Neutralization Reactions AcidBaseAcid + Base  Salt + Water Double Replacement HX(aq)MOH(aq)HX(aq) + MOH(aq)  MX(aq) + H 2 O(l) Not Redox Balance by counting atoms

Writing Equations 1.Word Equation 2.Skeleton Equation 3.Balanced Equation –Formulas –Show all the ions –Net Ionic Equation

Formulas for Salts Positive ion 1 st. Negative ion 2 nd. Write down symbols & charges. If charges don’t cancel, use criss-cross rule. HNO 3 + KOH  H 2 O + salt K +1 + NO 3 -1  KNO 3 H 2 SO 4 + KOH  H 2 O + salt K +1 + (SO 4 ) -2  K 2 SO 4

Hydrochloric Acid + Sodium Hydroxide HCl(aq) + NaOH(aq)  NaCl(aq) + H 2 O(l)  Sodium Chloride + Water

HCl(aq) + NaOH(aq)  NaCl(aq) + H 2 O or H + (aq) + Cl - (aq) + Na + (aq) + OH - (aq)  H 2 O(l) + Na + + Cl - (aq) Na+ and Cl- are spectator ions: H + (aq) + OH - (aq)  H 2 O(l)

Nitric Acid + Potassium Hydroxide HNO3(aq) + KOH(aq)  KNO3(aq) + H2O(l)

H + (aq) + NO 3 - (aq) + K + (aq) + OH - (aq)  K + (aq) + NO 3 - (aq) + H 2 O(l) H + (aq) + OH - (aq)  H 2 O

Sulfuric Acid + Calcium Hydroxide H 2 SO 4 (aq) + Ca(OH) 2 (aq)  CaSO 4 (aq) + H 2 O(l)

H 2 SO 4 + Ca(OH) 2  CaSO H 2 O

H 2 SO 4 (aq) + KOH(aq)  ? K 2 SO 4 (aq) + H 2 O(l)

H 2 SO KOH  K 2 SO H 2 O What is the ionic equation? 2H+(aq) + SO4-2(aq) + 2K+ (aq) + 2OH- (aq)  2K+(aq) + SO4-2(aq) + 2H2O(l)

What is the net ionic equation? 2H + (aq) + 2OH - (aq)  2H 2 O(l) Divide through by 2: H + (aq) + OH - (aq)  H 2 O(l)

Hydrochloric Acid + Magnesium Hydroxide HCl + Mg(OH) 2  MgCl 2 + H 2 O

2HCl + Mg(OH)2  MgCl2 + 2H2O What is the ionic equation? H + (aq) + OH - (aq)  H 2 O(l)

2H + (aq) + 2Cl - (aq) + Mg +2 (aq) + 2OH - (aq)  Mg +2 (aq) + 2Cl -1 (aq) + 2H 2 O(l) What is the net ionic equation? 2H + + 2OH -  2H 2 O

For any neutralization reaction The net ionic equation is always: H + + OH -  H 2 O

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

H + (aq) + OH - (aq)  H 2 O(l) 1-to-1 relationship between H + and OH -. At neutralization, # of moles H + = # of moles OH -

Molarity of H + Molarity of H + = moles H + liters of soln Moles H + = Molarity of H + X Liters soln Moles H + = M H+ X V H+

Molarity of OH - Molarity of OH - = moles OH - liters of soln Moles OH - = Molarity of OH - X Liters soln Moles OH - = M OH- X V OH-

At neutralization Moles H + = Moles OH - M H+ X V H+ = M OH- X V OH-

Titration Problems one-to-oneRely on the fact that for all neutralization reactions, there must be a one-to-one ratio of H + to OH -.

M A X V A = M B X V B M A = molarity of H + V A = volume of acid (mls, usually) M B = molarity of OH - V B = volume of base (mls, usually) Holds for monoprotic acid with monohydroxy base, diprotic acid with dihydroxy base, etc.

Modify M a V a = M b V b If the number of H’s in the acid does NOT equal the number of OH’s in the base, this equation MUST be modified: n a M a V a = n b M b V b Where n a = subscript of H in formula for acid and n b = subscript of OH in formula for base.

Molarity of H + In HCl: molarity H + = molarity HCl 2In H 2 SO 4: 2 molarity H + = 2(molarity H 2 SO 4 ) 3In H 3 PO 4 : 3 molarity H + = 3(molarity H 3 PO 4 )

Molarity of OH - In KOH: molarity OH - = molarity KOH 2In Ca(OH) 2 : 2 molarity OH - = 2(molarity Ca(OH) 2 ) Etc.

Titration Movie Titration Movie On the buret, the numbers go down, so you read down. Notice that the volume units will cancel out. They have to be the same, but not necessarily liters.