow?
Only with addition of timing device Usually measures volume only
47
What does a bourdon gauge measure
Pressure
48
What is the boiling point of oxygen?
-183 degree C
49
What is the boiling point of helium
-269 degrees C
50
What is the boiling point of nitrous oxide?
-88 degrees C
51
What is the critical temperature of nitrous oxide?
36.5 degrees C
52
What is the critical temperature of CO2?
30 degrees C
53
What is the critical temperature of O2?
-118.6 degree C

Physics for anaesthetics (2 decks)

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