Solution Stoichiometry (Part Two)

Example 1:

250 mL of .300M chromium (II) fluoride reacts with excess zinc. How many grams of chromium are produced?

CrF2  +  Zn  -->  ZnF2  +  Cr

0.250L  x  .300 mol  x 1  x  52.0g  =    3.9 g
                    L            1       mol

- How many moles of ZnF2 are produced?
.250L  x .300 mol  x  1  =    0.075 mol      
                    L            1

Determine [ZnF2]  0.075 mol   x  1      =     0.3 M
                                                  0.250L

Example 2:
A beaker contains 150 mL of 2.5 M HBr. Extra cadmium is added to the beaker.
Determine how many litres of hydrogen gas should be produced at STP.

HBr  +  Cd   -->   H2   +   CdBr2

0.150 L  x  2.5 mol  x  1   x  22.4 L  =   4.2 L
                       L           2        mol
- If 2.50 L of hydrogen gas is actually produced what is the % yield?
                3.5 L  x  100  =  83%
                4.2 L

Example 3:
A 3.00g piece of Iron(II) is added to a beaker containing 100mL of 0.750M of AgNO3. Determine the LR.

0.750mol x 0.100L x 1 x 55.8g = 2.09g of Fe             LR = AgNO3
                                 2     mol

-How many grams of Ag(s) is produced?

0.750mol x 0.100L x 2 x 107.9g = 8.1 g
      L             mol      2      mol

 A video for extra help in Solution Stoichiometry.

 -Ben Suratos