Question

1.) 22.5 grams of Potassium nitrate react with Sodium Bromide to produce how many grams of
Potassium Bromide?

2.)Scandium (III) Sulfide reacts with solid Aluminum to produce 16.3 grams of Aluminum Sulfide,
how many grams of Scandium (III) Sulfide were used in the reaction?

Answer 1

in both cases, write the equation.
Figure how many moles of the limiting reactant you have
The equation will tell you how many moles or product to expect
convert that back to grams

For #2, just work backwards. The key is to change everything to moles, and make sure the equation is balanced right.