1. Moles to Grams
If you are given moles but the answer must be in grams, you have a mole to mass problem.
Calculate moles just like mole to mole calculations
Use flow chart to change moles to grams (x MM)

2. If you are given moles but the answer must be in grams, you have a mole to mass problem.
Calculate moles just like mole to mole calculations
Use flow chart to change moles to grams (x MM)
How many grams of aluminum are needed to fully react with three moles of O2?
? mol 3 mol
4Al + 3O2  2Al2O3
3x =12
x = 4 mol Al
4 x 27 = 108 g Al

3. How many grams of O2 would be needed to fully react with 12 moles of aluminum?
12 mol ? mol
4Al + 3O2  2Al2O3
4x =12 (3)
4x = 36
x = 9 mol of O2
9 x (16x2) = 288 g of O2

4. How many grams of aluminum are needed to produce 204 grams of Al2O3?
Change 204 grams of Al2O3 to moles (flow chart)
Molar mass of Al2O3 = 2 (27) + 3 (16) = 102
204 / 102 = 2 moles of Al2O3
? mol mol
4Al + 3O2  2Al2O3
2x =2 (4)
2x = 8
x = 4 moles of Al
4 x (27) = 108 g of Al
Now change moles to grams using the flow chart