CP Chemistry

Unit 8 StoichiometryChapter 9

Unit 6b Stoichiometry Standards

3.2.10 B Apply process knowledge and organize scientific and technological phenomena in varied ways.

3.2.10 C Apply the elements of scientific inquiry to solve problems.

3.4.10 A Explain concepts about the structure and properties of matter.

Chapter Themes The Power of a Balanced Equation Stoichiometry Limiting Reactants Yield (actual / theoretical / percent) Day One Assignment Day Two … Class Information Day Two Assignment

The Power of a Balanced Equation Discover that a balanced equation provides much

information …

2H2O 2H2 + O2

2 molecules of water = 2 molecules of hydrogen plus 1 molecule of oxygen

2 moles of water = 2 moles of hydrogen plus 1 mole of oxygen

2 dozen molecules of water = 2 dozen molecules of hydrogen plus 1 dozen molecules of oxygen

The decomposition of water yields twice as much hydrogen as oxygen.

Stoichiometry Definition:

The process of using a chemical equation to calculate the relative masses of reactants and products involved in a reaction.

In ordinary English:If you know one mass, you can calculate any other mass!

Stoichiometry We do this everyday … Recipe …

Betty Crocker Cake Mix … Double Chocolate Delight

1 egg1/3 cup oil

+ 8 X 12 greased cake pan1 Double Chocolate Delight Cake

1 egg + 1/3 cup oil 1 D.C.D.C.

Stoichiometry We do this everyday … Recipe … Milage …

11 gallons gas + 1 ’97 Neon 382 miles driven

11 gallons gas + 1 Neon 382 miles

Limiting Reactants Consider sandwiches …

1 sandwich = 2 pieces of bread1 piece cheese3 slices of meat

How many sandwiches can you make with 7 pieces of bread; 5 pieces of cheese; and 25 slices of meat?

Yield (actual / theoretical / percent) Back to the ’97 Neon …

- Do I always get 382 miles / 11 gallons?

What do you think these words mean? Actual yield … Theoretical yield … Percent yield …

Day One Assignmentp. 282: 3a&d; 4b&d; 10b&d 3a 2NO + O2 2NO2

2 molecules NO + 1 molecule O2 yields 2 molecules NO2

2 moles NO + 1 mole O2 yields 2 moles NO2

3d C2H6 + Cl2 C2H5Cl + HCl1 molecule C2H6 + 1 molecule Cl2 yields 1 molecule C2H5Cl + 1 molecule HCl1 mole C2H6 + 1 mole Cl2 yields 1 mole C2H5Cl + 1 mole HCl

Day One Assignmentp. 282: 3a&d; 4b&d; 10b&d 4b B2O3 + 3CaF2 2BF3 + 3CaO

1 molecule B2O3 + 3 molecule CaF2 yields 2 molecules BF3 + 3 molecules CaO1 mole B2O3 + 3 moles CaF2 yields 2 moles BF3 + 3 moles CaO

4d C6H6 + 3H2 C6H12

1 molecule C6H6 + 3 molecules hydrogen gas yields 1 molecule C6H12

1 mole C6H6 + 3 moles hydrogen gas yields 1 mole C6H12

Day One Assignmentp. 282: 3a&d; 4b&d; 10b&d 10b SeO2 + 2H2Se 3Se + 2H2O

0.625 mole H2O X 3 mole Se/2 mole H2O = 0.938 mole Se

10d Fe2O3 + 2Al 2Fe + Al2O3

0.625 mole Al2O3 X 2 moles Fe/1 mole Al2O3 = 1.25 mole Fe

Day Two … Class Information The Meaning of a Balanced Chemical Equation

2H2O 2H2 + O2

2 molecules of water = 2 molecules of hydrogen plus 1 molecule of oxygen

2 moles of water = 2 moles of hydrogen plus 1 mole of oxygen

2 dozen molecules of water = 2 dozen molecules of hydrogen plus 1 dozen molecules of oxygen

The decomposition of water yields twice as much hydrogen as oxygen … MOLE RATIOs

Day Two … Class Information

2H2O 2H2 + O2

2 moles of H2O = 2 moles H2 + 1 mole O2

6 moles of H2O = __ moles H2 + __ moles O2

6 moles of H2O = 6 moles H2 + 3 moles O2

½ mole H2O = __ mole H2 + __ mole O2

½ mole H2O = ½ mole H2 + ¼ mole O2

Day Two … Class Information

2NH3 N2 + 3H2

2 moles NH3 1 moles N2 + 3 moles H2

4 moles NH3 __ moles N2 + __ moles H2

4 moles NH3 (1 mole N2 / 2 moles NH3) = 2 moles N2

4 moles NH3 (3 mole H / 2 moles NH3) = 6 mole H2

Day Two … Class Information

3MnO2 + 4Al 3Mn + 2Al2O3

3 moles MnO2 + 4 moles Al 3 moles Mn + 2 moles Al2O3

0.685 moles Al = ______ moles Mn

0.685 moles Al (3 moles Mn / 4 moles Al) = 0.514 moles Mn

Day Two Assignmentp. 282: 8b&d; 13d&g; 14b&d 8b Cl2 + 2KI 2KCl + I2

0.125 mole KI X 2 mole KCl/2 mole KI = 0.125 mole KCl

0.125 mole KI X 1 mole I2 /2 mole KI = 0.0625 mole I2

8d CaC2 + 2H2O Ca(OH)2 + C2H2

0.125 mole CaC2 X 1 mole Ca(OH)2/1 mole CaC2 = 0.125 mole Ca(OH)2

0.125 mole CaC2 X 1 mole C2H2 / 1 mole CaC2 = 0.125 mole C2H2

Day Two Assignmentp. 282: 8b&d; 13d&g; 14b&d 13d molar mass of SO2 = 64.07 g/mole

(5.23 kg SO2)(1000g/1 kg)(1 mole/64.07g) = 81.6 mole SO2

13g molar mass of LiOH = 23.95 g/mole(6.91 X 103 g LiOH)(1 mole/23.95 g) = 288.5 = 289 mole

LiOH

Day Two Assignmentp. 282: 8b&d; 13d&g; 14b&d 14b molar mass of He = 4.003 g/mole

(2.75 mole He)(4.003 g/1 mole He) = 11.0 g He

14d molar mass of CO2 = 44.01 g/mole(7.21 X 10-3 mole CO2)(44.01 g/1 mole CO2) = 0.317 g

CO2