Mr. Storie
40S Chemistry
Student– Acid and bases Unit
Acids and Bases
1
Mr. Storie
40S Chemistry
Student– Acid and bases Unit
UNIT 4: ACIDS & BASES OUTCOMES
All important vocabulary is in Italics and bold.
•
Outline the historical development of acid base theories.
Include: Arrhenius, Bronsted-Lowry, Lewis.
•
Write balanced acid/base chemical equations.
Include: conjugate acid/base pairs, amphoteric behavior.
•
Distinguish between strong and weak acids and bases.
Include: electrolytes and non-electrolytes
•
Describe the relationship between the hydronium and hydroxide ion concentrations in water
Include: the ion product of water, Kw
•
Formulate an operational definition of pH.
•
Solve problems involving pH.
•
Describe how an acid-base indicator works in terms of colour shifts and Le Chatelier’s Principle.
•
Write the equilibrium expression (Ka or Kb) from a balanced chemical equation.
•
Use Ka or Kb to solve problems for pH, percent dissociation and concentration.
•
Predict whether an aqueous solution of a given ionic compound will be acidic, basic or neutral given the
formula.
•
Write balanced neutralization reactions involving strong acids and bases.
•
Calculate the concentration or volume of an acid or base from the concentration and volume of an acid or
base required for neutralization.
•
Using a standardized acid or base, determine the concentration of an unknown base or acid.
Additional KEY Terms
monoprotic
salt hydrolysis
standard solution
titration
diprotic
concentrated
end point
amphoteric
dilute
equivalence point
Relative Strengths of Acids
2
Mr. Storie
40S Chemistry
Student– Acid and bases Unit
*Acids 1.0 mol/L in water at 25ºC
Acid
Reaction
Perchloric acid
HClO4 + H2O → H3O+ + ClO4¯
Hydriodic acid
HI + H2O → H3O+ + I¯
Hydrobromic acid
HBr + H2O → H3O+ + Br¯
Hydrochloric acid
HCl + H2O → H3O+ + Cl¯
Nitric acid
HNO3 + H2O → H3O+ + NO3¯
Sulfuric acid
H2SO4 + H2O → H3O+ + HSO4¯
Oxalic acid
H2C2O4 + H2O → H3O+ + HC2O4¯
Sulfurous acid
H2SO3 + H2O → H3O+ + HSO3¯
Hydrogen sulfate ion
HSO4¯ + H2O → H3O+ + SO42¯
Phosphoric acid
H3PO4 + H2O → H3O+ + H2PO4¯
Ferric ion
Fe(H2O)63+ + H2O → H3O+ + Fe(H2O)5(OH)2+
Hydrogen telluride
H2Te + H2O → H3O+ + HTe¯
Hydrofluoric acid
HF + H2O → H3O+ + F¯
Nitrous acid
HNO2 + H2O → H3O+ + NO2¯
Hydrogen selenide
H2Se + H2O → H3O+ + HSe¯
Chromic ion
Cr(H2O)63+ + H2O → H3O+ + Cr(H2O)5(OH)2+
Benzoic acid
C6H5COOH + H2O → H3O+ + C6H5COO¯
Hydrogen oxalate ion
HC2O4¯ + H2O → H3O+ + C2O42¯
Acetic acid
HC2H3O2 + H2O → H3O+ + C2H3O2¯
Aluminum ion
Al(H2O)63+ + H2O → H3O+ + Al(H2O)5(OH)2+
Carbonic acid
H2CO3 + H2O → H3O+ + HCO3¯
Hydrogen sulfide
H2S + H2O → H3O+ + HS¯
Dihydrogen phosphate ion
H2PO4¯ + H2O → H3O+ + HPO42¯
Hydrogen sulfite ion
HSO3¯ + H2O → H3O+ + SO32¯
Ammonium ion
NH4+ + H2O → H3O+ + NH3
Hydrogen carbonate ion
HCO3¯ + H2O → H3O+ + CO32¯
