C3- Quantitative Chemistry

chemistry 3

what does Mr stand for

relative formula mass

how do you calculate % mass of an element in a compound

= (hrelative atomic mass (Ar) x number of atoms of that element / mr of the compound) x 100

how much is a mole

6.02 × 10^23

formula to find number of moles

mass in g of an element or compound/ relative formula mass

what is the conservation of mass rule

during a chemical reaction no atoms are destroyed or created - therefore no mass is lost or gained

give 2 reasons why the mass may have changed during a chemical reaction

1. one of the reactants is gas that’s found in the air and after the reaction the gas forms part of the reaction

2. gas is produced during the reaction

when do reactions stop

when one reactant is used up

what is a limiting reactant

the reactant that’s used up

equation for concentration

concentration = mass of solute / volume of solvent