What is the molar mass of aluminum sulfate?

The molar mass of aluminium sulfate is 342.2 g/mol.
Aluminium sulfate is an with the formula ##Al_2(SO_4)_3##.
It is formed when 2 aluminium cations, ##Al^(3+)##, bond to 3 sulfate anions, ##SO_4^(2-)##.
To get the molar mass of the compound you need to add the molar masses of all the atoms that form the aluminium sulfate formula unit.
This means that you have
two atoms of aluminium – ##2 * “27.0 g/mol”##
three atom of sulfur – ##3 * “32.07 g/mol”##
twelve atoms of oxygen – ##12 * “16.0 g/mol”##
The molar mass of the compound will thus be
##M_M = color(green)(“342.2 g/mol”)##