1. 6.5- The Strength of Acids and Bases

2. Strong acids A strong acid is an acid that reacts almost completely ( >99%) with water to form hydronium ions HCl (aq) +H 2 O (l) >99% H 3 O + + Cl - (aq) Most common strong acids are HCl (aq), H 2 SO 4(aq), and H 2 NO 3(aq) Strong acids have a low pH level, the higher the pH level the weaker the acid

3. Strong acids Good conductors of electricity Fast reaction with water Almost complete reaction with water pH<<7

4. Weak Acids Most acids are weak acids Less than 50% reacts with water to produce hydronium ions CH 3 COOH (aq) +H 2 O (l) <50% H 3 O + (aq) +CH 3 COO (aq) pH<7 low conductivity slow reaction rate partially reacts with water to form H 3 O + (aq)

5. Strong Bases completely to form OH - (aq) NaOH (aq) Na + (aq) + OH - (aq) high conductivity Fast reaction rate Very high pH (pH>>7)

6. Weak Bases Partially reacts with water to form OH - (aq) NH 3(aq) + H 2 O (l) <50% OH - (aq) +NH 4 (aq) Slow reaction rate Low conductivity Medium pH ( pH>7)

7. Polyprotic Substances Monoprotic acids are acids that can react only once with water ( like HCl (aq) ) Polyprotic acids are able to react more than once with water Ex) H 3 PO 4(aq) +H 2 O (l) <50% H 2 PO 4 - (aq) +H 3 O + (aq) H 2 PO 4 - +H 2 O (l) <1% HPO 4 2- (aq) +H 3 O + (aq) HPO 4 2- (aq) +H 2 O (l) 0% PO 4 3- (aq) +H 3 O + (aq)

8. With polyprotic acids, their reaction with water decreases with every step. Typically polyprotic acids are weaker than monotropic acids

9. The same idea works with polyprotic bases, they react more than once with water CO 3 2- (aq) + H 2 O (l) <50% OH - (aq) + HCO 3 – (aq) HCO 3 – (aq) + H 2 O (l) <1% OH - (aq) +H 2 CO 3 (aq) The reaction with water decreases with every step

10. assignment Read page 255-259 Do pg 256 #1,2,4 pg 257#7,9 pg 259 #1,3,5,7,12