A mixture of sodium chloride and sodium sulphate is known to contain 0.5 mols of sodium ions and 0.2 mols of chloride ions. How many moles of sulphate ions are present?

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !

we need the questions , i may then you.

you need to stop taking that class