Title: Chapter 4: Types of Chemical Reactions
1Chapter 4 Types of Chemical Reactions
- Goals
- To be able to predict chemical reactivity.
- To know how to synthesize specific compounds.
2Types of Reactions
- Acid-Base proton-transfer
- Oxidation-Reduction electron-transfer
- Precipitation formation of insoluble salts
- Gas Forming
- Organic
- Substitution
- Addition
- Elimination
3Reactions in Aqueous Solution
- Unless mentioned, all reactions studied this and
next week occur in aqueous solution.
4Electrolytes
Strong Electrolytes solute breaks apart to give
ions in solution. NaCl ? Na Cl- Weak
Electrolytes solute partially breaks apart to
give ions. CH3CO2H ? CH3CO2- H
happens less than 5 Nonelectrolytes no ions
formed. CH3CH2OH
5Brønsted-Lowery Acid-Base Definitions
- An acid is a substance that donates a proton (H)
to a base - A base is a substance that accepts a proton (H)
from an acid
6Brønsted-Lowery Definitions
- An acid is a substance that donates a proton (H)
to a base - A base is a substance that accepts a proton (H)
from an acid - Acid-base reactions can be reversiblereactants
? products or products ? reactants
7Brønsted-Lowery Definitions
- An acid is a substance that donates a proton (H)
to a base - A base is a substance that accepts a proton (H)
from an acid - Acid-base reactions can be reversiblereactants
? products or products ? reactants
8Important Acids and Bases
Strong Acids HCl hydrochloric HBr hydrobromic H
I hydroiodic HNO3 nitric H2SO4 sulfuric HClO4
perchloric Weak Acid CH3CO2H acetic Any other
acids are WEAK
Strong Bases LiOH lithium hydroxide NaOH sodium
hydroxide KOH potassium hydroxide Ca(OH)2 c
alcium hydroxide Weak Base NH3 ammonia
9- STRONG acids in water 100 of acid molecules
form ions - HCl(aq) H2O(l) ? H3O(aq) Cl-(aq)
H3O is hydronium ion
10- WEAK acids in water, 5 or less of acid
molecules form ions (acetic, H3PO4, H2CO3)
11Polyprotic Acidsmultiple acidic H atoms
- H2SO4 ? H HSO4-
- HSO4- ? H SO42-
- Not all Hs are acidic
- CH3CO2H
12If H3PO4 reacts as an acid, which of the
following can it not make?
- 1. H4PO4
- 2. H2PO4-
- 3. HPO42-
- 4. PO43-
13If C2O42- reacts in an acid-base reaction, which
of the following can it not make?
- 1. H2C2O4
- 2. HC2O4-
- 3. 2 CO2
14Acid-Base Reactions
- Strong Acid Strong Base
- HCl(aq) NaOH(aq) ? NaCl(aq) H2O(l) acid
base salt water
15Net Ionic Equations
- HCl(aq) NaOH(aq) ? NaCl(aq) H2O(l)
- What really happens
- H(aq) OH-(aq) ? H2O(l)
- Sodium ion and chloride ion are spectator ions
16Reactions involving weak bases
- HCl(aq) NH3(aq) ? NH4(aq) Cl-(aq)
- Net-Ionic Equation
- NH3(aq) H(aq) ? NH4(aq)
17CH3CO2H(aq) NaOH(aq) ?
- 1. CH3CO2H2(aq) NaO(aq)
- 2. CH3CO2-(aq) H2O(l) Na(aq)
- 3. CH4(g) CO2(g) H2O(l)
18HCN(aq) NH3(aq) ?
- 1. NH4(aq) CN-(aq)
- 2. H2CN(aq) NH2-(aq)
- 3. C2N2(s) 3 H2(g)
19Solution Concentration Molarity
- Molarity moles solute per liter of solution
- 0.30 mol NH3 dissolved in 0.500 LConcentration
- Written like NH3 0.60 M
20pH Scale
- In pure water, a few molecules ionize to form
H3O and OHH2O H2O ? OH H3O - In acidic and basic solutions, these
concentrations are not equalacidic H3O gt
OHbasic OH gt H3Oneutral H3O
OH
21pH Scale
- Measure how much H3O is in a solution using pH
- pH lt 7.0 acidic
- pH gt 7.0 basic
- pH 7.0 neutral
- Measure of H3O and OH concentration (moles per
liter) in a solution - As acidity increases, pH decreases
22pH Scale
- The pH scale is logarithmic100 102 log(102)
210 101 log(101) 11 100 log(100)
00.1 101 log(101) 10.01 102 log(102)
2 - pH log H3O
- pH if H3O 105? 109? Acidic or basic?
- pH if H3O 0.000057 M?
23Finding H3O from pH
- H3O 10-pH
- What is H3O if pH 8.9?
24pH Quantitative Measure of Acidity
- Acidity is related to concentration of H (or
H3O) - pH -logH3O