Part 01 - Assignment: Introduction to Acids &Bases

Transcription

1 Part 01 - Assignment: Introduction to Acids &Bases Classify the following acids are monoprotic, diprotic, or triprotic by writing M, D, or T, respectively. 1. HCl 2. HClO4 3. H3As 4. H2SO4 5. H2S 6. H3PO4 7. HNO3 8. H2CO3 Are the following substances amphiprotic? Write YES or NO. 9. H2O 10. HCl 11. HI 12. NaOH 13. H2PO HPO4 15. H3PO4 16. H2CO3 17. HCO3 18. H2SO4 19. HSO4 20. SO4 2 Write an equation for the ionization of each of the following acids in water solution. 21. HCl 22. H2CO3 Write an equation for the dissociation of each of the following in water solution. 23. NaOH 24. Ca(OH)2 Answer the following questions. 25. A Bronsted acid is a substance that donates a proton to another substance. Is a proton removed from the nucleus of one of the atoms in an acid? If yes, how does this happen since it is not a nuclear reaction? If no, how does the substance donate a proton? 26. What is the range for the ph scale? Select the answer choice that best answers the question or completes the statement and circle that letter choice. 27. In the reaction NH3(g) + HCl(g) NH4Cl(s), the NH3 acts as... (a) an electron acceptor. (b) a proton acceptor. (c) a proton donor. (d) a reducing agent. page 1 of 2

2 Part 01 - Assignment: Introduction to Acids &Bases 28. In the reaction S 2 + HSO4 HS + SO4 2, the two Brønsted-Lowry bases are... (a) HSO4 and SO4 2 (b) S 2 and HSO4 (c) S 2 and HSO4 (d) S 2 and HS 29. Which of the following cannot be a Brønsted-Lowry acid? (a) H2CO3 (b) NH3 (c) SO4 2 (d) NH Which one of the following is a Lewis acid, but NOT a Brønsted acids? (a) HCl (b) BBr3 (c) NH3 (d) KOH (e) CH4 31. Which of the following species is considered an acid according to the Lewis theory but not according to the Arrhenius or Brønsted-Lowry theories? (a) a proton donoe (b) a proton acceptor (c) HCl (d) an electron pair donor 32. What group of atoms is present in all carboxylic acids? (a) -CH3 (b) -OH2 (c) -NH3 (d) -COOH (e) an electron pair acceptor 33. What feature must any molecule or ion have in order to act as a Lewis base? (a) at least one atom with an unshared pair of e (b) at least atom with an electron deficiency (c) must have a positive charge (d) must have a negative charge 34. Given than HClO4 is a strong acid, how is the basicity (alkalinity) of ClO4 classified? (a) strong base (b) weak base (c) negligible basicity (d) never a base page 2 of 2

3 Part 02 - Assignment: Conjugate Acid-Base Pairs & K W Show the conjugate acid base pairs for the following reactions. Write A and B on the reactant side above the appropriate substance. Then write, CA and CB on the product side above the appropriate substance. 1. CO3 2 + H2O HCO3 + OH 2. HCN + H2O H3O + + CN 3. H2S + (CH3)2NH (CH3)2NH2 + + HS 4. HF + H2O H3O + + F 5. HC2H3O2 + H2O H3O + + C2H3O2 6. HSO4 + HPO4 2 SO4 2 + H2PO4 7. N2H4 + H2O N2H5 + + OH 8. NH2OH + HCl NH3OH + + Cl 9. NH2 + N2H4 NH3 + N2H3 10. HNO3 + H2SO4 H3SO4 + + NO3 Select the answer choice that best answers the question or completes the statement and circle that letter choice. 11. Compared to its conjugate base, a Brønsted-Lowry acid possesses... (a) one more proton. (b) the same number of protons (c) one less proton. 12. As conjugate acid strength decreases, the strength of conjugate bases... (a) decreases. (b) increases. (c) remains the same. 13. Which Bronsted-Lowry acid has a conjugate base that that amphoteric properties? (a) HCl (b) NHO3 (c) H3O + (d) HSO4 page 1 of 2

4 Part 02 - Assignment: Conjugate Acid-Base Pairs & K W 14. Which reaction illustrates amphoterism? (a) H2O + H2O H3O + + OH (c) NaCl Na + + Cl (b) HCl + H2O H3O + + Cl (d) NaOH Na + + OH 15. The hydronium ion, H3O + is a water molecule that has... (a) lost a proton. (b) gained a proton. (c) gained a neutron. (d) gained a electron pair. 16. In the forward reaction of this equilibrium, which substance acts as the Bronsted-Lowry base? H2S(aq) + CH3NH2(aq) x HS (aq) + CH3NH3 + (aq) (a) both substances act as bases (b) neither act as a base (c) H2S(aq) (d) CH3NH2(aq) (e) gained an electron. 17. Which of the following is amphoteric? (a) SO4 2 (b) HCl (c) H2O (d) NH4 + (e) none listed 18. Which of the following is NOT a conjugate acid/base pair? (a) SO4 2 /HSO4 (b) HC2H3O2/C2H3O2 (c) HO /H3O + (d) H2SO3/HSO3 page 2 of 2

