Measuring gases Unit 2 Chem

Particle model

gas - low density, fills space, compressed easily, mix rapidly

liquid - high density, adopts shape of container, incompressible almost, slowly mix

solid - high density, fixed rigid shape, incompressible almost, no mix

Kinetic molecular theory

explains observed properties of gases - gas particles in continuous random motion and collisions between gas particles are fully elastic

Pressure

the force exerted on a unit area of a surface by the particles of a gas as they collide with each other and the walls of the container.

Partial pressure

pressure exerted by a particular gas in a mixture

Temp

amount of heat present in a substance. freeze point water - 0, boil - 100 celsius

Volume

amount of space a substance occupies

What are standard conditions and why do they exist?

SLC at 25C (298K) and pressure of 100kPa. Because volume of gas samples are sensitive to temp and pressue, making the comparison tricky.

Equal volumes of all gases measured at same temp+ pressure contain same no. of particles

If 2 gases have same temperature, pressure and volume → contains same no. of moles

Ideal gas equation

describes behaviour of a hypothetical ideal gas, to then predict behaviour of real gas.

If gases are at SAME pressure and temperature, their MOLAR ratios =

volume ratios. Volume can be used instead of Moles for reactions BUT only for reactants/products in GAS state.