Copyright 2012 CFT GAS/1 ISO 24801-2 / EN 14153-2 "AUTONOMOUS DIVER" Gas Laws.

Copyright 2012 CFT GAS/1ISO 24801-2 / EN 14153-2 "AUTONOMOUS DIVER"

Gas LawsGas Laws

Copyright 2012 CFT GAS/2

We will cover Boyle's Law Dalton's Law Henry's Law Charles' Law


Boyle’s Law

“At a constant temperature, the volume of a given mass of gas varies inversely with the absolute

pressure”


Dalton's Law

“In a mixture of gases, each constituent gas exerts a Partial Pressure in proportion to its percentage

of the mixture”


Dalton's Law(Example)

Pure air at 1 bar pressure Air consists 79% nitrogen and 21% oxygen Partial pressure of nitrogen

= 0.79 bar (ppN2 = 0.79 bar) Partial pressure of oxygen

= 0.21 bar (ppO2 = 0.21 bar)


Henry's Law

"The amount of gas that dissolves in a liquid is proportional to the partial pressure of the gas in

contact with the liquid"(Providing temperature is constant)


Henry's Law

Highpressure

Excessgas

dissolvedin liquid

Cap sealed


Henry's Law

Cap removed

Reducedpressure

Reduced amountof gas

can dissolvein liquid

Gas Bubblingrushing out

of liquid


Charles' Law

"At constant pressure the volume of a gas varies directly with the absolute temperature"

or"At constant volume the pressure of a gas varies

directly with the absolute temperature"


Charles' Law(Example)

Cylinder pressure = 232 Bar (P1) Original temperature = (20°C) 293 K (T1) Temperature increase to (70°C) 343 K (T2)


Charles' Law(Example)

IfP1

T1

=P2

T2

P2 = P1 x T2

T1

P2 = 232 x (273 + 70)

(273 + 20)

= 271 Bar

New pressure in cylinder = 271 Bar


Gas Laws Summary Boyle's Law

Relates pressure and volume Dalton's Law

Defines partial pressure exerted by individual gases in a mixture of gases

Henry's Law Defines the solubility of gases in a liquid

Charles' Law Relates change in pressure and volume of gases to

changes in temperature

Copyright 2012 CFT GAS/13ISO 24801-2 / EN 14153-2 "AUTONOMOUS DIVER"

QuestionsQuestions


Pressure and volume are inter-related by:

a) Charles' Law?b) Boyle's Law?c) Henry's Law?


Dalton's Law deals with:

a) Pressure changes due to temperature increases?

b) Volume changes due to temperature increases?c) Partial pressures of gases?


The Gas Law used to explain the Bends is:

a) Charles'? b) Dalton's?c) Henry's?


At a depth of 20 metres in sea water the partial pressure of

nitrogen in the air supply will be _____ times the partial pressure

which it is at the surface:a) Two?b) Three?c) Four?


Exposing a full diving cylinder to excessive heat is not

recommended because:a) The paint may deteriorate and allow rust?b) The rubber seals involved may perish and give

rise to air leaks?c) The internal air pressure may rise excessively?


Exposing a full diving cylinder to excessive heat is not

recommended because:a) The paint may deteriorate and allow rust?b) The rubber seals involved may perish and give

rise to air leaks?c) The internal air pressure may rise

excessively?


Serious diving ailments such as Nitrogen Narcosis are explained

using:a) Boyle's Law?b) Charles' Law?c) Dalton's Law?


The analogy of the bubbles forming in a fizzy drink when the

bottle is opened is used to explain:

a) The Bends?b) Oxygen Starvation?c) Nitrogen Narcosis?

Copyright 2012 CFT GAS/1 ISO 24801-2 / EN 14153-2 "AUTONOMOUS DIVER" Gas Laws.

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