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Acids & Bases Test [print-friendly version]
1. Show using an equation the ionization of water. Write the equilibrium expression for Kw. What is the value of this constant at 25oC?
2. The [H+] of a dilute hydrochloric acid solution is 0.001M. What is the [OH-] of the solution?
3. The [OH-] of a sodium hydroxide solution is 1 x 10-2 M. What is the [H+] of the solution?
4. Calculate the [H+] and the [OH-] for a solution in which 0.96g of lithium hydroxide is dissolved in enough water to make 1500 mL of solution.
5. Suppose 1.00 x 10-2 mole of KOH and 1.00 x 10-4 mole of HCl are both added to a litre of water. Calculate the final [H+] and [OH-] of the resultant solution. (Ignore volumes occupied by the added acid and base).
6. Explain, using Le Chatelier's principle, what happens to the [H+] of a 1.0 M solution of acetic acid when one drop of 1.0 M NaOH is added.
7. 50 mL of 0.1 M HCl is added to 50 mL of 1.0 M NaOH. Find the[H+] and [OH-] of the resultant solution.
8. Find the [H+]and [OH-] of a solution made by mixing 25 mL of 0.100M NaOH and 75 mL of 0.01 M HCl.
9. 30 mL of 0.0200 M NaOH solution is added to 70 mL of 0.0100 M HCl solution. Calculate the [H+]and [OH-] of the resulting solution.
10. 10 mL of 0.0100 M HCl is titrated with a base of unknown concentration. If 40.0 mL of the base is needed to reach the end-point, what is the concentration of the base?
11. Exactly 12 mL of 0.0240 M NaOH is required to neutralize 20.0 mL of HCl solution. What is the concentration of the HCl?
12. To 20.0 mL of 0.200 M nitric acid (HNO3) is added successive amounts of a base of unknown concentration. Neutrality is reached after the addition of 40.0 mL of the base. (a) What was the [OH-] of the original base solution? (Assume that it was 100% ionized i.e. a strong base.) (b) Calculate the [H+]and [OH-] of the solution when exactly 10.0 mL of the base had been added during the titration. (c) Calculate the [H+]and [OH-] of the solution when exactly 20.0 mL of the base had been added during the titration.
13. What volume of 0.200 M NaOH solution will be needed to neutralize each of the following: (a) 10.0 mL of 0.10 M HCl (b) 5.0 mL of 0.010 M HNO3 (c)15.0 mL of 0.050 M HCl
14. A solution has a pH of 12. (a) Calculate the [H+] of the solution. (b) Calculate the [OH-] of the solution. (c) Predict the result of adding one drop of phenolphthalein indicator to the solution. (d) Identify the solution as acidic or basic.
15. Calculate the pH of a 0.0010 M HCl solution?
16. What is the pH of a solution that contains 1 x 10-9 moles per litre of OH- ions?
17. Solution X has a pH of 2. Solution Y has a pH of 4. On the basis of this information which of the following is true? (a) The [H+] of X is half that of Y. (b) The [H+] of X is twice that of Y. (c) The [H+] of X is 100 times that of Y. (d) The [H+] of X is 1/100 that of Y.
18. Write the chemical equation to show that a solution of H2SeO3 is acidic. Write the Ka expression for this reaction.
19. Using Le Chatelier's principle, explain the effects on the following concentrations that result from adding one drop of 1 M HCl to a 1 M CH3COOH solution. (Remember that acetic acid is a weak acid.) (a) [H+] (b) [CH3COOH] (c) [CH3COO-] (d) [OH-]
20. Use Le Chatelier's principle to explain the effects on the following concentrations that result from adding one drop of 1 M HCl to a 1 M nitrous acid solution (HNO2). (a) [H+] (b) [HNO2] (c) [NO2-] (d) [OH-]
21. List the following acids in order of increasing strengths (weakest to strongest); nitrous acid, iron (III) ion, hydrogen peroxide, acetic acid, and the hydrogen sulfite ion. Give a quantitative reason for your ranking.
22. The pH of a 0.1 M solution of cyanic acid (HCNO) is found to be 3. (a) Write the equation for the ionization of cyanic acid. (b) Write the Ka expression for this reaction. (c) Calculate the value of Ka for this reaction.
23. The Ka for hydroiodous acid (HOI) is approximately 2.5 x 10-11. What would you expect the [H+] of a 0.010 M solution of this acid to be?
24. Use Le Chatelier's principle to predict the effect on the [H+] of adding sodium formate (HCOONa) to a solution of formic acid (HCOOH). Calculate the [H+] in 1.00 L of a solution in which there have been dissolved 0.20 mole of formic acid and 0.40 mole of sodium formate. The value of Ka for formic acid is 1.8 x 10-4. State any assumptions made in your calculations and show whether these assumptions are valid.
