1. Unit 5: (2) Acids and Bases
Physical Science

2. Properties of Acids
Produce H+ (as H3O+) ions in water (the hydronium ion is a hydrogen ion attached to a water molecule)
Taste sour
Corrode metals
Electrolytes
React with bases to form a salt and water
Acid
Base

3. Properties of Acids pH is less than 7 Acid indicators:
Red litmus paper stays red.
Blue litmus paper turns red.
Phenolphthalein stays colorless.
Alkali = Base

4. Properties of Acids React w/ metals to form H2(g) + a metal compound.
Zinc
Hydrochloric acid
Hydrogen bubbles
React w/ metals to form H2(g) + a metal compound.
Zn(s) + 2HCl(aq)  ZnCl2(aq) + H2(g)

5. Some Common Acids Acetic acid C2H4O2 Vinegar
Hydrochloric acid HCl Gastric juice, cleaners
Carbonic acid H2CO3 Club soda
Nitric acid HNO3 Removing warts
Phosphoric acid H3PO4 Found in soft drinks
Lactic acid C3H6O3 Builds up in muscles during workouts

6. Recognizing Acids All acids contain H. Acid formulas begin w/ H.
Not all substances with H in them are acids.
HCl = acid
CH4 = not an acid
When dissolved in H2O, acids form H+ ions.
H+ ion = proton
Acids are proton donors.
H+ ions combine w/ H2O to form H3O+1
H3O+1 = hydronium ion

7. https://www.youtube.com/watch?v=cbN37yRV- ZY

8. Hydronium Ion Production
HCl
H2O
Hydronium Ion Production
Cl-1
H3O+1

9. Properties of Bases Produce OH- ions in water Taste bitter, chalky
Are electrolytes
Feel soapy, slippery
React with acids to form salts and water

10. Properties of Bases pH greater than 7
Can be as poisonous and corrosive as acids.
Base indicators:
Red litmus turns blue.
Blue litmus stays blue.
Phenolphthalein turns pink.
Alkali = Base

11. Some Common Bases NaOH sodium hydroxide lye
KOH potassium hydroxide liquid soap
Ba(OH)2 barium hydroxide stabilizer for plastics
Mg(OH)2 magnesium hydroxide “MOM” Milk of magnesia
Al(OH)3 aluminum hydroxide Maalox (antacid)

12. Recognizing Bases Most bases contain the hydroxide ion, OH-1.
Examples:
NaOH (sodium hydroxide)
KOH (potassium hydroxide)
Ca(OH)2 (calcium hydroxide)
Sr(OH)2 (strontium hydroxide)
Some bases do not contain OH-1 ions:
NH3 (ammonia)
PO4-3 (phosphate ion)
Form OH-1 ion when diss. in H2O.
OH-1 = hydroxide ion
OH-1 + H+1  H2O
Bases are proton acceptors.

13. https://www.youtube.com/watch?v=GrPQv6QE I8Y

14. Acid / Base Reactions
When Acids and Bases are combined a Neutralization reaction produces water and a salt - very important equation!
1. Hydrochloric Acid and Sodium Hydroxide yields water and Sodium Chloride
a. HCl + NaOH  H2O + NaCl
B. H+ + Cl- + Na+ + OH-  H2O + NaCl
2. Salt is an ionic compound formed from an acid / base reaction (neutralization)

15. Acid-Base Neutralization
Rxn between acid and base.
Double replacement rxn.
Products are always a salt and H2O.
Salt = ionic compound (metal + nonmetal)
Examples:
HCl (acid) + NaOH (base)  NaCl (salt) + H2O
2HNO3 (acid) + Ba(OH)2 (base)  Ba(NO3)2 (salt) + 2H2O
3H2SO4 (acid) + 2Al(OH)3 (base)  Al2(SO4)3 (salt) + 6H2O

16. https://www.youtube.com/watch?v=TS- I9KrUjB0

17. Check for Understanding
Acid formulas usually begin with which element?
Answer: H
Base formulas usually end with which polyatomic ion?
Answer: OH-1
Acid-base neutralization reactions produce a salt and _____.
Answer: H2O

18. pH Scale pH
a measure of the concentration of H3O+ ions in solution
measured with a pH meter or an indicator with a wide color range 7
INCREASING
ACIDITY
NEUTRAL
BASICITY 14

19. The pH Scale

20. pH Values of Common Solutions
Battery acid, pH = 1
Lemon juice, pH = 2
Apples, pH = 3
Tomatoes, pH = 4.5
Milk, pH = 6.6
Pure water, pH = 7
Human blood, pH = 7.4
Ammonia, pH = 11
Lime solution, pH = 12 – 13
Lye solution, pH = 13

21. Electrolytes Electrolyte
Substance that conducts an electric current when dissolved.
Produces ions in sol’n.
Salts, acids, and bases.
NaCl (salt)  Na+1(aq) + Cl-1(aq)
HCl (strong acid) + H2O  H3O+1(aq) + Cl-1(aq)
NaOH (strong base)  Na+1(aq) + OH-1(aq)

22. https://www.youtube.com/watch?v=DupXDD87 oHc

23. https://www.youtube.com/watch?v=OMXMlWy bv8A