1. Stoichiometry

2. Definitions
Stoichiometry - deals with mole, mass and volume relationships in chemical reactions
Limiting reactant - controls the amount of product formed
There is no more at the end of the reaction

3. What are we going to do?
From the balanced equation, we can predict the amount of product if given the amount of reactant
From the balanced equation, we can predict the amount of reactant needed if given the desired amount of product

4. What do we need to know?
Mole Ratio – will help convert moles of one compound in a balanced chemical equation into moles of another compound.
Example: Reaction between magnesium and oxygen to form magnesium oxide. ( fireworks)
2 Mg O2  MgO
Mole Ratios:
2 mole : 1 mole : mole

5. Why is this important?
Stoichiometry is used in chemical engineering in order to understand/predict chemical reactions.
Production of items include: soap, tires, fertilizer, gasoline, deodorant, and chocolate bars
Real-life applications in chemical engineering as well as research
Therefore, stoichiometry is one of the most important and fundamental topics in chemistry.

6. Mole to Mole Stoichiometry

7. Mole – Mole Stoichiometry…
Write the balanced equation
Determine which is the starting chemical (A) and which is chemical we want to end up with (B)
Use coefficients of balanced equation to convert moles of chemical A to moles of chemical B
Mole ratio!

8. Some Practice **Remember, UNITS FIRST**
How many moles of water can be obtained from the reaction of 4 moles of O2?
2 H O2 → H2O
4 mol O2 1 x
2 mol H2O
1 mol O2
= 8 mol H2O
Mole Ratio

9. Practice…
In order to produce 15 moles of water, how many moles of oxygen must be reacted?
2 H O2 → H2O

10. Homework – Worksheet #1
Chemical Reactions – add to HW before you leave!
__ Fe + __ O2  __ Fe2O3
__ N2 + __ H2  __ NH3
__ H2 + __ O2  __ H2O
(and 5) __ Mg + __ HCl  __ H2 + __ MgCl2
(and 7) __ H2SO4 + __ NaOH  __ H2O + __ Na2SO4

11. Gram <-> Mole Stoichiometry
Allows you to calculate the mass of product produced or the mass of reactant needed.

12. How do we do this? Write the balanced equation Steps :
Determine which is the starting chemical (A) and which is chemical we want to end up with (B)
Steps :
Convert gA to molA
Use GFW
Convert molA to molB
Use stoichiometry rules
Convert molB to gB

13. Visualizing it a different way
Moles of “A”
Mole Ratio
Moles of “B”
GFW
GFW
Grams of “A”
Grams of “B”

14. Mass-Mass Calculations *Remember, UNITS FIRST!!*
How many grams of SnF2 can be produced from the reaction of g of HF with Sn?
Sn HF → SnF H2
30.00 g HF 1
1 mole HF
20.01 g HF x
1 molSnF2
2 mol HF x
g SnF2
1 mol SnF2 x
GFW HF
Mole Ratio
Answer = g SnF2
GFWSnF2

15. Let’s do some practice…
The combustion of a sample of butane, C4H10 (lighter fluid), produced 2.46 grams of water.
2 C4H O > 8 CO H2O
How many grams of butane were used?

16. Some more practice…
Iodine chloride, ICl, can be made by the following reaction between iodine, I2, potassium iodate, KIO3, and hydrochloric acid I2   +   KIO3  +  6 HCl  ->   5 ICl  +  KCl  +  3 H2O
Calculate how many grams of iodine are needed to prepare 10.3 grams of ICl by this reaction.

17. Stoichiometry with grams, moles and liters…

18. How do we do this? Putting all the steps together….
Write the balanced equation
Determine which is the starting chemical (A) and which is chemical we want to end up with (B)
Steps :
Convert LA/gA (whichever is given) to molA
Use GFW if given grams
Convert molA to molB
Use stoichiometry rules
Convert molB to gB/LB
Use GFW if asking for grams

19. Looking at it another way
Moles of “A”
Mole Ratio
Moles of “B”
GFW or Liter Conv.
GFW or Liter Conv
Liters or Grams of “A”
Liters or Grams of “B”

20. Practice Problem
Nickel metal reacts with silver nitrate solution according to the following balanced equation.
             Ni + 2 AgNO >  2 Ag + Ni(NO3)2
If 21.4 L of silver nitrate solution reacts with an excess of nickel metal, calculate the mass of silver produced.