S1.5 Ideal gases

Question 1

what does the kinetic theory of gases say?

Answer 1

molecules in gases are constantly moving

Question 2

what are the 5 assumptions of the theory?

Answer 2

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

Question 3

what does the volume that a gas occupies depend on?

Answer 3

it’s pressure and temp

Question 4

what does decreasing the volume of a gas do?

Question 5

what does the volume of any ideal gas at any given temp or pressure depend on?

Answer 5

no. of particles present

Question 6

when do gases deviate the most from ideal behaviour?

Answer 6

high pressure and low temperature

Question 7

why would a real gas behave differently at low temps?

Answer 7

because it would liquefy and then freeze(=large decrease in volume), ideal gases can’t liquefy bc there’s no forces between the molecules

Question 8

what is STP?

Answer 8

273.15K and 100kPa

Question 9

3 steps for determining the molar mass of a gas

Answer 9

weight a lighter gas refill canister, release some gas into measuring cylinder and record volume of gas produced, dry gas canister and re-weigh

Question 10

how can you get a more precise answer with the molar mass practical?

Answer 10

using a 3 dp electronic balance or collecting a larger volume of gas

Question 11

what is a systematic error?

Answer 11

error introduced by the apparatus or procedure=loss of accuracy

Question 12

what are the 2 systematic errors in the molar mass practical and what does it mean for the results?

Answer 12

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