Calculste the r.m.s. speed of hydrogen molecules at s.t.p.
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The kinetic theory can be used to calculate the r.m.s. velocity of gas molecules.
Kinetic energy of a gas molecule = ½ mc2,
where m is the mass and c is the velocity.
Kinetic energy of a gas = ½ mN c' 2, where N is the number of molecules and c' the root mean square velocity.
In the equation PV = (1/3) mN c' 2, substitute PV = RT for one mole of a gas and mN = M the molar mass of the gas in kg.
For hydrogen, mN = M = 2.02 x 10-3 kg/mol,
Substituting in PV = (1/3) mN c' 2 = RT we get
c'2 = 3 x 8.31 x 273 /( 2.02 x 10-3 )
The r.m.s. velocity c' = [ 3 x 8.31 x 273 /( 2.02 x 10-3 )]½.
= 1.84 x 103 m/s.
Kinetic energy of a gas molecule = ½ mc2,
where m is the mass and c is the velocity.
Kinetic energy of a gas = ½ mN c' 2, where N is the number of molecules and c' the root mean square velocity.
In the equation PV = (1/3) mN c' 2, substitute PV = RT for one mole of a gas and mN = M the molar mass of the gas in kg.
For hydrogen, mN = M = 2.02 x 10-3 kg/mol,
Substituting in PV = (1/3) mN c' 2 = RT we get
c'2 = 3 x 8.31 x 273 /( 2.02 x 10-3 )
The r.m.s. velocity c' = [ 3 x 8.31 x 273 /( 2.02 x 10-3 )]½.
= 1.84 x 103 m/s.
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