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CHAPTER 19 NOTES: ACIDS, BASES AND NEUTRALIZATION
ACIDS: substances that give H+ (a proton) to water pH < 7 [H+] > [OH- ] [ ] means “the molarity of..”
Review: Formula Writing for Acids
binary acids: hydro___________ ic acid (DOESN’T have O!)
ex: HCl: ___ hydrochloric acid _______ HBr: ___ hydrobromic acid _____
H 2 S: ___ hydrosulfuric acid ______ H 3 N: ___ hydronitric acid ________
ternary acids: “ate-ic-ite-ous”
ate = ic
ex: sulfuric acid (sulfate) ____H 2 SO 4 _____________________________
nitric acid (nitrate) ____HNO 3 _____________________________
HC 2 H 3 O 2 ____acetic acid_____________________________
ite = ous
ex: sulfurous acid (sulfite) _____H 2 SO 3 ____________________________
nitrous acid (nitrite) _____HNO 2 ____________________________
H 3 PO 3 _____phosphorous acid____________________________
Strong Acids: HCl – hydrochloric acid
HBr – hydrobromic acid
HI – hydroiodic acid
HNO 3 – nitric acid
H 2 SO 4 – sulfuric acid
HClO 3 – chloric acid
HClO 4 – perchloric acid
Weak Acids: Ex: vinegar – acetic acid HC 2 H 3 O 2
Dissociation of Strong Acids
HCl H+^ + OH-
H 2 SO 4 2 H+^ + SO 4 -
Dissociation of Weak Acids
HC 2 H 3 O 2 ↔ H+^ + C 2 H 3 O 2 -
Dissociation of Water:
H 2 O ↔ H +^ + OH-^ water inself ionizes into H+ and OH-, but only to a very small extent. All water based solutions have H+ and OH-. If there is more H+ the solution is acidic. If there is more OH- it is basic. pH
pH = -log [H+] pOH = -log[OH-]
pH + pOH = 14 [H+] x [OH-] = 1.0 x 10-14^ M
Acids: pH < 7 Bases: pH > 7 Neutral: pH = 7
Try: Solution Acid or Base?
[H+] [OH-] pH pOH
0.010M HCl Acid 0.010M (10-^2 M)
10 -^12 M 2 12
0.00010M
HNO 3
Acid 0.00010M (10-^4 M)
10 -^10 M 4 10
1 x 10-^6 M HI Acid 10 -^6 M 10 -^8 M 6 8
0.0010M
NaOH
Base 10 -^11 M 0.0010M 11 3
Windex Base 10 -^12 M 0.010M 12 2
Lemon Juice Acid 0.0010M (10-^3 M)
10 -^11 M 3 11
Sprite Acid 0.00010M (10-^4 M)
10 -^10 M 4 10
Ammonia Base 10 -^12 M 0.010M 12 2
Milk Acid 10 -^6 M 10 -^8 M 6 8
PROPERTIES OF ACIDS & BASES: MINI LAB
Safety: Acids and Bases are caustic. If you spill an acid in lab, neutralize with baking soda before cleaning up with water. If you spill a base in lab, neutralize with a weak vinegar solution before cleaning up with water. If you spill and acid OR base on your skin, flush with plenty of water (DO NOT neutralize).
- Conductivity
- Clean and dry a well plate thoroughly.
- Add 5 drops of each solution into the well plate.
- Use your conductivity tester to test whether or not each solution conducts electricity. Be sure to clean off the tester with distilled water after each solution!
- Record observations in the chart below:
Solution Conducts? Yes or No? To what extent?
Alcohol (^) No
Distilled water (^) No
Hydrochloric acid (^) Yes, brightly
Sodium hydroxide (^) Yes, brightly
Gatorade (^) Yes, brightly
a) Use your textbook to define the term electrolyte: ___ compound that conducts an electric
current when it is in an aqueous solution (includes all ionic compounds)
b) What do solutions need to conduct electricity? ____ ions dissociated in solution
c) What ions are in a solution of hydrochloric acid? ____ H+1, Cl-1^ ___________________
d) What ions are in a solution of sodium hydroxide? ___ Na+1, OH-1^ __________________
e) Why do you think Gatorade conducts electricity if it is not an acid or a base? ____
Gatorade contains electrolytes which conduct electricity
- Exploring with Indicators
- Add 5 drops of each solution into a clean well plate. Be sure you identify for yourself which well contains which solution.
- Test each well using pH paper. Match the color of the pH paper to the scale and record readings in the data table below.
- Test each well using the red litmus paper. Record observations in the data table below.
