Skill Practice 48
Name: ______________________________
Date: _______________
Hour: _____
1. A certain substance in solution is known to increase the concentration of H3O+. Is this substance
an acid or a base?
Acid
2. Given the following reaction, identify the Arrhenius acid and describe why the substance you
chose is an Arrhenius acid.
H2SO4 Æ HSO4- + H+
It is an acid because it increases the concentration of H+ in solution.
3. How do the Bronsted-Lowry definitions and the Arrhenius definitions differ?
Bronsted-Lowry: an acid donates a proton (H+)
Arrhenius: an acid increases the concentration of H+ in solution.
4. Describe the difference between a weak and a strong acid.
Strong acids dissociate completely, but weak acids only dissociate partially.
5. In each of the following reactions identify an acid (if there is one) and then specify whether it is
an acid according to the Arrhenius definitions or the Bronsted-Lowry definitions or both.
a) H2CO3 + CN- Æ HCN + HCO3-
Bronsted-Lowry
b) F- + HSO4- Æ HF + SO42-
Bronsted-Lowry
c) HSO4- + H2O Æ H3O+ + SO42-
Both
6. What is the conjugate base of HCN?
CN-
© 2004 by Jason Neil. All rights reserved.
Skill Practice 49
Name: ______________________________
Date: _______________
Hour: _____
1. What is the pH of a 0.034 M solution of HNO3?
1.47
3. Calculate the pH of a 0.0105 M solution of NaOH?
12.0212
4. a) Calculate the pH of a 0.025 M solution of HNO3.
1.60
b) What is the pOH of this solution?
12.40
5. Calculate [H+], [OH-], pOH and the pH for a 0.0015 M solution of HCl.
[H+] = 0.0015 M
[OH-] = 6.67x10-12 M
pOH = 11.18
pH = 2.82
6. Calculate [H+], [OH-], pOH and the pH for a 0.00024 M solution of sodium hydroxide, NaOH.
[H+] = 4.17x10-11 M
[OH-] = 0.00024 M
pOH = 3.62
pH = 10.38
© 2004 by Jason Neil. All rights reserved.
Skill Practice 50
Name: ______________________________
Date: _______________
Hour: _____
1. What is the pH of a 0.34 M solution of HNO3?
0.47
2. What is the pH of a 0.34 M solution of benzoic acid (Ka=6.3x10-5) ?
2.33
3. Compare the concentrations and pH of each solution in questions 1 and 2. Why are weak acids
called weak? What is the relationship between a weak acid’s Ka value and the pH?
Weak acids do not dissociate completely. The larger the Ka, the lower the pH.
4. Acetic acid (HC2H3O2) has an ionization constant of 1.7x10-5. What is the Kb for C2H3O2- ?
5.88x10-10
5. What is the pH of a 0.16 M solution of acetic acid?
2.78
6. A 0.25 M solution of an unknown acid has a pH of 2.5. What is the Ka of the acid?
4.05x10-5
7. Ammonia is a weak base with Kb = 1.8x10-5. What is the pH of a 0.5 M solution of NH3?
11.48
8. A 0.045 M solution of a certain unknown base has a pH of 9.7. What is the Kb for this base?
5.58x10-8
© 2004 by Jason Neil. All rights reserved.
Skill Practice 52
Name: ______________________________
Date: _______________
Hour: _____
1. Indicate whether the following salts will result in an acidic (A), basic (B), or neutral (N) pH
when dissolved in water.
__A__ a) NH4Cl
__N__ b) NaCl
__B__ e) Na2C2H3O2
__A__ f) NH4Cl __N__ g) MgCl2
__B__ c) Mg(CN)2
__B__ d) CaF2
__N__ h) Ca(NO3)2
2. What is the pH of a solution formed by dissolving 25.8 g of ammonium chloride (NH4Cl) in
1.5 L of water?
4.87
3. A solution was made by adding acetic acid and a salt to water. The concentration of acetic
acid in the solution was 0.5 M. The pH of the solution was found to be 3.3. Was the salt
calcium chloride or sodium acetate? Explain.
The pH of 0.5 M acetic acid is 2.5. Since the solution with the salt has a pH of 3.3, the
salt must be basic. Sodium acetate if basic; calcium chloride would not affect the pH.
4. Calculate the pH of a 0.045 M solution of sodium benzoate. (Benzoate is the anion formed
from benzoic acid, which has a Ka of 6.3x10-5.)
8.43
5. What effect on the pH does NH4NO3 have when it is added to a solution of ammonia in
water?
It lowers the pH.
6. Calculate the pH of a 0.035 M solution of sodium acetate.
5.34
7. Calculate the pH of a 0.00046 M solution of NH4Cl.
6.30
© 2004 by Jason Neil. All rights reserved.