Types of Chemical Reactions

3221.3.1, 3221.3.2

TargetsTLW covert word equations to symbolic, vice versa.

TLW Identify the reactants, products, and types of different chemical reactions: composition, decomposition, double replacement, single replacement, combustion.

Polyatomic IonsMost polyatomic ions are negatively charged!!

Notice you have 2 polyatomic ions with a positive charge:

NH41+

H3O1+

Acids, Bases, and Salts

As a rule, acids contain an H atom in a compound that can be lost to form an H+ ion.

OH- (hydroxide) is basic.

Salts usually form between a metal and a halogen (recall that halogens are known as salt-formers)

Common AcidsHydrobromic acid HBrHydrochloric acid HClHydrosulfuric acid H2S

Hydrofluoric acid HF

Naming AcidsBinary Acids-contain hydrogen and one other element-hydroelementic acid

H2S hydrosulfuric acid

HBr hydrobromic acidTertiary Acids (Oxyacids) found in Chem. Cruncher-named after element other than oxygen and hydrogen (*notice polyatomic ions)

H2SO4 sulfuric acid H2SO3 sulfurous acid

HClO3 chloric acid HClO2 chlorous acid

HClO hypochlorous acid

Identifying acids and bases from other compounds

HCl (aq) hydrochloric acid HCl (s) hydrogen chlorideHBr (aq) hydrobromic acid HBr (s) hydrogen bromideHF (aq) hydrofluoric acid HF (s) hydrogen fluoride

(aq) dissolved in water(s) solid(l) liquid(g) or ↑ gas∆ heat has been added↔ reversible reaction

aqueous sodium chloride reacts with aqueous lead (II) nitrate to yield a lead (II) chloride precipitate and

aqueous sodium nitrate

aqueous barium nitrate reacts with sulfuric acid [H2SO4(aq)] to yield a barium sulfate precipitate and

nitric acid [HNO3(aq)]

silver nitrate reacts in solution with potassium chromate to yield a silver chromate precipitate and soluble potassium

nitrate

solid calcium carbonate reacts with hydrochloric acid [HCl(aq)] to yield aqueous calcium chloride, carbon

dioxide gas, and liquid water

aqueous zinc chloride reacts with dihydrogen monosulfide gas to yield a zinc sulfide precipitate and

hydrochloric acid

Combustion

• Chemical reaction in which oxygen (O2) reacts with another element forming carbon dioxide (CO2) and water (H2O)

C10H8 + 12 O2 10 CO2 + 4 H2O

Synthesis

• A chemical reaction in which two or more simple compounds combine to form a more complicated one

A + B AB

8 Fe + S8 ---> 8 FeS

Decomposition

• Chemical reaction in which a complicated compound breaks down into two or more simpler compounds

XY X + Y

2 H2O ---> 2 H2 + O2

Single Displacement

• Chemical reaction in which one element trades places with another element in a compound

A + XY AY + X

Mg + 2 H2O ---> Mg(OH)2 + H2

Double Displacement

• A chemical reaction in which the anions and cations of two different molecules switch places, forming two entirely different compounds

AB + XY AY + XB

Pb(NO3)2 + 2 KI ---> PbI2 + 2 KNO3

Acid-Base• Special kind of double displacement reaction that

takes place when an acid and base react with other.• The H+ ion in the acid reacts with the OH- ion in the

base, resulting in the formation of water.

HA + BOH H2O + AB

HBr + NaOH ---> NaBr + H2O

Guch’s Handy Checklist: Follow this series of questions. When you can answer “yes,” STOP!!!

1) Does your reaction have oxygen as one of it's reactants and carbon dioxide and water as products? If yes, then it's a combustion reaction 2) Does your reaction have two (or more) chemicals combining to form one chemical? If yes, then it's a synthesis reaction 3) Does your reaction have one large molecule falling apart to make several small ones? If yes, then it's a decomposition reaction 4) Does your reaction have any molecules that contain only one element? If yes, then it's a single displacement reaction 5) Does your reaction have water as one of the products? If yes, then it's an acid-base reaction 6) If you haven't answered "yes" to any of the questions above, then you've got a double displacement reaction

Practice

1) NaOH + KNO3 --> NaNO3 + KOH

2) CH4 + 2 O2 --> CO2 + 2 H2O

3) 2 Fe + 6 NaBr --> 2 FeBr3 + 6 Na

4) CaSO4 + Mg(OH)2 --> Ca(OH)2 + MgSO4

5) NH4OH + HBr --> H2O + NH4Br

6) Pb + O2 --> PbO2

7) Na2CO3 --> Na2O + CO2