- Test each well using the blue litmus paper. Record observations in the data table below.
- Add one drop of phenolphthalein into each well. Record observations in the data table below.
- Clean and dry well plate thoroughly.
- Add 5 drops of each solution into a clean well plate. Be sure you identify for yourself which well contains which solution.
- Add one drop of universal indicator into each well. Record observations in the data table below.
- Clean and dry the well plate thoroughly.
Solution pH paper Red litmus Blue litmus Phenolphthalein Universal indicator
A B C D E
Other properties of Acids and Bases:
Common household acids include citrus, vinegar, and yogurt. Based on your experience with
these items, acids taste _____ sour _____________.
Common household bases include bleach, soap, and baking soda. Based on your experience
with these items, bases taste _________ bitter __________________. Bases feel
___slippery_______________ to the touch.
Both acids and bases are ____ caustic _____. If you spill acid in lab, you should neutralize it
with ___ baking soda ________ before cleaning up. If you spill a base in lab, you should neutralize it
with _____ weak vinegar ______ before cleaning up.
a) Use the pH (from your data) of the unknown solutions to complete the pH chart below:
Solution Acid or Base?
[H+] [OH-] pH pOH
A
B
C
D
E
b) What volume of 0.01M HCl is needed to completely react with 2.0g magnesium ribbon?
RXN: _______2 HCl + Mg MgCl 2 + H 2 _____________
2.0g Mg 1 mol Mg 2 mol HCl 1L HCl = 16.5L HCl 24.3g Mg 1 mol Mg 0.01mol HCl
c) A student spills 5mL of sulfuric acid on the lab table. To neutralize the acid, he pours sodium hydroxide on it and forms sodium sulfate and water. If the initial concentration of the sulfuric acid solution is 0.010M, find the mass of sodium sulfate formed.
RXN: ______ H 2 SO 4 + 2 NaOH Na 2 SO 4 + 2 HOH ___________
0.005L .01 mol H 2 SO 4 2 mol HOH 18g HOH = 0.0018g HOH
1 L H 2 SO 4 1 mol H 2 SO 4 1 mol HOH
NEUTRALIZATION REACTIONS
Acid + Base Salt (Ionic Compound) + Water
Example: Sodium hydroxide + hydrochloric acid
NaOH + HCl NaCl + H 2 O (HOH)
Potassium hydroxide + nitric acid
KOH + HNO 3 KNO 3 + H 2 O
Lithium hydroxide + sulfuric acid
2LiOH + H 2 SO 4 Li 2 SO 4 + 2H 2 O
Barium hydroxide + phosphoric acid
3 Ba(OH) 2 + 2 H 3 PO 4 Ba 3 (PO4) 2 + 6 H 2 O
Acetic acid + sodium hydroxide
HC 2 H 3 O 2 + NaOH NaC 2 H 3 O 2 + H 2 O
TITRATION A method of finding the molarity of an unknown solution by reacting it with a solution of known molarity
# H’s in solution = # OH’s in solution
(# H in Acid) x (Macid) x (Vacid) = (# OH in Base) x (Mbase) x (Vbase)
Titration Problems:
a. What volume of 0.15M sodium hydroxide solution is needed to react with 12.2mL of 0.350M hydrochloric acid?
(# H in Acid) x (Macid) x (Vacid) = (# OH in Base) x (Mbase) x (Vbase)
1 x 12.2mL x 0.350M = 1 x 0.15M x V
V = 28.5mL
b. What volume of 0.250M nitric acid is needed to react with 20.5mL of 0.10M lithium hydroxide?
(# H in Acid) x (Macid) x (Vacid) = (# OH in Base) x (Mbase) x (Vbase)
1 x V x 0.250M = 1 x 0.10M x 20.5mL
V = 8.2mL
c. Find the molarity of an unmarked hydrochloric acid solution of 14.51mL of the solution reacts completely with 12.24mL of 0.030M sodium hydroxide solution.
(# H in Acid) x (Macid) x (Vacid) = (# OH in Base) x (Mbase) x (Vbase)
1 x 14.51mL x M = 1 x 0.030M x 12.24mL
V = 0.025mL
d. Find the molarity of a nitric acid solution if 10.4mL of the solution is needed to react with 25.0mL of 0.45M barium hydroxide.
(# H in Acid) x (Macid) x (Vacid) = (# OH in Base) x (Mbase) x (Vbase)
1 x 10.4mL x M = 25mL x 0.45M x 2 (2 because Ba(OH) 2 has two hydroxides)
V = 2.16 M
