1. Homework 3-8 Acid/Base Reactions

2. Review of H and the Proton
Hydrogen, the simplest element, consists of a ___________ and an ____________.
If you remove the electron from an H atom, only the proton remains.
Our symbol for a proton is: H+

3. HCl + H2O  Cl– + H3O+ B. Definitions acid conjugate base base
Brønsted-Lowry
Acids are proton (H+) donors.
Bases are proton (H+) acceptors.
HCl + H2O  Cl– + H3O+
acid
conjugate base
base
conjugate acid

4. Example Reactions Which water is the acid and which is the base?
Water can act as either an acid or a base (amphoteric)!
Which is the acid and which is the base?

5. Properties of Acids and Bases
Taste:
Acids sour (vinegar, OJ, wine, aspirin)
Bases bitter (coffee, cigarettes, tonic water, baking soda, antacids, soap)
Feel: Acids sting Bases slippery

6. Properties continued Acids always react with active metals.
Bases generally do not react with metals.
HCl
nitric

7. Properties continued
Solutions of both acids and bases are excellent conductors of electricity (ions are free to move!).
Link to acid dissociation video

8. Indicators
Indicators are chemicals that turn different colors in acids or bases (different pHs).
AciD in litmus = RED, base = bLUE
Acid in phenolphthalein = colorless
Base in phenolphthalein = pink

9. Choices for ?’s : A) Acid B) Base C) Both
1) Turns litmus red
Ans: A
2) Turns phenolpthlein pink
Ans: B
3) Tastes bitter

10. Choices for ?’s : A) Acid B) Base C) Both
4) Feels slippery
Ans: B
5) Solution conducts electricity
Ans: C
6) Always Reacts with active metals
Ans: A

11. Be able to recognize these as Acids or Bases in a chemical rxn
Acids: HCl = Hydrochloric acid
HNO3 = Nitric acid
CH3COOH = Acetic acid (or HC2H3O2)
H2O = water
Bases: NH3 = Ammonia (covalent)
KOH = potassium hydroxide (ionic)
NaOH = sodium hydroxide (ionic)

12. Recognizing Patterns: Acid-Base Conjugate Pairs always differ by an H+
Brønsted-Lowry
Acids are proton (H+) donors.
Bases are proton (H+) acceptors.
HCl + H2O  Cl– + H3O+
acid
conjugate base
base
conjugate acid

13. Recognizing Patterns: Conjugate Acid-Base Pairs
Give the conjugate base for each of the following:
HNO3
NO3 -1
C2H3O2H
C2H3O2-1
HCl
Cl-

14. Recognizing Patterns: Conjugate Acid-Base Pairs
Give the conjugate acid for each of the following:
Cl-
HCl
NH4+1
NH3
H2O
OH -1

15. Example Reaction
NH3 + HCl →
Video Link

16. Amphoteric - can be an acid or a base.
Water is amphoteric
NH3 + H2O  B A
Amphoteric - can be an acid or a base.

17. Water is amphoteric
NH3 + H2O  NH4+ + OH- B A CA CB .

18. Water is amphoteric
H2O + HNO3  A B

19. Water is amphoteric
H2O + HNO3  H3O+ + NO3– B A CA CB

20. Ionic Bases: Must dissociate ions first
NaOH (aq) + HCl(aq) →
Ionic base Acid
Na OH H+ Cl-
H2O + Na Cl- or NaCl
NaOH (aq) + HCl(aq) → H2O + NaCl
HCl + NaOH

21. Recognizing Patterns: Conjugate Acid-Base Pairs
Give the conjugate acid for each of the following:
H2O
NH3
OH-
H3O+
NH4+
H2O