Precipitation ReactionsExample: Write the complete balanced molecular equation for the reaction between aqueous solutions of sodium phosphate and calcium acetate. Write the complete ionic equation and the net ionic equation for the reaction.

Precipitation ReactionsExample: Write the equation for the reaction between NH4Cl (aq) and MgSO4 (aq).

Precipitation Reactions

NH4Cl (aq) + MgSO4 (aq) No Reaction

If both products are soluble (aq), then NO REACTION is presumed to occur between the ionic compounds involved. The reaction mixture simple

contains a mixture of soluble ions.

On your exam, you should be able to indicate whether a reaction occurs or not. If it occurs, write the formulas for the products and balance. If no reaction occurs, write the words, “No Reaction.” (You should still show your work!)

Acids & Bases Acids:

Arrhenius definition: substances that ionize to form

one or more hydrogen ions (H+) when dissolved in water

Bronsted-Lowry definition: Proton (hydrogen ion) donor

Acids & Bases Examples of Acids:

HCl hydrochloric acidHNO3 nitric acidHC2H3O2 acetic acidH2SO4 sulfuric acidH3PO4 phosphoric acid

Note: Acids can form different numbers of H+ ions when they ionize!

Acids & Bases Monoprotic acids

have one ionizable H in the formula (HA)

form a single H+ ion when they ionize

HNO3 (aq) H+ (aq) + NO3- (aq)

Acids & Bases Diprotic acids

H2Acan form two H+ ion when they ionize

completely

H2SO4 (aq) 2H+ (aq) + SO42- (aq)

Polyprotic acids:Have two or more ionizable H’s in the

formulaForm two or more H+ ions when they

ionize completely

Acids & Bases Strong Acid:

an acid that is a strong electrolyte ionizes completely in solution

Weak Acid:an acid that is a weak electrolyte

an acid that does not ionize completely

Acids & Bases Strong acids:

Know the names and formulas of the 7 common strong acids:

HCl (aq) hydrochloric acidHBr (aq) hydrobromic acidHI (aq) hydroiodic acidHClO3 chloric acidHClO4 perchloric acidHNO3 nitric acidH2SO4 sulfuric acid

Acids & Bases Examples of Weak Acids

HF (aq) hydrofluoric acidH3PO4 phosphoric acidHC2H3O2 acetic acid

Acids & Bases Bases:

substances that accept (react with) H+ ions.

any substance that increases the OH- concentration when added to water

Examples:

NaOH (aq) Na+ (aq) + OH- (aq)

Ca(OH)2 (aq) Ca2+ (aq) + 2 OH- (aq)

Acids & Bases Examples of Bases (cont):

Ammonia (NH3) Does not contain OH-

Accepts H+ ion from water and increases the OH- concentration in the water

NH3(aq) + H2O (l) NH4+ (aq) + OH-

(aq)

NH3 is a weak electrolyte!!

Acids & Bases Strong Base:

a base that is a strong electrolyte ionizes completely in solution

Weak Base:a base that is a weak electrolytedoes not ionize completely in

solution

Acids & Bases Strong Bases: Know the names and

formulas of the strong bases

Alkali metal (1A) hydroxidesLiOH lithium hydroxideNaOH sodium hydroxideKOH potassium hydroxide

RbOH rubidium hydroxide

CsOH cesium hydroxide

Acids & Bases Strong bases to know (con’t):

Heavy alkaline earth metal (2A) hydroxidesCa(OH)2 calcium hydroxideSr(OH)2 strontium hydroxide

Ba(OH)2 barium hydroxide

Acids & Bases Examples of Weak Bases:

ammonia (NH3)sodium bicarbonate (NaHCO3)

baking soda a component of Alka-Seltzer

Acid-Base Reactions Reactions between acids and bases are

called neutralization reactions.

HCl (aq) + NaOH (aq) H2O (l) + NaCl (aq)

Salt:any ionic compound whose cation

comes from a base and whose anion comes from an acid

An ionic compound that is neither an acid nor a base

salt

Acid-Base Reactions In general the equation for the

neutralization of any acid by a metal hydroxide is:

acid + metal hydroxide a salt + water

2 HC2H3O2 (aq) + Ca(OH)2 Ca(C2H3O2)2 (aq) + 2 H2O (l)

H3PO4 (aq) + 3 KOH (aq) K3PO4 (aq) + 3 H2O (l)

Neutralization reactions are a type of metathesis reaction.

Acid-Base Reactions To predict the products of a

neutralization reaction:

identify the ions presentexchange anionswrite the correct formulas for the

products including physical stateswrite a balanced equation

Acid-Base ReactionsExample: Write the balanced equation for the reaction between aqueous solutions of HBr and Ca(OH)2.

Acid-Base Reactions You can also write complete and net

ionic equations for acid-base reactions:

Complete ionic equation:

Molecular equation:

2HBr (aq) + Ca(OH)2 (aq) CaBr2 (aq) + 2H2O (l)

2 H+ (aq) + 2Br- (aq) + Ca2+ (aq) + 2 OH- (aq) Ca2+ (aq)

+ 2 Br- (aq) + 2 H20 (l)

Acid-Base Reactions

Net ionic equation:

H+ (aq) + OH- (aq) H2O (l)

Note: This is the net ionic equation between any strong acid and strong base.

Complete ionic equation:

2 H+ (aq) + 2Br- (aq) + Ca2+ (aq) + 2 OH- (aq) Ca2+ (aq) + 2 Br- (aq) + 2 H20

(l)

Acid-Base ReactionsExample: Write the balanced molecular equation for the reaction between Mg(OH)2 (s) and HCl (aq). Write the complete ionic and net ionic equations.

Acid-Base ReactionsExample: Write the balanced molecular equation for the reaction between aqueous solutions of sodium hydroxide and phosphoric acid. Write the complete ionic and net ionic equations.

Acid-Base Reactions There are many bases that do not

contain OH-

Na2SNaCNNa2CO3NaHCO3

These bases react with acids to form gaseous products instead of water.

Acid-Base Reactions

Examples:

KCN (aq) + HCl (aq) HCN (g) + KCl (aq)

HBr (aq) + NaHCO3 (aq) NaBr (aq) + H2CO3 (aq)

but:H2CO3 (aq) H2O (l) + CO2 (g)

so:

HBr (aq) + NaHCO3 (aq) NaBr (aq) + H2O (l) + CO2 (g)

Acid-Base Reactions You should remember the following

physical states/reactions for the exam.

H2S (g)

HCN (g)

H2CO3 (aq) H2O (l) + CO2 (g)