chapter 7 moles

what is a mole?

number of moles formula (particles)

Aᵣ and Mᵣ

One mole of any substance has a mass equal to its relative atomic mass(for elements) (Aᵣ), relative molecular mass (for molecules) or relative formula mass (for iconic compounds)

This mass is the molar mass (g/mol) of the substance.

average mass is relative to 1/12 the mass of an atom of carbon-12 

Mᵣ of a substance can be calculated by adding together the Aᵣ of all the atoms in its chemical formula

** Molar mass = Aᵣ/Mᵣ -> the only difference is that molar mass has units

number of moles involving Mᵣ/Aᵣ

moles and gaseous volumes

concentration

chemical calculations from equations

** If the given and required is gas to gas then we can use a shortcut

Do not need to do mole ratio, so don’t need to find no. of moles

Just do volume ratio as mole of gas always occupy the same volume

limiting reactants

** The amount of product formed depends on the amount of limiting reactant present (start with limiting reactant on left in mole ratio)

what is left behind is products formed + reactants in excess