5 Part 03 - Assignment: ph, poh, K w - Acid Concentrations Supply answers for the following questions. Show all work, set-ups, etc. Use additional paper if necessary to show all work. 1. Calculate the ph of the solutions with these concentrations: (a) M H3O + /L (b) mol OH /L (c) 1.62x10 5 mol OH /L 2. Calculate the poh of the solutions with these concentrations: (a) 4.57x10 6 mol OH /L (b) 5.75x10 2 mol H3O + 3. Calculate the [H3O + ] of the following solutions. (a) ph = 3.72 (b) poh = Calculate the [OH ] of the following solutions. (a) poh = (b) ph = Calculate the (i) ph and the (ii) poh of solutions having the following concentrations. Assume 100% ionization. (a) M H2SO4 page 1 of 2

6 Part 03 - Assignment: ph, poh, K w - Acid Concentrations (b) M Ca(OH)2 6. The ph of human blood is 7.4. What is the [H3O + ]? 7. (i) What is the [H3O + ] in a red ripe tomato that has a ph of 4.2? (ii) What is the poh? (iii) What is the [OH - ]? 8. Find the [H3O + ] and the ph of the following solutions: (a) 0.325M H2SO4 (assume 100% ionization) (b) M Ca(OH)2 9. Find the [OH - ] and the ph of the following solutions: (a) M Mg(OH)2 (b) 1.25M H3PO4 10. If the poh for a solution is 3.00, what is the ph? Is the solution acidic or basic? (a) ph = 17.00; basic because ph > 7 (b) ph = 11.00; basic because ph > 7 (c) ph = 3.00; acidic because ph < 7 (d) ph cannot be determined without [H + ]. 11. Is it possible for a solution to have a negative ph? If so, would that ph signify an acidic or a alkaline solution? (a) No, the ph range is (b) No, the definition of ph does not permit a ( ) value. (c) Yes, for any solution with a concentration of base greater than 1M. (d) Yes, for any solution with a concentration of acid greater than 1M. 12. Which solution has a higher ph, a 0.001M solution of NaOH or a 0.001M solution of Ba(OH)2? (a) 0.001M Ba(OH)2 has higher ph 0.001M NaOH has a high ph (c) Both solutions have the same ph since both have the same concentration. page 2 of 2

7 Part 04 - Assignment: Titration & Neutralization Answer the following questions; show all work, set-ups, units, etc. Use additional paper if necessary ml of M HCl is exactly neutralized by 50.0 ml of Ca(OH)2 solution. Calculate the concentration of the Ca(OH)2 solution ml of M H2SO4 is exactly neutralized by 50.0 ml NaOH solution. Calculate the NaOH concentration. 3. How many ml of M HCl are required to react with 10.0 g of solid calcium hydroxide? ml of NaOH solution are required to exactly neutralize 1.50 g of a solid acid having a molar mass of 180. g/ mol. The acid has two ionizable hydrogen. Find the concentration of the NaOH solution g of an unknown acid, H2X, having two ionizable hydrogens, is exactly neutralized by 42.5 ml of M NaOH solution. Calculate the molar mass of the acid, H2X. page 1 of 2

8 Part 04 - Assignment: Titration & Neutralization 6. How many grams of barium hydroxide would be needed to completely neutralize 30.0 ml of M phosphoric acid? 7. Leland reads the initial volume of the 0.125M KOH buret as 8.32mL. He adds KOH to his flask until the buret reads 31.26mL. The initial volume of Leland s H2SO4 buret is 0.00 ml. He titrates the acid into the base until the system reaches neutral and the final reading on the acid buret it 19.48mL. What is the concentration of the sulfuric in Leland s buret. 8. Anushka reads the initial volume of the M HCH3COO buret as 2.28 ml. She adds this acid to her flask until a volume of 26.95mL are added. The initial volume of Anushka s Ca(OH)2 buret is 10.52mL. She titrates the base into the acid until the system reaches neutral and the final reading on the base buret is 33.74mL. What is the concentration of the acetic acid in Anushka s buret? For the following, select and circle the letter choice of the answer that best answers the question or completes the statement. 9. Equal volumes of 0.100M solutions of KOH and HNO3are mixed. The ph of the resulting solution is closest to... (a) 1. (b) 7. (c) 3. (d) As excess HCl solution is added to a beaker containing NaOH solution, the ph of the mixture in the beaker... (a) increases to 7 and stops. (b) decreases to 7 and stops. (c) increases continuously past 7. (d) decreases continuously past 7. page 2 of 2

