Topic: Neutralization Reaction

Do Now:

Neutralization Reactions

• AcidHX(aq) + MOH(aq) → MX(aq) +H2O(l)

+ Base → Salt + Water

DR rxn

Acid-Base Titration• A procedure used in order to determine the unknown

molarity of an acid or base• MAVA = MBVB

• (molarity of acid)(volume of acid) = (molarity of base)(volume of base)

• You will know 3 out of the 4 variable

• Standard solution slowly added to unknown solution• As solutions mix:

– neutralization reaction occurs• Eventually:

– enough standard solution is added to neutralize the unknown solution

pH changes during neutralization

• Start with an acid• Add a base• At neutralization

• Start with a base• Add an acid• At neutralization

pH < 7

pH pH = 7

pH > 7

pH

pH = 7

• acid-base indicator needed • WHY?• Usually use phenolphalein• WHY?

When pH = 7 called equivalence point

[H+] = [OH-]

Titration

• End-point = point at which indicator changes color– if indicator chosen correctly:

• end-point very close to equivalence point

MH+1 VH+1 = MOH-1 VOH-1

• If you titrate H2SO4 and NaOH2H+ 1OH+-

Titration Problem #1• In a titration of 40.0 mL of a

nitric acid solution, the end point is reached when 35.0mL of 0.100M NaOH is added

Calculate the concentration of the nitric acid solution

HNO3 + NaOH H2O + NaNO3

Variables

• # of H’s = 1• Ma = ?• Va = 40.0 mL• # of OH’s = 1• Mb = 0.100 M• Vb = 35.0 mL

(1)(X) (40.0 mL) = (0.100 M )(35.0mL)(1)

X = 0.875 M HNO3

Titration Problem #2

• What is the concentration of a hydrochloric acid solution if 50.0 mL of a 0.250M KOH solution is needed to neutralize 20.0mL of the HCl solution of unknown concentration?

KOH + HCl H2O + KCl

(1)(X)(20.0 mL) = (0.250 M) (50.0 mL)(1)

X = 0.625 M HCl

Titration Problem #3

• What is the concentration of a sulfuric acid solution if 50.0mL of a 0.25 M KOH solution is needed to neutralize 20.0mL of the H2SO4 solution of unknown concentration?

H2SO4 + 2 KOH 2 H2O + K2SO4

(2)(X)(20.0ml) = (0.25M)(50.0ml)(1) X = 0.3125 M H2SO4(sulfuric acid)