Amount Of Substance (gases)

avatar
Created by
Ghaidaa Chihi

Cards (7)

  • Molar gas volume = volume per mole of gas molecules at a stated temperature and pressure (usually RTP)
  • Room temp is about 20°C and 101KPa
  • Molar gas volume = volume(dm3) / moles
  • Ideal gas Exchange = pV = nRT
    p - pressure, Pa
    V - volume, m3
    n - moles, mol
    R - ideal gas constant, 8.314
    T - temperature, K
  • cm3 - m3 = x10 -6
    dm3 - m3 = x10 -3
    °C - K = +273
    KPa - Pa = x10 3
  • Molar Gas Volume at RTP is 24 dm3
  • Stoichiometric ratio Question:
    Nitrogen fertiliser A has the composition of mass Na: 27.1% ; N: 16.5% ; O: 56.4%
    On heating, 3.40g of A decomposes into Sodium Nitrite, NaNO2 and oxygen gas
    • calculate empirical formula of A
    n(Na) = 27.1 / 23.0 = 1.18
    n(N) = 16.5 / 14.0 = 1.18
    n(O) = 56.4 / 16.0 = 3.53
    1.18:1.18:3.53
    1:1:3 NaNO3
    • Write an equation
    2NaNO3 -> 2NaNO2 + O2
    • Calculate volume of oxygen gas at RTP
    n(NaNO3) = 3.40 / 85 = 0.04
    n(O2) = 2:1 ratio = 0.04 / 2 = 0.02
    0.48dm3= 24 x 0.02