+ H + H 2 PO 4. H + + HAsO In the reaction, HClO 3 + N 2 H 4 ClO 3 + N 2 H + 5, which two species are both bases? Acid Base conj base conj acid

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1 Chapter 7 AcidBase 1. The conjugate acid of HPO 4 2 is a. H 2 PO 4 b. H 3 PO 4 c. PO 4 3 d. PO 4 2 * e. H 2 PO 4 HPO 4 2 is base (accept H ) HPO 4 2 H H 2 PO 4 2. The conjugate base of H 2 AsO 4 is a. H 2 AsO 4 b. H 3 AsO 4 c. HAsO 4 * d. HAsO 4 2 e. AsO 4 3 H 2 AsO 4 is acid (donate H ) H 2 AsO 4 H HAsO In the reaction, HClO 3 N 2 H 4 ClO 3 N 2 H 5, which species are an acidbase pair? Acid Base conj base conj acid a. HClO 3, N 2 H 4 b. N 2 H 4, ClO 3 c. HClO 3, N 2 H 5 * d. N 2 H 4, N 2 H 5 e. ClO 3, N 2 H 5 4. In the reaction, HClO 3 N 2 H 4 ClO 3 N 2 H 5, which two species are both bases? Acid Base conj base conj acid a. HClO 3, N 2 H 4 b. HClO 3, ClO 3 c. HClO 3, N 2 H 5 d. N 2 H 4, N 2 H 5 * e. ClO 3, N 2 H 4 5. In the reaction, HSO 4 Acid a. HSO 4, HS * b. HSO 4, H 2 S c. HS, H 2 S d. HS 2, SO 4 2 e. H 2 S, SO 4 HS H 2 S SO 2 4, which two species are both acids? Base conj base conj acid 1

2 6. For the system NH 2 OH CH 3 NH 3 CH 3 NH 2 NH 3 OH 2 Base Acid conj base conj acid the position of the equilibrium lies to the left. Which is the strongest acid in the system? a. NH 2 OH b. CH 3 NH 3 c. CH 3 NH 2 * d. NH 3 OH 2 e. NH 2 OH and CH 3 NH 3 are equal in acid strength, and are the strongest acids in the system Direction always from Strong weak Equilibrium lies to the left, this mean weak on left or strong on wright 7. If the OH ion concentration in an aqueous solution at 25.0 C is measured as 3.4 x 10 3 M, what is the ph? a b c * d e [OH ]=3.4 x 10 3 [H ]= 1 x / [OH ] = 1 x / 3.4 x 10 3 = 2.94x ph = log [H ]= log 2.94x = The ph of a solution is measured to be What are the values of [H 3 O ] and [OH ] for this solution? a. [H 3 O ] = 4.0 x 10 11, [OH ] = 4.0 x 10 3 b. [H 3 O ] = 2.5 x 10 4, [OH ] = 4.0 x c. [H 3 O ] = 1.0 x 10 10, [OH ] = 3.6 x 10 4 * d. [H 3 O ] = 4.0 x 10 11, [OH ] = 2.5 x 10 4 e. [H 3 O ] = 9.6 x 10 2, [OH ] = 2.8 x 10 1 ph=10.4 [H ]= 10 ph = (OR Shift log 10.4) = 4.0 x [OH ] 1 x / 4.0 x = 2.5 x If the OH ion concentration in an aqueous solution at 25.0 C is 6.6 x 10 4 M, what is the molarity of the H ion? a. 1.5 x 10 1 M b. 1.5 x 10 4 M c. 6.6 x M * d. 1.5 x M 2

3 e. 6.6 x M [OH ] = 6.6 x 10 4 [H ]= 1 x / [OH ] = 1 x / 6.6 x 10 4 = 1.5 x If the H ion concentration in an aqueous solution at 25.0 C has a value of M, what is the poh of the solution? a b c * d e [H ] = [OH ]= 1 x / [H ] = 1 x / 0.100= 1 x ph = log [H ]= log 1 x = If the H ion concentration in an aqueous solution at 25.0 C has a value of M, then what is the ph of the solution? a b * c d e [H ] = ph = log [H ]= log 0.1 = If the H ion concentration in an aqueous solution at 25.0 C is measured as 6.6 x 10 4 M, what is the ph? a * b c d e [H ] = 6.6 x 10 4 ph = log [H ]= log 6.6 x 10 4 = Calculate the ph of a beer in which the hydrogen ion concentration is 3.9 x 10 5 M. * a. 4.4 b. 3.9 c d. 5.0 e

