Gases Flashcards
Does Random motion occur in Gases?
Yes. The molecules are not constrained
How is kinetic energy proportional to temperature?
An increase in temperature will also increase kinetic energy and vice versa. this means collisions will also be increased/ decreased
What is the relationship between gasses, pressure and volume?
The volume of a given gas is inversely proportional to the pressure (provided constant temp)
P1V1=P2V2
How does inhalation and exhalation occur when humans breathe?
Inhalation = occurs when the ribcage expands and the diaphram moves downward, increasing the volume and decreasing the pressure
Exhalation = the rib cage contracts and the diaphram moves up, decreasing volume and increasing pressure
- the expansion of the chest cavity reduces pressure in the intrapulmonary and intrapleural cavity, hence causing the lungs and alveoli to expand with pressure
How is lung collapse prevented?
The difference in pressure between the intrapleural and intrapulmonary cavities stop lung collapse
When does Boyle’s law apply?
Only for gases that are not too dense and not close to boiling point
What is the relationship between gas volume and temperature?
V1/V2=T1/T2
What is Charle’s Law?
The volume of a fixed quantity of gas at constant pressure is proportional to temperature
When do gases liquify? and what is absolute 0?
at low temperatures, absolute 0 = 273.15 degrees
How to calculate the temperature in Kelvins?
Temperature in Celcius + 273.15
What is Guy Lussac’s law?
When volume is constant, the pressure is directly proportional to temperature
when T is in Kelvins = P1V1/T1 = P2V2/T2
What variables are needed to define the state of gases?
temp
pressure
volume
number of mols of gas
What is the Ideal Gas Law?
PV=nRT
the volume of an enclosed gas increases in direct proportion to the mass of gas present
What is Standard temperature and pressure (STP)?
t=273.15K
P= 101.3kPA
volume = 22.4L per mol
What does Avogadro’s number say?
Equal numbers of gases at the same pressure/ temperature must have the same number of molecules
How can partial pressure help to identify the ideal gas law?
PV = nRT
(P1+P2+P3 etc) XV = (n1+n2+n3 etc) XRT
How does concentration effect flow rate?
The greater the difference in concentration per unit distance, the greater the flow rate
How does water equalise partial pressure?
Water flows one way until the pressure of water is the same on both sides (equil), and there is no net flow of water
How can the osmotic pressure due to solute molecules be given?
pi=(n/v) X RT
How does partial Pressure effect the number of molecules striking the surface?
They are proportional to one another
- eg: If we compress the gas to a smaller volume, the same number of molecules are now acting against a smaller surface area, so the number striking per unit of area, and thus the pressure, is now greater
What is dynamic equilibrium?
Between gas and liquid phases, as many molecules of gas that enter the solution also leave it
What is Henry’s law?
The equilibrium concentration of dissolved gas is proportional to the partial pressure of that gas above the liquid
Describe how Nitrogen Narcosis is caused?
- When diving deep underwater breathing high pressure air, N2 dissolves in the blood in very large concentrations
- If the diver rises quickly, pressure of air is reduced, and the partial pressure of nitrogen drops and causes bubbles of N2 to form in the bloodstream which can cause death
What is the rate of vapouration dependent on?
temperature
What is saturated vapour pressure?
the equilibrium pressure of a gas phase above a liquid of the same molecules
How can water’s SVP change?
at body temp (37) SVP= 6kPA
at 100 degrees SVP= 101kPA
at boiling point of any liquid SVP= atmospheric pressure
Can the ideal gas law be applied to SVP?
No. You must use the known SVP values for water vapour and apply the ideal gas law to any remaining gases
