Chapter 9 Notes I Stoichiometry

Stoichiometry Calculations of quantities in chemical reactions This means using balanced equations to calculate quantities of chemicals used in a chemical reaction

A chemical equation is like a recipe; it shows you how much of each “ingredient” is used and how much product you will have in the end.

N 2 + 3H 2 a 2NH 3 How many molecules of N 2 are there?

How many molecules of H 2 are there?

How many molecules of NH 3 are there?

So one molecule of N 2 molecules of H 2 will react with 3 to form 2 molecules of NH 3 .

You could also say that one mole of N 2 react with 3 moles of H 2 will to form 2 moles of NH 3 .

The heart of stoichiometry is using a balanced chemical equation as a conversion factor for dimensional analysis.

Zn + HCl a ZnCl 2 + H 2 For the above reaction, how many moles of zinc chloride can be produced with 0.27 moles of zinc?

Zn +2 HCl a ZnCl 2 + H 2 For the above reaction, how many moles of zinc will react with 1.39 moles of hydrochloric acid?

Why are mole/mole problems impractical in a laboratory setting?

4Fe + 3O 2 a 2Fe 2 O 3 How many grams of iron (III) oxide can be produced with 17.2g Fe?

4Fe + 3O 2 a 2Fe 2 O 3 How many grams of iron will react with 5.25 liters of O 2 (@STP)?

4Fe + 3O 2 a 2Fe 2 O 3 How many molecules of O 2 produce 3.92g Fe 2 O 3 ?

are needed to

Density Remember, a conversion from liters to moles is only valid for gases at STP.

Converting from/to liters (or mL) for liquids or solids involve using density as a conversion factor.

If you have 10.0mL of isopropyl alcohol (C 3 H 7 OH) and burn it, how many liters CO 2 gas are produced @STP? The reaction is combustion.

D = 0.798g/mL

10.0mL (C 3 H 7 OH) D = 0.798g/Ml how many liters CO 2 Find Mass using D=M/V

Write the reaction 2C 3 H 7 OH + 9O 2  6CO 2 + 8H 2 0 7.98g ? L