​ ​Chemical​ ​measurements,​ ​conservation​ ​of​ ​mass​ ​and​ ​the quantitative​ ​interpretation​ ​of​ ​chemical​ ​equations

what is the law of conservation of mass

The law of conservation of mass states that no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants.

when may mass not be conserved

if mass increases, its probably because one of the reactants is a gas that’s found in the air

if mass decreases, one of the products may be a mass

if the vessel isn’t enclosed then the gas can escape from the reaction vessel as its formed, its no linger contained within the reaction ​​

Whenever​ ​a​ ​measurement​ ​is​ ​made​ ​there​ ​is​ ​always​ ​some​ ​​*uncertainty*​​ ​about​ ​the result​ ​obtained

what is Mr

relative formula mass

the relative atomic mass of all the atoms in the molecular formula added together

how to calculate % mass of an element in a compound

(Aₙ x number of atoms of that element/ Mₙ of the compound ) x 100