Chem Gas Worksheet 2, KEY Block:___ Teacher:______ Name:_____________________________
0.987atm=750.1mmHg=100kPa=14.5psi. 24.8L/mol gas @SATP (100Kpa, 298.15K.) K.E.=mv2/2.
1. Molecular kinetic energies. Temperature measures the average molecular translational kinetic energy.
T is directly proportional to
K.E.
a. A molecule at 2K has __2__ times as much kinetic energy as a molecule at 1K.
b. A molecule at 600.K has __3.00___ X as much K.E. as a 200.K molecule.
c. A 1150K molecule has __4.21____ X the K.E. of a 273K molecule.
d. The average molecular kinetic
energy of molecules at 530K is ___6.9___ X the ave. molecular K.E. of molecules at 77K.
e. A 35oC molecule has ___1.1___ X the K.E. of a 0oC molecule.
f. The average molecular K.E. of
molecules at -125oC is __0.617______ X that of molecules at -33oC.
2. Molecular velocities vs. temperature; for the same mass, velocity is proportional to the SQUARE ROOT
T1
V1
of the temperature,
“hotter is faster”

T2
V2
a. A 400.K Ar molecule has ___4.00___X the K.E. of a 100.K Ar molecule because it is going __2___X faster.
b. A 750.K Ne molecule goes _1.73_____X faster than a 250.K Ne molecule.
c. An H2O molecule at 50.oC goes ___1.2____ X faster than one at –50.oC
d. A Si atom at 389oC goes __0.444______X faster than one at 3089oC.
3. Molecular velocities vs. molecular mass. At the same temperature, same K.E., light molecules go faster.
Velocity is inversely proportional to the SQUARE ROOT of the molecular weights (Graham’s Law).
“lighter is faster”;
V1
m2

V2
m1
a. An H2 molecule, weighing 2.0 g/mol, at 300.K has ___1.00__X as much K.E. as an O2 molecule, weight
32g/mol at 300.K. For this to happen, the 16 times lighter H2 molecule has to be going ___4.00___X as
fast as the O2. b. A molecule that weighs 1/9 as much as another, at the same temperature must be
going ___3__X faster. c. An SO2 molecule (64g/mol) goes ___0.71____X as fast as an O2 molecule at the
same temperature.
d. At a temperature at which O2 molecules go 335 m/sec, H2O molecules will go ___447______m/sec.
4. Combined mass and temperature variations with velocity;
a. O2 molecules at 1200.K go __0.612__X as fast as He molecules at 400.K
b. H2 molecules at -13oC go ___1.00____ X as fast as CH4 molecules at 1786oC.
c. UF6 molecules at 1066oC go __1.37___ X as fast as SF6 molecules at 25oC
V1
m2T1

V2
m1T2