9 Part 05 - Assignment: Hydrolysis of Salts Predict the hydrolysis effect in a solution of each of the following salts. For answer, write acidic, basic, or neutral. Also indicate the ph (<7, >7, or =7) of the resulting solution and list the acid and base that react to produce the result indicated by the problem. A/B/N ph Acid + Base 1. Na3PO4 2. Na2SO4 3. K2C2O4 4. NH4Cl 5. FeCl3 6. NH4NO3 7. Ca(NO3)2 8. KC2H3O2 9. Mg(C2H3O2)2 10. K2CO3 Select and circle the letter of the answer choice that best answers the question or completes the statement. 11. In which of the following pairs of acids are both members of the pair strong acids? (a) H3PO4 & H2SO4 (b) HCl & HNO3 (c) H2CO3 & HBr (d) HC2H3O2 & HI 12. In which of the following pairs of acids are both members of the pair polyprotic? (a) H2SO4 & HC2H3O2 (b) HNO3 ^ H2C4H6O6 (c) HC2H3O2 & H3C6H5O7 (d) H3PO4 & H2C4H4O7 13. Which of the following is produced in the first step of the dissociation of the acid H3PO4? (a) H3PO4 (b) H2PO4 (c) HPO4 2 (d) PO4 3 page 1 of 2

10 Part 05 - Assignment: Hydrolysis of Salts 14. If the ph of a solution increases from 4.0 to 6.0, the hydronium ion concentration... (a) increases by a factor of 1.5. (b) increases by a factor of 100. (c) decreases by a factor of 1.5. (d) decreases by a factor of In which of the following pairs of salts will both members of the pair hydrolyze in water to give solutions that are basic? (a) NaCl & NaCN (b) NH4Cl & NH4NO3 (c) KC2H3O2 & KCN (d) NaNO3 & Na2SO4 16. If the ph of a solution of a salt is 5.0, the salt must be one which could be formed from the neutralization of... (a) a strong acid and a string base. (b) a weak acid and a strong base. (c) a strong acid and a weak base. (d) HCl and NaOH. page 2 of 2

11 Part 06 - Assignment: Acids, Bases, & Equilibrium Answer the following questions on a separate sheet of paper. Show all work, set-ups, units, etc. 1. Calculate the (a) ph and (b) Ka of a M acetic acid solution if 1.34% of the CH3COOH molecules in this solution have ionized to form product ions. 2. Calculate (a) the ph and (b) the percent dissociation of a M solution of HCN. Ka = 4.90 x A M solution of acetic acid is only partially ionized. Using a measure of ph, the [H3O + ] is determined to be 1.34x10 3 M. What is the acid ionization constant, Ka? 4. A M solution of a weak acid, H2X, is only partially ionized. The [H3O + ] was found to be 4.58 x 10 4 M. Find the dissociation constant for this acid. 5. Calculate the acid dissociation constant of a weak monoprotic acid if a M solution of this acid gives a hydronium ion concentration of M. 6. Determine the (a) [H3O + ], (b) [OH ], (c) ph, and (d) poh of a 1.00 x 10 4 M HCN solution that undergoes 3.52% ionization. 7. Determine the (a) [H3O + ], (b) [OH ], (c) ph, and (d) poh of a 1.60 x 10 3 M oxalic acid solution that undergoes 0.166% ionization. H2C2O4 + H2O H3O + + HC2O4 8. What would be the ionization constant for a weak acid at 25 o C if a M solution of this acid is ionized to the extent of 3.42%? 9. A M solution of a weak acid, HX, has a ph of Calculate the Ka of HX. 10. A weak acid, HX, has Ka = 5.00 x A certain solution of this acid has ph = Calculate the concentration of the acid in this solution. 11. Nitrous acid, HNO2, has Ka of 5.15 x (a) Calculate the ph of M HNO2. (b) Calculate the percent ionization of M HNO A M solution of acid HX is 7.50% ionized. Calculate the Ka and the ph of this acid. Select the answer choice that best completes the statement or answers the question and circle its letter. 13. Which of the following is true regarding the Ka values of a diprotic acid? (a) Ka1 < Ka2 (b) Ka1 = Ka2 (c) Ka1 > Ka2 (d) cannot be determined 14. What is the pure Kw f pure water at 50 o C if the ph is 6.630? 2 H2O(l) H3O + (aq) + OH (aq) (a) 1.00x10 14 (b) 2.34x10 7 (c) 5.50x10-14 (d) 2.13x10 14 page 1 of 2

12 Part 06 - Assignment: Acids, Bases, & Equilibrium 15. Why can we generally assume that the equilibrium concentration of a weak acid equals its initial concentration? (A) Because Ka for weak acids is slightly less than 1 and therefore, the extent of ionization is very small and can be neglected. (B) Because most weak acids of low to moderate concentration undergo very little ionization, often less than 1% in solution, and thus the extent of ionization can be neglected. (C) Because most weak acids of high of low concentration will form minimal conjugate base and thus the extent of ionization can be ignored. (D) Because for weak acid dissociating in a solution, a weak acid molecule is formed with minimal conjugate base forming and thus the extent of ionization can be neglected. 16. Which of the following acids has the largest Ka? Acid I Acid II Acid III (a) Acid I (b) Acid II (c) Acid III (d) All have the same Ka page 2 of 2