physics 4 Flashcards
What does Avogadro’s Principle state?
Equal volumes of all gases, at the same temperature and pressure, have the same number of molecules. (express in moles)
a quantityof a substance containing the smae number of particles as there are atoms in 12g of carbon 12 (6.022 x10^23)
What is a mole in terms of quantity?
A mole is the quantity of substance containing the same number of particles as there are atoms in 12 g of carbon 12.
How many particles are in one mole?
6.022 x 10^23.
What volume does one mole of any gas occupy at standard temperature and pressure?
22.4 litres.
Fill in the blank: A mole is equal to _______ particles.
6.022 x 10^23.
True or False: Different gases have the same molecular weights.
False.
What is the standard temperature and pressure (STP) for gases?
1 atm and 273.15 K.
Why is it easier to express gas quantity in terms of molecules rather than mass?
Because different gases have different molecular weights.
At STP, how many litres does 1 mole of gas occupy?
22.4 litres.
what is the combined gas law?
PV/T =constant
What is the ideal gas law?
PV=nRT
R= 8.31
PV/T = constant. The value of the constant is number of moles of gas present (n). This is multiplied by
the universal gas constant (R) which represents the behaviour of a single mole of gas and has the
value of 8.31 J K-1 mol-1. OVERALL:
PV = nRT
A full cylinder of nitrous oxide contains 3.4 kg of nitrous oxide, but how much gas are you able to get
out of the cylinder?
Nitrous oxide molecular weight = 44.
Therefore, 1 mole N2O = 44g and occupies 22.4L.
3400g/44 = 77.2. There are 77.2 moles in the cannister
77.2 x 22.4 = 1730L
Don’t forget the residual volume which will be left!
what is daltons law of partial pressures?
the pressure exerted by each gas is the same as that which it would exert if it occupied the container alone
e.g
PV = (n1 +n2 …) x RT
In a cylinder of air at 100kPa, there is 20.9% oxygen and 79% nitrogen. The total pressure would be
100kPa but the 2 gases will exert 20.9kPa and 79kPa respectively.
what is the critical temp of N2O
36.5°C,
critical temp is the temp above which a substance cannot be liquified however much pressure is applied.
what is the critical temp of O2
-119°C
what is the humidity of air entering upper trachea?
What humidity can HME filter achieve and how?
what humidity do the following achieve?
-cold water bath/bubble humidifier
-hot water bath
-neb (gas- bernoulli effect)
-Neb (ultrasonic)
34 g/m3
(compared to 17g/m3 at room temp)
HMEF can achieve max 35g/m3 using internal foam impregnated with hygrosopic substance. when water vapour passes through it condenses and provides latent heat to the HME so that the next inhale will be warm and absorb the moisture
It is cheap and can have a bacterial/viral filter.
however increase resistance in the breathing
70% efficiency.
what humidity do the following achieve?
-cold water bath/bubble humidifier- 10g/m3
-hot water bath- 40g/m3
-neb (gas- bernoulli effect) 50-60 g/m3
-Neb (ultrasonic)- 80-90 g/m3
this has optimal effectiveness at 100% efficiency but may be too effective and cause water overload, especially in children
where are the following droplet sizes deposited?
1 micron.
5 microns
20 microns
Droplet size is important when providing humidification:
1 micron – alveoli and exhaled.
5 microns – trachea (does not humidify the distal airways)
20 microns – condensation on equipment
how much does solute raise boiling point by
how much does it depress freezing point by?
1 mole of solute dissolved in 1kg of water elevates boiling point by 0.51OC which is why potatoes
cook quicker in boiling water with salt added!
1 mole of solute dissolved in 1kg of water reduces freezing point by
1.86oC. This is the reason why salt is spread on icy roads!
how to measure ph
what does laser stand for?
LASER: acronym for light amplification by stimulated emission of radiation.
