Molecular Composition of Gases The Ideal Gas Law.
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Transcript of Molecular Composition of Gases The Ideal Gas Law.
Molecular Composition of Gases
The Ideal Gas Law
Objectives:1. State the ideal gas equation.
2. Derive the ideal gas constant and state its units.
3. Use the ideal gas equation to calculate the amount of gas at any condition of temperature and pressure.
4. Use the ideal gas equation to calculate the molar mass of a gas given its density.
5. Reduce the ideal gas law to Boyle’s, Charles’, Gay-Lussac’s, or Avogadro’s Law.
The Ideal Gas Law
•Mathematical relationship between pressure, volume, temperature, and the number of moles of gas.
Ideal Gas LawCalculate the value of R for 1 mole of gas at STP.
• The value of “R” depends on the units used for P, V, and T.
• The ideal gas law can be reduced to any of the previously studied gas laws when certain variables are held constant.
Kmol
atmL
Kmole
Latm
*
*0821.0
)273)(1(
)4.22)(1(
Sample Problems1. A 2.07 L cylinder contains 2.88 mol of helium gas at
22oC. What is the pressure in atmospheres of the gas in the cylinder?
2. A tank of hydrogen gas has a volume of 22.9 L and holds 14.0 mol of the gas at 12oC. What is the reading on the pressure gauge in atmospheres?
3. A reaction yields 0.00856 mol of O2 gas. What volume will this occupy if it is collected at 43oC and 0.926 atm pressure?
4. What mass of ethene gas, C2H4 is contained in a 15.0 L tank that has a pressure of 4.40 atm at a temperature of 305 K?
Ideal Gas Law and Molar Mass
A chemist determines the mass of a sample of gas to be 3.17 g. Its volume is 942 mL at a temperature of 14oC and a pressure of 1.09 atm. What is the molar mass of the gas.
)27314)(0821.0(1000
194209.1
C
Kmol
atomLn
mL
LmLatm o
molesn 0436.0
molg
mol
g
moles
massM 7.72
0436.0
17.3
Ideal Gas Law and Molar Mass
massMolar
massnSince ""
....orRTM
mPV
PV
mRTM
Ideal Gas Law and Density
Knowing that density is mass/volume, what is the density of a sample of ammonia, if the pressure is 0.928 atm and the temperature is 63.0oC?
Lmol
CKmol
atmL
atm
RT
P
V
n
o
0336.0
2730.630821.0
928.0
Lg
mol
gL
mol 572.01
0305.17)0336.0(
Ideal Gas Law and Density
P
DRT
PV
mRTM
RT
MPDor ...