Solutions and reactions..Chemistry

Question

A solution containing 1.63 grams BaCl2 is added to a solution containing 2.40 grams of Na2CrO4 and reacts according the equation BaCl2 Na2CrO4 ® BaCrO4 2 NaCl

How many grams of BaCrO4 can be formed?

a. 1.98 grams

b. 3.75 grams

c. 4.03 grams

d. 6.23 grams

Answer 1

a. 1.98 grams

First convert the reactants to moles:

1.63 g BaCl2 x 1 mole/208.23 g = 0.00783 moles BaCl2

2.40 g Na2CrO4 x 1 mole/161.97 g = 0.0148 moles Na2CrO4

Now look at the stoichiometry: 1 mole of BaCl2 reacts with 1 mole of Na2CrO4 to make 1 mole of BaCrO4 and 2 moles of NaCl. Since you only have 0.00783 moles BaCl2 and 0.0148 moles Na2CrO4, you know that BaCl2 is the limiting reactant. If you only have 0.00783 moles of BaCl2, you can only make 0.00783 moles of the product BaCrO4.(The problem does not ask you to worry about how much NaCl you can make, so don't worry about it.) In other words, the limiting reactant, BaCl2, and the product BaCrO4 are in a 1-to-1 relationship. You can't make more moles of the product BaCrO4 than you have of the limiting reactant, BaCl2.

Now all you need to do is convert moles of BaCrO4 to grams:

0.00783 moles x 253.37 grams/mole = 1.98 grams BaCrO4

So there  you are -- 1.98 grams!

Hope this helps.

Answer 2

b)3.75 grams