Hydrogen telluride ion
HTe¯ + H2O → H3O+ + Te2¯
Hydrogen peroxide
H2O2 + H2O → H3O+ + HO2¯
Monohydrogen phosphate
HPO42¯ + H2O → H3O+ + PO43¯
Hydrogen sulfide ion
HS¯ + H2O → H3O+ + S2¯
Water
H2O + H2O → H3O+ + OH¯
Hydroxide ion
OH¯ + H2O → H3O+ + O2¯
Ammonia
NH3 + H2O → H3O+ + NH2¯
Ka
very large
very large
very large
very large
very large
very large
5.4 x 10¯2
1.7 x 10¯2
1.3 x 10¯2
7.1 x 10¯3
6.0 x 10¯3
2.3 x 10¯3
6.7 x 10¯4
5.1 x 10¯4
1.7 x 10¯4
1.5 x 10¯4
6.6 x 10¯5
5.4 x 10¯5
1.8 x 10¯5
1.4 x 10¯5
4.4 x 10¯7
1.0 x 10¯7
6.3 x 10¯8
6.2 x 10¯8
5.7 x 10¯10
4.7 x 10¯11
1.0 x 10¯11
2.4 x 10¯12
4.4 x 10¯13
1.2 x 10¯15
1.8 x 10¯16
< 10¯36
very small
POLYATOMIC IONS
3
Mr. Storie
40S Chemistry
NAME
ACETATE
AMMONIUM
HYDROGEN CARBONATE (BICARBONATE)
CARBONATE
CHLORATE
CHLORITE
CHROMATE
DICHROMATE
DIHYDROGEN PHOSPHATE
HYDROGEN PHOSPHATE
PHOSPHATE
HYDROGEN SULFATE (BISULFATE)
SULFATE
HYDROGEN SULFITE (BISULFITE)
SULFITE
HYDRONIUM
HYDROXIDE
PERCHLORATE
HYPOCHLORITE
NITRATE
NITRITE
PERMANGANATE
THIOCYANATE
Student– Acid and bases Unit
FORMULA
CH3COONH4+
HCO3CO3-2
ClO3ClO2CrO4-2
Cr2O7-2
H2PO4HPO4-2
PO4-3
HSO4SO4-2
HSO3SO3-2
H 3O +
OHClO4ClO- (OCl-)
NO3NO2MnO4SCN-
CHARGE
-1
+1
-1
-2
-1
-1
-2
-2
-1
-2
-3
-1
-2
-1
-2
+1
-1
-1
-1
-1
-1
-1
-1
Patterns for Naming Polyatomic Ions
‘-ate’ ending is the general (base) form. The ending changes depending on the
number of oxygen atoms – notice the charge remains the same in these cases.
ClO3ClO4ClO2ClO-
chlorate
perchlorate
chlorite
hypochlorite
base oxygen atoms
base + 1 oxygen atom
base – 1 oxygen atom
base – 2 oxygen atoms
4
Mr. Storie
1.
40S Chemistry
Student– Acid and bases Unit
*FOLLOW THE MOVING HYDROGEN ION*
Identify the acid, base, conjugate acid and conjugate base for each of the following.
a) HClO4 (aq) + H2O (l)  H3O+ (aq) + ClO4¯ (aq)
b) H2SO3 (aq) + H2O (l)  H3O+ (aq) + HSO3¯ (aq)
c) HC2H3O2 (aq) + H2O (l)  H3O+ (aq) + C2H3O2¯ (aq)
d) H2S (g) + H2O (l)  H3O+ (aq) + HS¯ (aq)
e) HSO3- (aq) + H2O (l)  H3O+ (aq) + SO3¯2
(aq)
f) NH3 (g) + H2O (l)  NH4+ (aq) + OH¯ (aq)
g) HF (aq) +
HSO3¯ (aq)  F¯ (aq) + H2SO3 (aq)
h) HNO2 (aq) + HS¯ (aq)  NO2¯ (aq) + H2S (aq)
2.
Predict which reactant will accept a hydrogen ion and complete the products for each equation.
• Label each reactant as an acid or base.
• List under the first reactant whether it falls under the Arrhenius (A) and/or Bronsted-Lowry (B-L)
definition of an acids/bases
E.g.
HBr (aq) + H2O (l)  H3O+ (aq) + Br¯ (aq)
Acid
Base
(A and B-L)
a) HI (aq) + H2O (l) 
b) HF (aq) + H2O (l) 
c) H2CO3 (g) + H2O (l) 
d) CO3-2 (aq) + H2O (l) 
e) O-2 (aq ) + H2O (l) 
f) HSO3¯ (aq) + H2O (l) 
5
Mr. Storie
40S Chemistry
Student– Acid and bases Unit
Write the dissociation of each of the following in water. Predict whether each of the
following will be an electrolyte or non-electrolyte.
