January 25,2010

Today in class, Mr. Doktor went over any questions from the last homework.
MASS TO MASS & OTHER CONVERSIONS
Example.
Lead(IV) nitrate reacts w/5.0 g of potassium iodide. How many grams of lead(IV) nitrate are required for a complete reaction.
Pb(NO3)4 + 4KI -> PbI4 + 4KNO3

5.0g x 1 mole/ 166g x 1 mole/4 KI x 4 55.29/1 mole Pb(NO3)4 = 35g

2)How many grams of O2 are produced from the decomposition of 3.0g of potassium chlorate?
2KClO3 -> 2KCl + 3O2

3.0g x 1mole/122.6g x 3 mol O2/ 2 mole KClO3 x 33g/ 1 mole O2 = 1.2 g

3) If a 100mL solution of 2.0M(mol/L) H2SO4 is neutralized by solution hydroxide. What mass water is produced.
H2S04 + 2NaOH -> 2HoH + Na2SO4

0.100L x 2.0 mole/ L = .200 mole

.200mole H2SO4 x 2 mole HOH/ 1 mole H2SO4 x 18.0g/1mole = 7.2 g

% yield

• Theorteical yield of a reaction is the quanitity of producits expected
• The amount produced in an experiement is teh actual yield

The percent yield is:
% yield = actual/theoretical x 100

Example
The production of urea CO(NH2)2 is given by
NH3 + CO2 -> CO(NH2)2 + H20

47.7 g of urea are produced, determine
a)Theoretical yield if 1 mol of CO2 reacts
1.0 mole CO2 x 1 CO(NH2)2/1 CO2 x 60.1g/1mole = 60.1g
b) actual yield
47.7g
c)percent yield
47.7g/60.1g x 100 =

HOMEWORK

Gravimetric stoichiometry # 15-20 & extra stoichiometry problems worksheet