S1.5 Ideal gases Flashcards
what does the kinetic theory of gases say?
molecules in gases are constantly moving
what are the 5 assumptions of the theory?
gas molecules move fast and randomly; molecules have negligible volume; no intermolecular forces between gas molecules; no KE lost when there’s elastic collisions; temp of gas is directly proportional to average KE of the molecules
what does the volume that a gas occupies depend on?
it’s pressure and temp
what does decreasing the volume of a gas do?
what does the volume of any ideal gas at any given temp or pressure depend on?
no. of particles present
when do gases deviate the most from ideal behaviour?
high pressure and low temperature
why would a real gas behave differently at low temps?
because it would liquefy and then freeze(=large decrease in volume), ideal gases can’t liquefy bc there’s no forces between the molecules
what is STP?
273.15K and 100kPa
3 steps for determining the molar mass of a gas
weight a lighter gas refill canister, release some gas into measuring cylinder and record volume of gas produced, dry gas canister and re-weigh
how can you get a more precise answer with the molar mass practical?
using a 3 dp electronic balance or collecting a larger volume of gas
what is a systematic error?
error introduced by the apparatus or procedure=loss of accuracy
what are the 2 systematic errors in the molar mass practical and what does it mean for the results?
some gas escaped so recorded volume was lower than expected, canister not completely dried after removing it from water so there would be extra mass and the mass of the gas would appear to be smaller than the mass actually released from the canister