1. NaOH (s) 
2. Na2CO3 (s) 
3. Mg(OH)2 (s) 
4. C6H12O6 (s) 
5. HCl (g) 
6. K3PO4 (s) 
7. H2SO4 (aq) 
8. NaC2H3O2 (s) 
9. (NH4)2SO4 (s) 
10. C2H5OH (l) 
11. H3PO4 (aq) 
12. CaCl2 (s) 
6
Mr. Storie
40S Chemistry
Student– Acid and bases Unit
1. In each case:
i. Complete the acid-base equation with the help of tables if needed.
ii. ii. Label the acid, base, CA, CB.
iii. Explain whether the reactants or products are favored at equilibrium.
a)
H3PO4 + C2H3O2–
b)
C2H3O2– + HSO4–
c)
SO32– + NH4+
d)
HO2– + H2CO3
e)
Al(H2O)63+ + HSe–
2. List the following in decreasing (strongest to weakest) order of strength as bases.
a. CO32– b. HCO3– c. HPO42– d. CH3COO– e. HSO3–
3. List the following substances in increasing order (weakest to strongest) of strength as acids and bases.
Some may be used more than once.
F– , H2PO4– , HSO4– , H2S , C2H3O2– , HNO2 , HTe–
7
Mr. Storie
40S Chemistry
Student– Acid and bases Unit
ANSWER THE FOLLOWING QUESTIONS ABOUT Kw AND ION CONCENTRATION:
1. What is the hydroxide ion concentration in a solution with an hydronium concentration of 6.80×10–10
mol/L?
2. What is the [H3O+] in a solution with [OH–] of 5.67×10–3?
3. If the [H3O+] in a nitric acid solution is 0.0020 mol/L, what is the [OH–]?
4. If the [OH¯] in a sodium hydroxide solution is 0.050 mol/L, what is [H3O+]?
5. 0.25 moles of hydrogen chloride gas is dissolved in 2.0 L of water. Write the dissociation equation for this
gas and calculate both [H3O+] and [OH–].
6. 10.0 g of lithium hydroxide is dissolved in 750 mL of water. Write the dissociation equation and calculate
both [H3O+] and [OH–].
7. 10.0 g of calcium hydroxide is dissolved in 400.0 mL of solution. Write the dissociation equation and
calculate both [H3O+] and [OH–].
8. If the [H3O+] of a barium hydroxide solution is 1.0×10–13 mol/L, calculate the [OH–]. How many grams of
barium hydroxide must have been used to make a Litre of this solution?
9. Calculate the [H3O+] in milk of magnesia (magnesium hydroxide) that has an [OH–] of 1.43×10–4 mol/L.
Answer Key
1) 1.47 x 10-5 M, 2) 1.76 x 10-12 M, 3) 5.0 x 10-12 M, 4) 2.0 x 10-13 M, 5) 0.125 M, 8.0 x 10-14 M
6) 1.79 x 10-14 M, 0.559 M 7) 1.48 x 10-14 M, 0.675 M 8) 8.6 g, 9) 6.99 x 10 -11 M
8
Mr. Storie
40S Chemistry
ANSWER THE FOLLOWING QUESTIONS ON pH and pOH:
1.
2.
3.
Determine the pH of each of the following values
a. [H+] = 1.0 x 10-6
b. [H+] = 1.0 x 10-8
c. [OH¯] = 1.0 x 10-2
d. [OH¯] = 1.0 x 10-5
e. [H+] = 2.0 x 10-3
f. [H+] = 3.5 x 10-4
g. [OH¯] = 7.50 x 10-7
h. [OH¯] = 9.0 x 10-9
Determine the concentration of [H+] of each of the following.
a. pH = 7.00
b. pOH = 5.00
c. pH = 13.00
d. pOH = 11.00
e. pH = 3.40
f. pOH = 6.10
g. pH = 8.90
h. pOH = 13.80
Determine the pOH of the following if the pH is given
a. pH = 5.40
b. pH = 8.60
c. pH = 2.90
4.
d. pH = 12.60
Determine the concentration of the OH¯ ions in solutions with the following pH values.
a. pH = 4.10
b. pH = 5.10
c. pH = 1.60
5.
