1 Chapter 4 Recycling and Chemical Mathematics. 2 Nature’s Recycling – The carbon cycle.

1

Chapter 4Chapter 4

Recycling and Chemical MathematicsRecycling and Chemical Mathematics

2

Nature’s Recycling –The carbon cycle

3

Chemical Equations

Chemical reaction: the reorganization of the atoms in one or more substances to form a different substance(s).

A chemical equation for respiration:

C6H12O6(s) + 6O2(g) → 6CO2(g) + 6H2O(l)

What does this equation mean?What does this equation mean?

4

What does this equation mean?What does this equation mean?

C6H12O6(s) + 6O2(g) → 6CO2(g) + 6H2O(l)

“One molecule of glucose solid reacts with six molecules of oxygen gas to give (or produce) six molecules of carbon dioxide gas and six molecules of water.”

5

Accounting for atoms in the process of respiration

6

Example:Example: Recognizing Balanced Equations

Is the following equation balanced?

CaCl2 + 2Na3PO4 → Ca3(PO4)2 + 3NaCl

7

Solution:Solution: Recognizing Balanced Equations

This is the balanced chemical equation.

33CaCl2 + 22Na3PO4 → Ca3(PO4)2 + 66NaCl

8

Producing Aluminum via the Hall-Heroult Process

2Al2O3(l) + 3C(s) → 4Al(l) + 3CO2(g)

9

Example:Example: Atomic Masses

The mass of an atom is the weighted average of its naturally-occurring isotopes.Gallium has 2 isotopes,

60.10% 69Ga (= 68.93 amu) and

39.90% 71Ga (= 70.92 amu).

What is the average atomic massaverage atomic mass of Ga?

10

Solution:Solution: Atomic Masses

60.10% 69Ga (= 68.93 amu) and

39.90% 71Ga (= 70.92 amu).

What is the average atomic massaverage atomic mass of Ga?

(0.6010 x 68.93) + (0.3990 x 70.92) = contribution of 69Ga isotope contribution of 71Ga isotope

69.72 amu69.72 amu

11

Formula Masses

The sum of the atomic masses of all the atoms in the formula.

H2O = 2 x 1.008 + 1 x 16.00 = 18.02 amu hydrogen oxygen

Fe(OH)3 = 1 x 55.847 + 3 x (16.00 + 1.008) = 106.87 amu iron oxygen hydrogen

12

Avogadro’s Number

1 mol of anything = 6.02 x 1023 things 1 mol of C atoms = 6.02 x 1023 C atoms 1 mol of Al atoms = 6.02 x 1023 Al atoms

1 mol of Al2O3 = 6.02 x 1023 Al2O3 formula units 1 mol of frosted flakes =

6.02 x 1023 frosted flakes (Yum!)(Yum!)

13

Conversions: Moles to Grams

How many grams of Al2O3 are in 31.27 moles of Al2O3?

= 3188 g Al= 3188 g Al22OO33

32

3232 O Almol 1

O Alg 101.96 x O Almol 31.27

14

Conversions: Grams to Moles

How many moles of (NH4)2Cr2O7 are in 586.2 grams of (NH4)2Cr2O7?

= 2.326 moles of NH= 2.326 moles of NH44CrCr22OO77

7224

72247224 OCr)(NH g 06252

OCr)(NH mol 1 x OCr)(NH g 586.2

.

15

Using Equations for Stoichiometric Calculations

How many moles of iron can be formed from 2.8 moles of iron(III) oxide, Fe2O3?

Fe2O3 + 2Al → 2Fe + Al2O3

16

Solution:Solution: Using Equations for Stoichiometric Calculations

How many moles of iron can be formed from 2.8 moles of iron(III) oxide, Fe2O3?


= 5.6 moles Fe= 5.6 moles Fe

3232 OFe mol 1

Fe mol 2 x OFe mol 2.8

17


How many grams of Al2O3 can be formed from 1162 grams of Fe2O3?


18




StrategyStrategy

g Fe2O3 → mol Fe2O3 → mol Al2O3 → g Al2O3

19



g Fe2O3 → mol Fe2O3 → mol Al2O3 → g Al2O3

= 741.8 g Al= 741.8 g Al22OO33

32

32

32

32

32

3232 O Almol 1

O Alg 101.96 x

OFe mol 1

O Almol 1 x

OFe g 159.7

OFe mol 1 x OFe g 1162

20


How many grams of CO2 can be formed from 80.7 grams of C6H12O6 in respiration? Assume excess oxygen.

C6H12O6 + 6O2 → 6CO2 + 6H2O

21


How many grams of CO2 can be formed from 80.7 grams of C6H12O6 in respiration? Assume excess oxygen.

C6H12O6 + 6O2 → 6CO2 + 6H2O

StrategyStrategy

g C6H12O6 → mol C6H12O6 → mol CO2 → g CO2

22



g C6H12O6 → mol C6H12O6 → mol CO2 → g CO2

= 118 g CO= 118 g CO22

2

2

6126

2

6126

61266126 CO mol 1

CO g 44.01 x

OHC mol 1

CO mol 6 x

OHC g 180.2

OHC mol 1 x OHC g 80.7

23

Common Polymers and Their Monomers

1 Chapter 4 Recycling and Chemical Mathematics. 2 Nature’s Recycling – The carbon cycle.

Documents

Transcript of 1 Chapter 4 Recycling and Chemical Mathematics. 2 Nature’s Recycling – The carbon cycle.