Conservation of mass

what is conservation of mass

in a chemical reaction the total mass of the products is equal to the total mass of the reactants

why is mass conserved

because no atoms are lost or made

what is half equation

used to show what happens to one reactant in a chemical reactions

example of a half equation of iron atom

Fe(s) → Fe²+(aq) + 2e-

example of a half equation of copper ion

Cu 2+ (aq) + 2e- → Cu (s)

what is an ionic equation

can be used to simplify complicated equations

what are not involved when writing an ionic equation

spectator ions

example of a ionic equation of

AgNO3 (aq) + NaCl (aq) → AgCl (s) + NaNO3 (aq)

Ag2+ (aq) + Cl2- (aq) → AgCl (s)

total mass of products =

total mass of reactants

what is the relative formula mass

Mr of a compound is the sum of the relative atomic masses (Ar) of all the atoms in the numbers shown in the formula

what does the relative formula mass not have

a unit

what is relative atomic mass

(1. isotope mass x 1. isotope abundance) + (2. isotope mass x 2. isotope abundance)

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why do some reactions have a change in mass

this happens when reaction are carried out in a non-closed system, so gasses can enter or leave