gaseous state Flashcards
what is the ideal gas equation
PV = nRT
what units must the ideal gas equation be in?
pressure — Pa
volume — m³
temperature — K
how to convert celcius to kelvin
kelvin = temp in celcius + 273
how to convert pressure to Pa?
1atm = 101325 Pa
1bar = 100000Pa
1kPa = 1000Pa
how to convert volume to m³?
1cm³ = 10⁻⁶cm³
1dm³ = 10⁻³cm³
how to use the ideal gas equation to determine Mr
PV = (m/Mr) RT
what is the combined gas equation?
P1V1/T1 = P2V2/T2 if n is kept constant
how to calculate total pressure of a mixture of gases?
total pressure = total moles x (RT/V)
what are the 3 assumptions about ideal gases?
- gas particles have negligible volume compared to the volume of the container
- intermolecular forces of attraction between gas particles are negligible
- collisions between gas particles & their collisions with the walls of the container are perfectly elastic (no net gain or loss of ke) (least important)
what are conditions for real gases to behave ideally?
low pressure and high temperatures
why do real gases behave ideally at low pressure?
low pressure = gaseous molecules relatively far apart. vol of molecules negligible compared to vol of container + intermolecular forces are negligible = gas molecules can be approximated to have negligible volume
why do gases behave ideally at high temperatures?
high temp = enough ke to overcome imf = can be considered insignificant = behave like ideal gas
why do real gases deviate at high pressures?
high pressure = vol of container decreases = molecules pushed closely together, taking up significant portion of container vol = less space in which molecules move = no longer valid to assume vol is negligible compared to container vol = gas deviates from ideal behaviour
also, gas particles close together = interact with one another = imf not negligible
why do real gases deviate at low temperatures?
low temp = ke decrease = particles move more slowly = imf more significant + collisions become inelastic = particles can no longer overcome imf = real gases liquefy
how does strength of intermolecular forces affect deviation?
the stronger the intermolecular forces present, the greater the extent of deviation