Student– Acid and bases Unit
d. pH = 9.20
Calculate pH of each of the following solutions.
a. 0.0020 mol/L HCl
b. 0.050 M NaOH
c. 4.0 x 10-4 M Ba(OH)2
Answers
a. 6.00
a. 1e-7
a. 8.60
a. 2.70
b.
b.
b.
b.
8.00
1e-9
5.40
12.70
c.
c.
c.
c.
12.0
1e-13
11.10
10.90
d. 0.50 mol/L HNO3
d.
d.
d.
d.
9.00
1e-3
1.40
0.30
e. 2.70
e. 4e-4
a. 1.3e-10
f. 3.46
f. 1.3e-8
b. 1.3e-9
g. 7.88
g. 1.3e-9
c. 4e-13
h. 5.95
h. 0.63
d. 1.6e-5
9
Mr. Storie
40S Chemistry
Student– Acid and bases Unit
pH practice
1)
What is the pH and pOH of a 1.2 x 10-3 M HBr solution?
2)
What is the pH and pOH of a 2.34 x 10-5 NaOH solution?
3)
What is the pH and pOH of a solution made by adding water to 15 grams of hydroiodic acid until the
volume of the solution is 2500 mL?
4)
What is the pH and pOH of a solution that was made by adding 400 mL of water to 350 mL of 5.0 x 10-3
M NaOH solution?
5)
What is the pH and pOH of a solution with a volume of 5.4 L that contains 15 grams of hydrochloric
acid and 25 grams of nitric acid?
6)
A swimming pool has a volume of one million liters. How many grams of HCl would need to be added
to that swimming pool to bring the pH down from 7 to 4? (Assume the volume of the HCl is negligible)
ANSWER KEY
1. pH: 2.9 pOH: 11.1
4. pOH: 2.7 pH: 11.3
2. pOH: 4.6 pH: 9.4
5. pH: 0.82 pOH: 13.18
3. pH: 1.3
6. 3545 g
pOH: 12.7
10
Mr. Storie
40S Chemistry
ANSWER THE FOLLOWING DISSOCIATION QUESTIONS:
Student– Acid and bases Unit
1.
Calculate the concentration of all species in a 0.70 mol/L HNO3 solution.
2.
Determine the [H3O+] in 0.90 mol/L solution of weak acid H2S. (Ka = 1.0 x 10-7) (3.0x 10-4 M)
3.
Find the concentration of all species in a 0.10 M solution of NaOH.
4.
Determine the concentration of all species in a 0.65 mol/L solution of an ammonia, if the base
dissociation constant is 1.8 x 10-5. (3.4 x 10-3 M)
5.
Find the [H+] in a 0.86 M solution of the weak acid H2O2. (Ka = 2.4 x 10-12) (1.4 x 10-6 M)
6.
If [H3O+] = 4.5 x 10 -6 mol/L in a 0.45 mol/L solution of the weak acid HX, calculate percent
dissociation. (0.001%)
7.
Find the percent dissociation in 0.87 M solution of the weak base HPO42¯ if Kb is
1.6 x 10-7. (0.043%)
11
Mr. Storie
40S Chemistry
Student– Acid and bases Unit
+
8.
Calculate the [H ] of a 0.38 mol/L weak acid that is dissociated 0.12%. (4.56 x 10-4 M)
9.
Determine the Ka for an acid, HA, if a 0.45 M solution is dissociated 0.025%. (2.8 x 10-8)
10. Calculate the the percent dissociation of a 0.60 mol/L aniline (C6H5NH2) solution (Kb = 3.8×10–10) if it
dissociates according to the following equation: (0.0025%)
