Question

I really really need the steps to do this. Not really the answer but at least the steps. It’s due first thing tomorrow then I got a big test on it. Plz plz need help with these.

1) 45.7 grams of calcium chloride reacts with an excess of aluminum oxide. How many grams of aluminum chloride will be produced?

2) 25.6 grams of sodium reacts with an excess of oxygen. How many grams of sodium oxide will be produced?

Answer 1

Problem 1.
1) Grams to mole, for this we need to know molar mass of a substance.
45.7 grams of calcium chloride 
calcium chloride is CaCl2
Molar mass (CaCl2) = 40.1 +2*35.5 = 111.1 g/mol

45.7 gram* 1 mol/111.1 g =(45.7/111.1) mol CaCl2

2) reaction
                                3CaCl2 +Al2O3 -----> 3CaO +2AlCl3
from reaction         3 mol                                          2 mol
from the problem 45.7/111.1 mol                          x mol
We have a proportion, so
x= (45.7/111.1)mol*2/3 mol AlCl3

3) Find mass of (45.7/111.1)*2/3 mol AlCl3

Molar mass (AlCl3) = 27.0 +3*35.5= 133.5 g/ mol
((45.7/111.1)*2/3 )*133.5g/1mol= 36.6 g  AlCl3

Problem 2. 
This problem can be solved the way like the first one.
But both problems can be solved different way.

Second way to solve these problems.
M(Na)=23.0 g/mol,
M(Na2O)= 2*23.0 +16.0= 62.0 g/mol


                                          4Na  + O2 ----->                2Na2O
 moles from reaction     4mol                                        2 mol
masses from reaction  4mol*23.0g/1mol                     2mol*62.0 g/mol
                                           92 g                                          124 g

masses from the problem 25.6 g                                     x g

Now, we can write a proportion:
92 g Na        produce      124 g Na2O
25.6 g Na    produce        x g Na2O

92/25.6 = 124/x

x=25.6*124/92=   35.5   g Na2O