I. Stoichiometric

Calculations

I. Stoichiometric

Calculations

Stoichiometry – Ch. 8Stoichiometry – Ch. 8

COOKIE STOICHIOMETRYCOOKIE STOICHIOMETRYCOOKIE STOICHIOMETRYCOOKIE STOICHIOMETRY

I have 5 eggs. How many cookies can I make?

3/4 c. brown sugar1 tsp vanilla extract2 eggs2 c. chocolate chipsMakes 5 dozen cookies.

2 1/4 c. flour1 tsp. baking soda1 tsp. salt1 c. butter3/4 c. sugar

5 eggs 5 doz.

2 eggs= 12.5 dozen cookies

Ratio of eggs to cookies

A. Proportional A. Proportional RelationshipsRelationshipsA. Proportional A. Proportional RelationshipsRelationships

StoichiometryStoichiometry• mass relationships between

substances in a reaction• based on mole ratio

Mole RatioMole Ratio• coefficients in a balanced equation

2 Mg + O2 Mg + O22 2 MgO 2 MgO

B. Stoichiometry StepsB. Stoichiometry StepsB. Stoichiometry StepsB. Stoichiometry Steps

1. Write a balanced equation.2. Identify known & unknown.3. Line up conversion factors.

• Mole ratio - moles moles• Molar mass - moles grams• Molarity - moles liters soln• Molar volume - moles liters gas

Core step in all stoichiometry problems!!

• Mole ratio - moles moles

4. Check answer.

1 mol of a gas=22.4 Lat STP

C. Molar Volume at STPC. Molar Volume at STPC. Molar Volume at STPC. Molar Volume at STP

Standard Temperature & Pressure0°C and 1 atm

D. MolarityD. MolarityD. MolarityD. Molarity

M = moles of solute

Liters of solution

C. Molar Volume at STPC. Molar Volume at STPC. Molar Volume at STPC. Molar Volume at STP

Molar Mass(g/mol)

6.02 1023

particles/mol

MASSIN

GRAMSMOLES

NUMBEROF

PARTICLES

LITERSOF

SOLUTION

Molar Volume (22.4 L/mol)

LITERSOF GASAT STP

Molarity (mol/L)

Bellwork: Bellwork: Bellwork: Bellwork:

NH3 + O2 N2 +H20

Balance the equation above.

Determine the amount of moles for each of the reactants and products when the following are used.

a. 4 moles NH3

b. 4.5 moles O2

D. Stoichiometry D. Stoichiometry ProblemsProblemsD. Stoichiometry D. Stoichiometry ProblemsProblems

How many moles of KClO3 must decompose in order to produce 9 moles of oxygen gas?

9 mol O2 2 mol KClO3

3 mol O2

= 6 mol KClO3

2KClO3 2KCl + 3O2 ? mol 9 mol

How many grams of KClO3 are req’d to

produce 9.00 L of O2 at STP?

9.00 LO2

1 molO2

22.4 L O2

= 32.8 g KClO3

2 molKClO3

3 molO2

122.55g KClO3

1 molKClO3

? g 9.00 L

D. Stoichiometry D. Stoichiometry ProblemsProblemsD. Stoichiometry D. Stoichiometry ProblemsProblems

2KClO3 2KCl + 3O2

D. Stoichiometry D. Stoichiometry ProblemsProblemsD. Stoichiometry D. Stoichiometry ProblemsProblems

How many grams of silver will be formed from 12.0 g copper?

12.0g Cu

1 molCu

63.55g Cu

= 40.7 g Ag

Cu + 2AgNO3 2Ag + Cu(NO3)2

2 molAg

1 molCu

107.87g Ag

1 molAg

12.0 g ? g

63.55g Cu

1 molCu

D. Stoichiometry D. Stoichiometry ProblemsProblemsD. Stoichiometry D. Stoichiometry ProblemsProblems

How many grams of Cu are required to react with 1.5 L of 0.10M AgNO3?

1.5L

.10 molAgNO3

1 L= 4.8 g

Cu

Cu + 2AgNO3 2Ag + Cu(NO3)2

1 molCu

2 molAgNO3

? g 1.5L0.10M