C6H5NH2 + H2O
C6H5NH3+ + OH–
11. Determine the Ka for an acid HA if a 0.750 mol/L solution is dissociated 0.015%. (1.7 x 10-8)
12. If [H3O+] = 4.5 ×10–10 mol/L, calculate the Ka for a weak acid in a solution of 0.80 mol/L of an acid HB.
(2.5 x 10-19)
13. Calculate the pH of a 0.10 mol/L solution of hypochlorous acid, HOCl (Ka = 3.5 ×10–8) (4.2)
12
Mr. Storie
40S Chemistry
Student– Acid and bases Unit
2–
14. A 0.20 mol/L solution of the weak base HPO4 has a pH of 9.00. Find the Kb. (5.0 x 10-10)
15. Calculate the Ka of a weak acid, HX, if a 0.25 mol/L solution has a pH of 4.40. (6.3 x 10-9)
16. At 25°C, a 0.010 mol/L ammonia solution is 4.3% ionized. Calculate the pOH and pH. (3.4, 10.6)
17. Hydrazine (N2H4) is a weak base with a Kb of 3.0×10–6. The reaction of hydrazine in water is
H2NNH2 + H2O
H2NNH3+ + OH–
Calculate the the pH of a 2.0 mol/L solution of hydrazine. (11)
18. Calculate the percent dissociation of a 0.20 mol/L solution of the weak acid, HNO2, if the pH of the
solution is 4.20. (0.032%)
13
Mr. Storie
40S Chemistry
ANSWER THE FOLLOWING DISSOCIATION QUESTIONS:
Student– Acid and bases Unit
1.
Calculate the original concentration of the weak base, C2H3O2¯ (acetate ion), if [OH¯] = 1.5 x 10-5 and
Kb = 5.6 x 10-10. (0.4 M)
2.
Calculate percent dissociation of a 0.60 M aniline (C6H5NH2) solution (Kb = 3.8 x 10-10) if it dissociates
according to the following equation: (0.0025%)
C6H5NH2 + H2O  C6H5NH3+ + OH¯
3.
Determine the Ka for an acid HA if a 0.750 M solution is dissociated 0.015%. (1.7 x 10-8)
4.
Compute the concentration of [OH¯] in a 0.75 mol/L solution of Mg(OH)2.
5.
If [H3O+] = 4.5 x 10-10 mol/L, calculate Ka in a solution of 0.80 mol/L of an acid HB. (2.5 x 10-19)
6.
Determine the concentration of all species plus the percent dissociation in a 0.60 mol/L ammonia
solution. (Kb = 1.8 x 10-5) (3.3 x 10-3 M, 3.3 x 10-3M, 0.6 M, 0.55%)
7.
Calculate the concentration of a solution of acetic acid (Ka = 1.8 x 10-5) with pH = 3.00.
(0.056)
14
Mr. Storie
40S Chemistry
Student– Acid and bases Unit
Are each of the following salts acidic, basic or neutral in water? Explain why.
1. Sodium sulfate
2. Potassium phosphate
3. Sodium nitrate
4. Sodium sulfide
5. Potassium chloride
6. Magnesium nitrate
7. Iron (III) Nitrate
8. Sodium carbonate
9. Potassium oxalate
10. Ammonium iodide
11. Potassium acetate
12. Chromium (III) bromide
13. Potassium dihydrogen phosphate
14. Sodium nitrite
15. Calcium oxide
15
Mr. Storie
40S Chemistry
ANSWER THE FOLLOWING NEUTRALIZATION QUESTIONS:
Student– Acid and bases Unit
1.
Write the complete reaction that occurs when the following acid and bases are reacted.
a) Hydrochloric acid and sodium hydroxide.
b) Sulfuric acid and potassium hydroxide.
c) Nitric acid and calcium hydroxide.
d) Phosphoric acid and lithium hydroxide.
e) Sulfuric acid and aluminum hydroxide.
2.
Calculate the concentration of a solution of KOH if 140.0 mL of the base is needed to neutralize 22.5
mL of 0.175 mol/L acid HNO3.
3.
Determine the volume of 0.750 mol/L LiOH required to neutralize 56.0 mL of 0.350 mol/L H2SO4.
4.
What volume of 0.240 mol/L H2SO4 can be neutralized by 50.0 mL of 0.360 M NaOH?
5.
Calculate the concentration of the acid, if 25.0 mL of H3PO4 is required to neutralize 19.0 mL of 0.830
mol/L KOH.
6.
What volume of 0.100 mol/L HCl is required to just neutralize 10.0 g of solid NaOH?
7.
What volume of 0.250 mol/L nitric acid is needed to just neutralize 25.0 g of magnesium hydroxide?
8.
What mass of calcium hydroxide is needed to just neutralize 250.0 mL of 0.100 mol/L HCl? Assume the
volume does not change.
