Quiz 14

 

Quiz 14  



Question 1

The pH of a cup of coffee (at 25°C) was found to be 5.12. What is the hydronium-ion (H3O+) concentration? Answers: A. 5.12 x102  -6

B. 7.59 x10   C. 5.12 D. 7.59 x102   



Question 2

Fill-in the blank: Theory

Acids H+ donor in aqueous solution Proton (H+) donor in aqueous solution

Bases OH- donor in aqueous solution Proton (H+) acceptor in aqueous solution

e- pair acceptor

e- pair donor

Answers: A. Arrhenius/Lewis/ Bronsted-Lowry B. Arrhenius/Bronsted-Lowry/Lewis C. Lewis/Arrhenius/Bronsted-Lowry D. None of the above  



Question 3

The addition of hydrofluoric acid and __________ to water produces a buffer solution. Answers: A. NaBr B. HCl C. NaF D. NaCl  



Question 4

What is the pH of an aqueous solution at 25.0 °C in which is 0.0025 M? Answers:

A. 11.4 B. 10.4 C. 9.60 D. 2.60

 

   



Question 5

Of the species below, only __________ is not an electrolyte.

Answers: A. Rb2SO4 B. Ar C. KOH D. HCl  



Question 6

What is the pH of a solution in which 150 mL of 0.10 M NaOH is added to 25 250 0 mL of 0.10 M HCl? Answers: A. 1.0 B. 13 C. 1.6 D. 2.0  



Question 7

How many moles of sodium acetate must be added to 2.0 L of 0.25 M acetic acid to give a solution that has a pH equal to 5.00? Ignore the volume change due to the addition of sodium acetate. The value of Ka of acetic acid is 1.76 x10 -5  Answers: A. 0.44 B. 1.10 C. 0.88 D. 0.22  



Question 8

Given three compounds in water as below, b elow, which compound is strongest electrolyte? (For simplicity water molecules are not shown)?

 

 

Answers: A. A B. Inadequate information to conclude C. C D. B  



Question 9

Which salt will produce an acidic solution upon upo n dissolving? Answers: A. Ba(CH3COO)2  B. NH4Cl C. NaCl D. KNO3   



Question 10

Acrylic acid, whose formula is HC 3H3O2 or HO2CCH=CH2, is used in the manufacture of  plastics. A 0.15M aqueous solution of acrylic acid has a pH of 2.6. What is Ka for acrylic acid? Answers: A. 2.5x10-3  B. 5.6 x10-5  C. 0.71 D. 4.3 x10-5   



Question 11

Identify electrolyte(s) among AgCl, BaSO4, NaCl (table salt), Mg(NO3)2, C12H22O11 (sugar), C6H6  Answers:

A. NaCl, Mg(NO3)2  B. BaSO4, C12H22O11, NaCl C. Mg(NO3)2, C12H22O11, AgCl

 

   



D. NaCl, Mg(NO3)2, C6H6 

Question 12

Which one of the following is the weakest acid Answers: A. HNO2 (K a = 4.5 x 10 -4) B. HClO (K a = 3.0 x 10 -8) C. HF (K a = 6.8 x 10-4) D. HCN (K a = 4.9 x 10-10)

 



Question 13

A detergent solution has a pH of 10.93 at 25°C. What is the hydroxide-ion concentration (OH-)? Answers: A. 1.175 x10-11  -4

B. 1.276 x10   C. 8.511 x10-4  D. 2.375 x10-4   



Question 14

Give the conjugate base to HPO42- regarded as acid. Answers: A. H2PO4-  B. HPO4-  C. PO43-  D. H3PO4   



Question 15

In a solution, when the concentrations of a weak acid and its conjugate base are equal A.the -log of the [H+] and the -log of the K a are equal.

Answers:

B. the buffering capacity is significantly decreased. C. the system is not at equilibrium D. all of the above are true.  



Question 16

What is the base-dissociation constant, K  b, for quinoline? Quinoline has a K a = 1.2 x 10-5. Answers: A. 1.0 x 10-14 

 

 

B. 1.2 x 10-5  C. 4.92 D. 8.3 x 10-10 

 



Question 17

An artificial fruit beverage contains 30.0 g of tartaric acid, H2C4H4O6, and 18.8 g of its salt,  potassium hydrogen tartrate, per liter. What is the pH of the beverage? K aa11 = 1.0 x10-3  Answers: A. 3.57 B. 2.02 x10-3 C. 2.69 D. 11.31  



Question 18

What is the pK a for aniline if the K  b is 4.3 x 10-10? Answers: A. 9.36 B. 4.63 C. 1.8 x 10 -5  D. 2.3 x 10-5   



Question 19

Given lemon juice (pH 2.2-2.4), beer (pH 4.0-4.5), milk (pH 6.4), baking soda (pH 8.4), identify acidic solution. Answers: A. Beer, milk, banking soda B. All C. Lemon juice, beer, baking soda D. Lemon juice, beer, milk  



Question 20

A buffer is prepared by adding 115 mL of 0.37 M NH3 to 145 mL of 0.25 M NH4 NO3. What is the pH of the final solution? The value of Kb is 1.8 x10-5  Answers: A. 4.7 B. 5.3 C. 9.3 D. 8.7