20.2 The ideal gas law

What is pressure in a gas caused by?

collisions of gas molecules with the walls of their container. These collisions exert force over an area, resulting in pressure.

Brownian motion

the random movement of particles suspended in a fluid, resulting from collisions with the fast-moving molecules of the fluid.

Avogadro’s hypothesis on gas moles

equal volumes of gases at the same temperature and pressure contain equal numbers of molecules

Symbol for Avogadro constant

N_A

What is Avogadro’s constant defined as?

number of atoms in 12g of C-12

Value of N_A

6.023 × 10²³

One atomic unit (u) is ________ mass of a C-12 atom

1/12

mole

the amount of substance that contains Avogadro's number of entities (atoms, molecules, etc.).

molarity

the number of moles in a certain quantity of a substance

molar mass

the mass of one mole of a substance

Convert from u to kg

x 1.661 × 10^-27

Equation for moles in a substance

M_s/ M

M_s= mass

M= molar mass

number of molecules in a substance

N_AM_s/ M

Ideal gas

• Obeys Boyle’s Law at any temperature and pressure

• has molecules with negligible volume

• cannot be liquefied

Combined gas equation

pV/ T= constant

What condition is needed for ideal gas equation?

fixed mass

molar gas constant

R

Ideal gas equation

pV=nRT

Ideal gas equation using Boltzmann constant

pV= NkT

Boltzmann constant

the molar gas constant divided by the Avogadro number