Aim: What happens when you add an acid to a base?

Objectives:1.Students should know the products of a reaction between H+ and OH- (H3O+ and OH-).

2.Students should know the general products of a neutralization reaction.

3.Students should be able to determine the specific products of a reaction between a given acid and a base.

Adding an Acid to a Base

• What ion is the defining ion of an acid?

• What ion is the defining ion of a base?

• What is the product of adding these ions together?

H+ + OH-

H3O+ + OH-

• Why do you think the type of reaction of combining an acid and a base is called a neutralization reaction?

Acid/Base Reactions

What are the products when these ions are part of an acid and a base?

HCl + NaOH

Ca(OH)2 + H2SO4

HNO3 + KOH

Aim: How do we figure out the concentration of an acid or base if it is unknown?

1. Students should know the definition of titration.

2.Students should know why and how the process of titration is done.

3.Students should be able to determine concentration or volume of an acid or base using the formula MAVA= MBVB

4.Students should be able to determine the effect of diprotic acids or dihydroxy bases on a neutralization reaction.5.Students should know how the strength of an acid is determined.

Titration

Indicator

Titration• What is it?

Adding an acid or base of known concentration to an acid or base of unknown concentration until it neutralizes it.

• Why do it? The purpose is to determine the concentration

of the unknown.

• MA x VA = MB x VB Table T

• You will be given 3 variables and will have to solve for the 4th.

Steps in Titration [Example]

1. Add 20 ml of vinegar (acetic acid) to flask.2. Add phenolphthalein. What color should it turn?3. Read the burette containing NaOH to obtain the

initial volume. Slowly add NaOH from the buret to the acid in the flask until the mixture turns a light pink. Record the final volume reading on the burette.

Volume of base added: Vfinal____ - Vinitial _____= _______.1. Given: MB = 1.0 M VA = 20 ml From Titration:VB = ______

Unknown = MA

5. Plug in and solve: MAVA = MBVB

I have an acid of unknown concentration. I’d like to know what the conc. is.

Titration Problems

• If it takes 54 ml of 0.1 M NaOH to neutralize 125 ml of HCl solution, what is the concentration of the HCl?

• If it takes 25 ml of 0.05 M HCl to neutralize 345 ml of NaOH solution, what is the concentration of NaOH?

• If it takes 50 ml of 0.5 M KOH to neutralize 125 ml of H2SO4, what is the concentration of the H2SO4?

Regents Questions

Does the formula of the acid or base affect neutralization?

• What ions are involved in neutralization?

• How might the neutralization between HCl and NaOH differ from the neutralization between HCl and Ca(OH)2?

Monoprotic Acid: HCl 1.0 M HCl has 1.0 mole of H+ ions.

Monohydroxy Base: NaOH 1.0 M NaOH has 1 mole of OH- ions.

Diprotic and Dihydroxy? Triprotic?

Solve the following:

• How many mL of 1.0 M H2SO4 are required to completely neutralize 30 mL of 1.0 M Ca(OH)2?

• How many mL of 1.0 M H2SO4 are required to completely neutralize 30 mL of 1.0 M NaOH?

• How many mL of 0.2 M H3PO4 are required to completely neutralize 10 mL of 0.1 M Mg(OH)2?

What makes an acid or base ‘strong’ or ‘weak’?

The strength of an acid or base is determined by the concentration of H+ ions or OH- they release in solution.

HCl is a strong acid because when dissolved in water, every HCl dissociates into H+ and Cl-.

Ex: 100HCl 100 H+ and 100 Cl-

Nitrous acid is a weak acid because when dissolved in water, not every HNO2 dissociates.

Ex: 100HNO2 25 H+ + 25 NO2- + 75HNO2

NOTE: This concept is different from comparing concentrations of H+ ions in monoprotic and diprotic acids.

Strong Acids

Strong Bases

http://depts.washington.edu/eooptic/links/acidstrength.htmlhttp://www.chemistry.pomona.edu/chemistry/1alab/www/fall2006/powerptpresentations/5anions/acidbaset.htm

Aim: What types of reactions occur with acids and bases?

Objectives:

•Students should be able to identify neutralization reactions and recognize that they are double replacement reactions.

•Students should recognize reactions involving metals and acids as single replacement reactions.

•Students should be able to determine which metals will react with acids

Acid-Base ReactionsDouble Replacement: Neutralization•Acid + Base Water + Salt

– HCl + NaOH H2O + NaCl

– H2SO4 + Ca(OH)2 2H2O + CaSO4

– HNO3 + Mg(OH)2 2H2O + Mg(NO3)2

Single Replacement: Metal + Acid

•Metal + Acid H2(g) + Salt

– Zn + 2HCl H2 + ZnCl2– Mg + H2SO4 H2 + MgSO4

– Cu + HCl NO REACTION (Cu is below H2 on Table J) Which other metals will NOT react with acids to form H2 gas?

Single Replacement Review• Use Table J to determine if single replacement

reactions can occur.– An element can only replace something that is less reactive

than itself. On Table J elements are listed in order of most reactive to least reactive.

This reaction will occur:

Cr + CoCl2 Co + CrCl2Cr can replace the Co in the compound because Cr is higher

than Co on Table J (more active).

This reaction will NOT occur:

Co + CrCl2 NO REACTION

Co is lower on Table J than Cr (less active) so it cannot come in and replace Cr in the compound.

This rule also applies to the right side of the table where nonmetals can replace nonmetals. Cl can replace Br, but Br cannot replace Cl.

Double Replacement Review• Double replacement reactions occur if you create

a new compound. • In a neutralization double replacement reaction,

the new compound that is produced is H2O. HCl + NaOH H2O + NaCl

• In a double replacement reaction involving soluble salts, the new product that is formed is insoluble. If no insoluble product is formed, the double replacement reaction did NOT occur.– NaCl + NH4ClO3 NO REACTION because the

potential products (NaClO3 and NH4Cl) are both soluble.

– Li2SO4 + Ca(OH)2 2LiOH + CaSO4(s) [CaSO4 is insoluble so this reaction will occur.]