2. 0.0281 mol/L 3. 52.3 mL 4. 37.5 mL 5. 0.210 mol/L 6. 2.50 L 7. 3.43 L 8. 0.926 g
16
Mr. Storie
40S Chemistry
Student– Acid and bases Unit
Titrations Worksheet
1. I titrated 3.5 mL of NaOH with 25 mL of 5.0 x 10-2 M HCl. Find the concentration of this base and
determine its pH. (0.36 M, 13.6)
2. If it took me 25.4 mL of 5.0 mM HCl to titrate 50.0 mL of a strong basic solution with unknown
concentration, what were the concentration and pH of the basic solution? (2.54 x 10-3 M, 11.4)
3. How many mL of 0.010 M NaOH will be required to neutralize 10.0 mL of HCl with a pH of 1.0?
(100 mL)
17
Mr. Storie
40S Chemistry
ANSWER THE FOLLOWING QUESTIONS ON TITRATIONS:
Student– Acid and bases Unit
1. A sample of vinegar is titrated with a 0.990 mol/L sodium hydroxide solution, to determine the
concentration of acetic acid. Given the following data,
a. Calculate the concentration of acetic acid in the vinegar for each trial.
b. Calculate the average concentration over the three trials. (0.830 mol/L)
2. The neutralization of 0.900 g of an unknown monoprotic solid acid required 30.00 mL of 0.150 mol/L
NaOH. Calculate the molar mass of the acid. (200 g/mol)
3. A sample of a monoprotic acid (molar mass 97.09 g/mol) is dissolved in enough water to make 250.0 mL of
solution. A 12.00 mL aliquot of the acid solution is titrated with a 0.0850 mol/L solution of NaOH. If 17.55
mL is required to reach the endpoint, what is the mass of the original sample? (3.02 g)
18
Mr. Storie
40S Chemistry
Student– Acid and bases Unit
4. Aspirin™ tablets are made of acetylsalicylic acid (ASA) and fillers. An Aspirin™ tablet with mass of 0.500
g was powdered, suspended in water and titrated with 0.150 mol/L NaOH solution. If it requires 11.80 mL
of NaOH solution to reach the endpoint, how much ASA does the tablet contain? ASA is a monoprotic acid
with a formula of C9H8O4. (0.319 g)
5. A student pipetted 25.0 mL of an aqueous solution of an unknown monoprotic acid into an Erlenmeyer flask,
added about 25 mL of water and titrated with a standard 0.0985 mol/L sodium hydroxide solution. The pH
was measured after each addition. The graph below shows the graph obtained.
Use the graph to answer the following questions.
a. What was the concentration of the unknown acid? (0.104 mol/L)
b. What would be a suitable range for an indicator to change colour for this titration?
19
Mr. Storie
40S Chemistry
Student– Acid and bases Unit
Acids and Bases Review
1. Explain how the Lewis definition of a base is different from that of the Arrhenius definition of a base. Are
Arrhenius bases also bases under the Lewis definition? Explain.
2. Determine the type of reaction occurring below. If possible label the conjugate acid-base pair in the
appropriate place (Think about what is taking place in the reaction).
a. H2SO4 + H2O  HSO3-1 + H3O
b. Ca(OH)2 + 2 HNO3  Ca(NO3)2 + 2 H2O
c. NaCl  Na+ + Cl-
3. What’s the pH of a 3.3 x 10-5 M NaOH solution?
4. Find the pH of a 0.0050 M acetic acid solution. Ka = 1.8 x 10-5 (3.5)
5. What is the pH of a solution that contains 2.4 x 10-5 moles of hydrobromic acid in 0.50 L of water? (4.3)
20
Mr. Storie
40S Chemistry
Student– Acid and bases Unit
6. What is the pH of a solution that contains 25 moles of nitric acid dissolved in 5000 L of water? (2.30)
7. In a few steps, describe how you would titrate a base of unknown concentration with an acid with
concentration of 1 M.
8.
I did a titration where it took 50 mL of 0.1 M hydrochloric acid to neutralize 500 mL of a base with
unknown concentration. Using this information, what was the concentration of the base? (0.01 M)
9. I did a titration where it took 25 mL of 5 M NaOH to neutralize 1000 mL of an acid with unknown
concentration. Using this information, what was the concentration of acid? (0.125 M)
10. If it takes 560 mL of 0.0050 M NaOH to neutralize 100.0 mL of H2SO4 solution with unknown
concentration, what was the original pH of the H2SO4 solution? ( 1.9)
21