Question

how many grams of Al2O3 be obtained if 13.5 g of aluminum completely reacts with oxygen as
4Al+3O2---->2Al2O3
Molar mass of Al is 27g/mol.

Answer 1

4Al+3O2---->2Al2O3

mols Al = grams Al/atomic mass Al.
Using the coefficients in the balanced equation, convert mols Al to mols Al2O3. You can see that 2 mol Al2O3 are formed for every 4 mols Al initially.
Then convert mols Al2O3 to grams. g = mols x molar mass = ?
Post your wor if you get stuck

Answer 2

n=given mass/reaction mass=13.6/27=1/2
Now.,
n=given mole/reaction mole(Al2O3)=1/2/2=1/4
Now.,
n=mass/molar mass(Al2O3)
mass=1/4*102=25.50grams

Answer 3

4Al +3O2-------------> 2Al2O3
4Al----------->2Al2O3
1Al---------> 2/4 Al2O4
First convert grams to moles
Moles of aluminum = 13.5/27 =0.5
Now we have moles
0.5 moles of Al = 0.5 ×2/ 4 = p

Answer 4

4Al +3O2-------------> 2Al2O3
4Al----------->2Al2O3
1Al---------> 2/4 Al2O4
First convert grams to moles
Moles of aluminum = 13.5/27 =0.5
Now we have moles
0.5 moles of Al = 0.5 ×2/ 4 = 1/4
So we have moles of Al2O3 now but in question they asked us in grams. So we have to convert it to grams
Grams = moles x molar mass of Al2O3
Grams = 1/4 × 102 = 25.5