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QUANTITATIVE CHEMISTRY: CONSERVATION OF MASS (THE CONSERVATION OF MASS…
QUANTITATIVE CHEMISTRY: CONSERVATION OF MASS
THE CONSERVATION OF MASS
total mass of the products = total mass of the reactants
mass is conserved because no atoms are lost or made
chemical symbol equations must always be balanced to show the conservation of mass
must be the same number of atoms of each element on both sides of the equation
half-equation: used to show what happens to one reactant in a chemical reaction, with electrons written as e-
ionic equations: used to simplify complicated equations
ionic equations show the species that are involved in the reaction, spectator ions are not included
the term 'species' refers to different atoms, molecules or ions that are involved in a reaction
RELATIVE FORMULA MASS
the sum of the relative atomic masses (Ar) of the atoms in the numbers shown in the formula, does not have a unit
the sum of the relative formula masses of all the products = the sum of the relative formula masses of all the reactants
APPARENT CHANGES IN MASS
some reactions appear to involve a change in mass, this happens when reactions are carried out in a non-closed system and involves a gas that can enter or leave
usually explained because a reactant or product is a gas and its mass has not been take into account
KEY WORDS
conservation of mass
half equation
ionic equation
species
relative formula mass (Mr)
relative atomic mass (Ar)