Chapter 10

Chemical Reactions

Types of Chemical ReactionsTypes of Chemical Reactions

1) Oxidation-Reduction (Redox)

2) Combination

3) Decomposition

4) Replacement

5) Ion Exchange

2 KI + Pb(NO3)2 → PbI2 ↓ + 2 KNO3

PbI2 (s)

Pg 251KI(aq)

Ion Exchange Reaction – ions of one compound

react with ions of another compound to form:

(1) a solid (precipitate) or

FeCl3 + 3 NaOH → Fe(OH)3 + 3 NaCl

(2) a gas or (3) water

CaCO3 + 2 HCl → CaCl2 + CO2 ↑ + H2O

By definition: 1 atom 12C “weighs” 12 u

On this scale

1H = 1.008 u

16O = 16.00 u

Atomic mass ≡ mass of an atom in atomic mass units (u)

Micro Worldatoms & molecules

Macro World(grams)

Natural lithium is:

7.42% 6Li (6.015 u)

92.58% 7Li (7.016 u)

(7.42 · 6.015) + (92.58 · 7.016)100 = 6.941 u

Average atomic mass of lithium:

Average atomic mass (6.941)

mole - the amount of a substance that contains as many particles as there

are atoms in exactly 12.00 grams of 12C

1 mol = NA = 6.02 x 1023

Avogadro’s number (NA)

UNITSUNITS

Molar mass - the mass of 1 mole of in gramseggsshoes

marblesatoms

1 mole 12C atoms = 6.022 x 1023 atoms = 12.00 g

1 12C atom = 12.00 u

1 mole 12C atoms = 12.00 g 12C

1 mole lithium atoms = 6.941 g of Li

For any element

atomic mass (u) = molar mass (grams)

1010

One Mole of:

C S

Cu Fe

Hg

1111

Molecular mass (or molecular weight) - the sum ofthe atomic masses (in u) in a molecule.

SO2

1S 32.07 u

2O + 2 x 16.00 u SO2 64.07 u

For any molecule

molecular mass (u) = molar mass (grams)

1 molecule SO2 = 64.07 u

1 mole SO2 = 64.07 g SO2

12

Fig 10.16 The moleconcept for:(A)Elements:

(B) Compounds:

(C) Molecularsubstances:

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