Calculate the # of moles of gas at STP in each of the following volumes.
a)168 dm^3
b)3.50 x 10^3 cm^3
2007-04-04 17:04:46 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Chemistry
You must use the ideal gas law to solve this:
PV = nRT
where P=Pressure, V=Volume, n=moles, R=gas constant, T=Temperature.
solve for n,
n=(PV)/(RT)
conditions at STP are P = 1.01 x 10^5 Pa, T = 273.15K
a) Change volume to m^3,
168 dm^3 x 1m^3/1000dm^3 = 0.168m^3
n = 1.01x10^5Pa (0.168m^3) / (8.31 m^3 *Pa/(K mol) * 273.15 K)
n = 7.47 moles
b) 3500 cm^3 = 0.0035m^3
n = 1.01x10^5Pa (0.0035m^3) / (8.31 m^3 *Pa/(K mol) * 273.15 K)
n = 0.156 moles
2007-04-04 17:21:42 · answer #1 · answered by Nat X 3 · 0⤊ 0⤋
Just form some ratios. Remember that 1 mole of gas= 22.4 L or 22,400 cm^3, or 22.4 dm^3. Ratios are:
1 mole/ selected volume for mole = x moles/ volume given.
2007-04-05 00:11:29 · answer #2 · answered by cattbarf 7 · 0⤊ 0⤋
At STP: Vm=22.4 dm
& Vm indicates the volume of 1 mole gas.
a) n = 168/22.4 = 7.5
b) v=3.5*10^3*10^-3= 3.5 dm
n= 3.5/22.4=0.15625
GOOD LUCK!
2007-04-05 10:56:32 · answer #3 · answered by Master of Chemistry 2 · 0⤊ 0⤋
assume molar gas volume at s.t.p. is 22.4 dm^3/mol.
a) 7.5 mol
b) 0.15625 mol (your units need to be converted to dm^3)
2007-04-05 00:12:15 · answer #4 · answered by ong_joce 2 · 0⤊ 0⤋