Amount of a substance

pV = nRT

• gases made up of molecules which are in constant random motion in straight lines • molecules behave as rigid spheres • pressure is due to collisions between molecules and container walls • all collisions are perfectly elastic (no energy lost) • temperature of the gas is directly proportional to the kinetic energy of the particles

• there are no (entirely negligible) forces between molecules • the volume occupied by the molecules is negligible compared to the volume of the container

the proportion of the total mass of the products that is in the desired product

compares the amount produced to the amount that should have been produced

quantity with units mol, used as a means of comparing any species such as atoms, ion, molecules

6.03 x 10^23

water molecules bonded into the crystalline structure of a compound

solution of known conc

vol (dm3) / 24dm3

• using ideal gas • add small sample of the volatile liquid to a syringe through a needle • weigh syringe • inject into gas syringe through self-sealing rubber cap • reweigh small syringe to find mass of liquid • place gas syringe in boiling water bath at 100 degrees • liquid vaporises and pressure recorded • use ideal gas to calc unknowns

sum of molar mass of desired products / sum of all molar mass of products

mass of an isotope relative to the mass of a 1/12 of carbon12

• weigh crucible • add sample of salt • reweigh • use pipe-clay triangle to support crucible on tripod • heat gently with Bunsen for 1 min • heat strongly for 3 more mins • remove and let cool • reweigh • find moles of anhydrous salt formed • find moles water lost • find ratio of moles

1) all water is lost - solution: heat until constant mass 2) no further decomposition has occurred - hard to tell as no colour change