Chapter 5 Gases
Chapter 5 Gases
WHY?
Sketch of ModernBalloons
WHY?
Mathematics
V/T = constant
1.00PSI
8.00PSI
8.00
WHY?
PSI
Mathematics
PV = constant
Mathematics
V/n = constant(n = moles)
Moles
273K ATM
1.00
804K ATM
9.79
(atm)
Mathematics
P/T= constant
MathematicsSummary
V/n = constant
V/T = constant
P/T = constant
PV = constant
MathematicsSummary
V/nT = constant
P/T = constant
PV/nT = constant
MathematicsSummary
PV/nT = constant
PV = nTconstantconstant = R
PV = nRT Ideal Gas Law
Conditions of UsePV = nRT Ideal Gas Law
P units must be atm’s
V units must be liters
T must be in Kelvin
Gas Law ResourcesPressures equivalent to the standard 1.00 ATM
28.3 ft. H2O
29.92 in. Hg
76.0 cm Hg
760.0 mm Hg
760.0 torr
14.7 psi.
1.013 bar
1.013 x 105 Pa
101.3 kPa
(1 Pa = 1 Nt/M2)
PracticeFill out the following chart.
mm Hg. atm. kPa. bar
1215 .
0.714 .
143 .
0.904 .
Gas Law ResourcesTemperature - must be absolute - never negative
Temperature must be in Kelvin
K = oC + 273
PracticeCalculate the volume of 1.0 mole of a gas at Standard Temperature and Pressure.
PracticeFill out the following chart for C4H10
Press. Vol. Temp. Moles Grams
1.75 L 19 oC 1.66 .
0.895 atm 6.0 oC 14.0 .
433 mm Hg 92.4 mL 0.395 .
1.74 bar 8.66 L 310 K .
Experiment
Experiment
Experiment
4 Fe + 3 O2 → 2 Fe2O3
Fe + N2 → NR
Interpretation
•Air contains both N2 and O2
•Each gas has its own independent pressure.
•“The sum of all individual gas pressures in a gas mixture is equal to the total pressure” DALTON
•Dalton’s Law of Partial Pressures
(go to video)
KMT•Kinetic Molecular Theory of gases
Gases consist of very tiny particles in continuous random motion.
Particle collisions are elastic(no energy lost).
Particle volume is negligible.
Particle interaction is negligible.
molecular speed causes both pressure and volume of gases
Graham’s Law Often called Grahams’ Law of Diffusion - in error Diffusion - movement of gas down an open tube complex and influenced by many factors.Effusion - movement of gas through small holes.Graham’s Law of Effusion of Gases“At a given temperature and pressure, gaseous effusion rate in moles per time unit, is inversely proportional to the square root of the molar mass of the gases”.
effusion rate of B = √effusion rate of A √
Ideal vs Real Review KMT. Obvious non-realities.
Some gas molecules are NOT tiny.
Many gas collisions DO lose energy
Gas molecules HAVE a noticeable volume
Some molecules have SIGNIFICANT interaction.