4 [H ] = 3.9 x 10 5 ph = log [H ]= log 3.9 x 10 5 = Calculate the ph of a M solution of Ca(OH) 2 whose temperature is 25.0 C. a b c * d e [Ca(OH) 2 ]= [OH ]= 2 x = 0.04 [H ] = 1 x / 0.04= 2.5 x ph = log [H ]= log 2.5 x = Given 0.01 M solutions of each of the following bases, which solution would have the highest ph? a. Aniline (C 6 H 5 NH 2 ), K b = 3.9 x ph= 8.3 * b. Dimethylamine ((CH 3 ) 2 NH), K b = 5.1 x 10 4 ph= c. Hydrazine (N 2 H 4 ), K b = 1.3 x 10 6 ph= d. Methylamine (CH 3 NH 2 ), K b = 4.4 x 10 4 ph= e. Pyridine (C 5 H 5 N), K b = 1.7 x 10 9 ph= 8.6 All weak bases a) [OH ]= (Kb x C o ) =(Ka x C o ) 1/2 = (3.9 x x 0.01) =1.97 x 10 6 poh=log 1.97 x 10 6 =5.7 ph= 14 poh = 8.3 Repeat for all b to e Conclusion: you can find the highest K b is highest [OH ] and the most basic solution which is the highest ph 16. The ionization constant, K a, for macnic acid is 5.0 x What is the pk a of this acid? a * b c d e pk a = log K a = log 5.0 x 10 5 = Formic acid, HCO 2 H, has an ionization constant with the value: K a = Calculate the value of pk b for the conjugate base of formic acid. a b c

5 * d e K a x K b = 1 x K b = 1 x / = 5.68 x pk b = log K b = log 5.68 x = A M solution of an acid, HA, has a ph = What is the value of the ionization constant, K a for this acid? a * b c d e ph = 2.00 [H ] = 10 ph = 10 2 [H ] = (Ka x C o ) = (Ka x C o ) 1/2 = (K a x 0.1) [H ] 2 = (Ka x C o ) = (K a x 0.1) (10 2 ) 2 = K a x 0.1 K a = 10 4 / 0.1= A M solution of an acid, HQ, has a ph = What is the value of the ionization constant, K a, for this acid? a b c d e ph = [H ] = 10 ph = Or (shift log 1.301) = 0.05 [H ] = (Ka x C o ) = (Ka x C o ) 1/2 = (K a x 0.1) [H ] 2 = (Ka x C o ) = (K a x 0.4) (0.05) 2 = K a x 0.4 K a = 2.5 x10 3 / 0.4= A M solution of a weak base in water has a ph = at 25 C. Calculate the value of K b for this base. a * b c d e

6 ph = [H ] = 10 ph = Or (shift log 10.40) = 3.98 x [OH ]= 1 x / [H ] = 1 x / 3.98 x = 2.52 x 10 4 [OH ] 2 = (K b x C o ) = (K b x 0.2) (2.52 x 10 4 ) 2 = K b x 0.2 K b = 6.3 x10 8 / 0.2= The ionization constant, K a, for benzoic acid, HC 7 H 5 O 2, is What is the ph of a 0.15 molar solution of this acid? a * b c d e ph = log [H ] = log K a x C o = log (K a x C o ) 1/2 = log ( x 0.15) 1/2 = log 3.07 x 10 3 = 2.52 Extra Exercise 22. What is the conjugate acid of NH 3? A) NH 3 B) NH 4 OH C) NH 2 D) NH 3 E) NH The conjugate base of HSO 4 is A) HSO 4 B) H 3 SO 4 C) OH D) H 2 SO 4 E) SO The conjugate acid of HSO 4 is A) SO 4 2 B) H C) HSO 4 D) HSO 3 E) H 2 SO What is the conjugate base of OH? A) O B) H 2 O C) H 3 O D) O 2 E) O What is the ph of an aqueous solution at 25.0 C in which [H ] is M? A) 2.60 B) 3.40 C) 2.60 D) 3.40 E) What is the ph of an aqueous solution at 25.0 C in which [OH ] is M? A) 2.60 B) 2.60 C) 11.4 D) 11.4 E)

7 28. What is the ph of an aqueous solution at 25.0 C that contains M hydronium ion [H 3 O ]? A) 5.60 B) 7.00 C) 8.40 D) 9.00 E) What is the ph of an aqueous solution at 25.0 C that contains M hydroxide ion [OH ]? A) 5.60 B) 9.00 C) 7.00 D) 3.98 E) What is the concentration (in M) of hydronium ions in a solution at 25.0 C with ph = 4.282? A) 4.28 B) C) D) 9.71 E) What is the concentration (in M) of hydroxide ions [OH ] in a solution at 25.0 C with ph = 4.282? A) 9.72 B) C) D) E) Calculate the poh of a solution at 25.0 C that contains M hydronium ions [H 3 O ]?. A) 1.94 B) 7.00 C) 9.71 D) 4.29 E) Calculate the concentration (in M) of hydronium ions [H 3 O ] in a solution at 25.0 C with a poh of A) B) C) D) E) What is the ph of a M aqueous solution of barium hydroxide Ba(OH) 2? A) 10.4 B) 1.52 C) 12.2 D) 12.5 E) What is the poh of a M solution of barium hydroxide Ba(OH) 2? A) 12.2 B) 10.4 C) 1.82 D) 12.5 E)

8 36. An aqueous solution contains M NaOH at 25.0 C. The ph of the solution is. A) 1.00 B) 1.00 C) 7.00 D) 13.0 E)