Gases Part 2

Gas Stoichiometry What is the volume of CO 2 produced at 37 0 C and 1.00 atm when 5.60 g of glucose are used up in the reaction: C 6 H 12 O 6 (s) + 6O 2 (g) 6CO 2 (g) + 6H 2 O (l)

Dalton’s Law of Partial Pressures V and T are constant P1P1 P2P2 P total = P 1 + P 2

Consider a case in which two gases, A and B, are in a container of volume V. P A = P B = P T = P A + P B X A = nAnA n A + n B X B = nBnB n A + n B mole fraction (X i ) = nini nTnT

A sample of natural gas contains 8.24 moles of CH 4, moles of C 2 H 6, and moles of C 3 H 8. If the total pressure of the gases is 1.37 atm, what is the partial pressure of propane (C 3 H 8 )? P i = X i P T P T = 1.37 atm

2KClO 3 (s) 2KCl (s) + 3O 2 (g) Bottle full of oxygen gas and water vapor P T = P O + P H O 22

Kinetic Molecular Theory of Gases 1.A gas is composed of molecules that are separated from each other by distances far greater than their own dimensions. The molecules can be considered to be points; that is, they possess mass but have negligible volume. 2.Gas molecules are in constant motion in random directions. Collisions among molecules are perfectly elastic. 3.Gas molecules exert neither attractive nor repulsive forces on one another. 4.The average kinetic energy of the molecules is proportional to the temperature of the gas in Kelvin. Any two gases at the same temperature will have the same average kinetic energy

Kinetic theory of gases and … Compressibility of Gases Boyle’s Law Charles’ Law

Kinetic theory of gases and … Avogadro’s Law Dalton’s Law of Partial Pressures

The distribution of speeds for nitrogen gas molecules at three different temperatures The distribution of speeds of three different gases at the same temperature u rms = 3RT M  Velocity of a Gas

Gas diffusion is the gradual mixing of molecules of one gas with molecules of another by virtue of their kinetic properties. NH 3 17 g/mol HCl 36 g/mol NH 4 Cl

GAS DIFFUSION AND EFFUSION diffusion is the gradual mixing of molecules of different gases.diffusion is the gradual mixing of molecules of different gases. effusion is the movement of molecules through a small hole into an empty container.effusion is the movement of molecules through a small hole into an empty container.

GAS DIFFUSION AND EFFUSION Graham’s law governs effusion and diffusion of gas molecules. Graham’s law governs effusion and diffusion of gas molecules. KE=1/2 mv 2 Thomas Graham, Professor in Glasgow and London. Rate of effusion is inversely proportional to its molar mass.

GAS DIFFUSION AND EFFUSION Molecules effuse thru holes in a rubber balloon at a rate ( moles/time) that is proportional to Tproportional to T inversely proportional to M.inversely proportional to M. Therefore, He effuses more rapidly than O 2 at same T. He

Graham’s Law Problem 1 1 mole of oxygen gas and 2 moles of ammonia are placed in a container and allowed to react at 850 degrees Celsius according to the equation: 4 NH 3 (g) + 5 O 2 (g) --> 4 NO(g) + 6 H 2 O(g) Using Graham's Law, what is the ratio of the effusion rates of NH 3 (g) to O 2 (g)?

Graham’s Law Problem 2 What is the rate of effusion for H 2 if L of CO 2 takes 5.00 sec to effuse out of a container?

Graham’s Law Problem 3 What is the molar mass of gas X if it effuses times as rapidly as N 2 (g)?