Ch. 10Stoichiometry

GCC CHM 130

10.1 Interpreting a Chemical Equation

2 NO (g) + O2 (g) → 2 NO2 (g)2 molecules 1 molecule 2 molecules

10 molecules 5 molecules 10 molecules 2 moles 1 mole 2 mole2

N2 (g) + 3 H2 (g) → 2 NH3 (g)___ molecule(s) ___ molecule(s) ___molecule(s) ____ mole ____ mole ____ mole

So coefficients give us molecule or mole ratios.

10.2 Mole-Mole Ratios___ Fe2O3 (s) + ___ CO (g) __ Fe (s) + ___CO2 (g)

1 mol 3 mol 2 mol 3 mol

1 mol Fe2O3

3 mol COExamples: 3 mol CO

1 mol Fe2O3 3 mol CO2 mol Fe

1.How many moles of iron can be formed from 10.2 moles of carbon monoxide?

2.How many moles of iron(III) oxide are needed to form 17 moles of carbon dioxide?17 mol CO2 ( 1 mol Fe2O3 / 3 mole CO2) = 5.7 mol

Fe2O3

10.2 mol CO ( 2 mol Fe / 3 mole CO) = 6.80 mol Fe

Another Example Balance this reaction:

___ SO2 (g) + ___O2(g) ___SO3(g)

How many moles of SO3 will form if 0.165 moles of oxygen gas react?

How many moles of SO2 are needed to make 0.042 moles of sulfur trioxide?

22

0.165 mol O2 (2 mol SO3 / 1 mol O2) = 0.330 mol SO3

0.042 mol SO3 (2 mol SO2 / 2 mol SO3) = 0.042 mol SO2

10.3-4 Mass – Mass Stoichiometry

Gramsgiven

Molesgiven

Molesfind

Gramsfind

Molar

Mass

Molar

Mass

Mole

Ratio

3 FeO(s) + 2 Al(s) 3 Fe(s) + Al2O3(s)

1.Calculate the mass of iron (II) oxide needed to react completely with 5.55 g of aluminum.

2.Calculate the mass of aluminum oxide produced when 10.25 g of aluminum reacts completely.

1. 5.55 g Al

Al g 26.98

Al mol

Al mol 2

FeO mol 3

FeO mol

FeO g 71.85

= 22.2 g FeO

2. 10.25 g Al

Al g 26.98

Al mol

Al mol 2

OAl mol 1 32

32

32

OAl mol

OAl g 101.96

= 19.37 g Al2O3

3 FeO(s) + 2 Al(s) 3 Fe(s) + Al2O3(s)

10.5-6 Mass – Volume and Volume-Volume problems

Write and balance the reaction of HCl (aq) and solid cobalt. Note cobalt will be +2 as an ion in this example.

How many liters of gas at STP will form if 5.00 grams of cobalt reacts?

If 2.374 L of hydrogen gas formed, how many grams of HCl reacted?

5.00 g Co(mol/58.93)(1 molH2/1molCo)(22.4L/mol) = 1.90 L H2

2.374 L H2 (mol/22.4L)(2 mol HCl/1 mol H2)(36.46 g/mol) = 7.73 g HCl

2 HCl(aq) + Co(s) CoCl2(aq) + H2(g)

HCl gas plus oxygen gas produces chlorine gas

and water vapor.• How many liters of chlorine can be formed if

3.00 liters of oxygen react completely at STP?

4 HCl(g) + O2(g) 2 Cl2(g) + 2 H2O(g)

3.00 L O2 (mol / 22.4 L)(2 mol Cl2 / 1 mol O2)(22.4 L/mol) = 6.00 L Cl2

Skip sections 10.7 - 9

Try at HomeCarbon reacts with oxygen gas to form carbon

monoxide. How many liters of carbon monoxide at STP can be made from

1. 15.0 grams carbon? 2. 20.0 liters of oxygen gas?

Remind me to show answers next time

2 C(s) + O2(g) 2 CO(g)

15.0 g C (mol /12.01g)(2 mol CO/2 mol C)(22.4 L / mol)= 28.0 L CO

20.0 L O2 (mol /22.4L)(2 mol CO /1 mol O2)(22.4 L/mol)= 40.0 L CO

Self Test• Page 288• Try 1-6, 10, 14• Answers in Appendix J