25. Calculate the [H+] in 1.00 L of a solution in which there have been dissolved 0.10 mole of hydrofluoric acid (HF) and 0.10 mole of sodium fluoride. The value of Ka for hydrofluoric acid is 6.7 x 10-4.
26. (a) Write the equation that shows the weak acid-weak base reaction between hydrogen telluride (H2Te) and the sulfide ion (S2-). (b) Label each reactant as either a Lowry-Bronsted acid or base. (c) Use the respective Ka values of the two acids to identify the stronger acid and then predict whether the equilibrium favours the reactants or the products.
27. (a) Write the equation that shows the weak acid-weak base reaction between benzoic acid (C6H5COOH) and the dihydrogenphosphate ion (H2PO4-). (b) Label each reactant as either a Lowry-Bronsted acid or base. (c) Use the respective Ka values of the two acids to identify the stronger acid and then predict whether the equilibrium favours the reactants or the products.
28. Complete reaction equations for each of the following acid-base pairs. Label each reactant as either an acid or a base. For each reaction predict whether the reactants or products are favoured. (a) HBr(aq) + SO42-(aq) (b) H3PO4(aq) + NO3-(aq) (c) NH4+(aq) + S2-(aq)
29. 2.00 g of solid sodium hydroxide pellets are dissolved in water and made up to 500 mL of solution. State (a) the entities (species) present in the solution. (b) the [OH-] (c) the [H+] or the [H3O+] (d) the pH of the solution.
30. 2.0 mL of 14 M HNO3 is made up to 400 mL of solution with water. Calculate (a) the molarity of the resulting solution (b) the H+] or the [H3O+] of the solution. (c) the pH of the solution. (d) the mass of solid KOH which would have to be added to the 400 mL of this solution to increase the pH to 7.0.
31. Calculate the pH of solutions in which the [H+] (or [H3O+]) is as follows (a) 1 x 10-4 mol L-1 (b) 0.03 mol L-1 (c) 5.3 x 10-5
32. Calculate the [H+] and [OH-] in solutions with the following pH. (a) 8.0 (b) 0.2 (c) 12.3
33. Calculate the pKa of the following acids whose Ka values are given. (pKa = -log Ka) (a) Ka(HSO3-) = 1 x 10-7 (b) Ka(HCOOH) = 2 x 10-4 (c) Ka(H3PO4) = 7.5 x 10-3
34. Calculate the Ka of the following acids whose pKa values are as follows. (a) pKa (HN3) = 4.72 (b) pKa (HCN) = 9.32 (c) pKa (H3AsO4) = 2.22
35. State the pH of each of the following solutions of hydrochloric acid: (a) a 0.1 M solution (b) a 0.01 M solution (c) a 0.001 M solution. (d) a 0.00025 M solution.
36. Given the Ka(HCO3-) = 6 x 10-11 and Kb (HCO3-) = 3.33 x 10-8, calculate the equilibrium constants for the reactions: (a) 2 HCO3- H2CO3 + CO32- (b) H2CO3 + 2H2O 2H3O+ + CO32-
37. Formic acid (HCOOH) and ammonia are both weak electrolytes since both hydrolyze to only a slight extent in water as indicated by Ka(HCOOH) = 2 x 10-4 and Kb (NH3) = 1.8 x 10-5. (a) Calculate the equilibrium constant for the reaction HCOOC + NH3 HCOO- + NH4+ Remembering that Kw = 1 x 10-14 If equal volumes of 0.10 M HCOOH and 0.1 m NH3 are mixed: (b) Decide whether the solution formed would be a good electrical conductor. (c) state qualitatively the approximate concentrations of each of the following entities which exist in the resulting solution. HCOOH, HCOO-, NH3,, NH+, NH4+, H3O+, and OH-.
38. Hydrazoic aci, HN3 is a weak monoprotic acid which hydrolyzes in water according to the equation: HN3 + H2O H3O+ + N3- The pKa of this acid is 4.72 (a) Calculate the [H3O+] in a 0.1 M solution of the acid, and hence determine the approximate concentrations of each of the following species in the solution: HN3, N3-, and OH-. (b) Estimate the percentage hydrolysis of the acid. (c) Calculate the pH of the solution.
39. Find the [H3O+] and the pH in: (a) a solution of 0.2 M NaOH (b) a solution of 0.5 M HCl (c) a mixture of 40 mL of (a) and 25 mL of (b) (d) The solution formed when 0.5 g of solid Na Oh is added to solution (c)
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