Question 1

When the pH of a solution is 1, the concentration of hydronium ions is  M, which is the same as 0.1 M. Assume that the volume of this solution is 500 mL and that the solution is not buffered. What would be the new pH of this solution after 500 mL of pure water is added? You will need a calculator with a log function to answer this question.

Accepted Answer

A)  13 
B)  1.3 
C)  0.13 
D)  1.03

Question 2

How might warmer oceans accelerate global warming?

Accepted Answer

A)  The evaporation of water from the ocean would increase significantly. 
B)  The solubility of C  in water decreases as temperatures rise. 
C)  The heat collected by the ocean water would be radiated back into the atmosphere. 
D)  There would be less snow in the winter.

Question 3

At what point will a buffer solution cease to moderate changes in pH?

Accepted Answer

A)  when waters equilibrium constant  has been reached 
B)  when the weak acid and the weak base salt concentration are equal 
C)  when the acting buffering component is all neutralized 
D)  only after all the acid or the base that needs to be buffered has been added

Question 4

Which of the following statements describes an acidic solution?

Accepted Answer

A)  [H3O+] > [OH-] 
B)  [H3O+] -] 
C)  [H3O+] × [OH-] ≠ 1 × 10-14 
D)  [H3O+]/[OH-] = 1 × 10-14 
E)  [H3O+]/[OH-] = 1

Question 5

Some molecules are able to stabilize a negative charge by passing it from one atom to the next by a flip-flopping of double bonds. This occurs when the negative charge is one atom away from an oxygen double bond as follows. Note that the curved arrows indicate the movement of electrons:  Why then is sulfuric acid so much stronger an acid than carbonic acid?

Accepted Answer

A)  In sulfuric acid, the negative charge is able to flip-flop to two additional oxygens rather than only one as is the case for carbonic acid. 
B)  The two double bonded oxygens in   tend to destabilize the single bonded oxygens once the hydrogen ions form, thus making sulfuric acid more acidic. 
C)  Since carbonic acid has resonance stabilization and sulfuric acid does not, sulfuric acid is less stable and more acidic. 
D)  The acid strength of two comparative molecules is directly proportional to the number of number of oxygens directly bonded to the central atom. Sulfuric acid, having four such oxygens, is more acidic.

Question 6

What results when water,  O, reacts with sulfur dioxide, S  ?

Accepted Answer

A)   O + S  →   (aq) 
B)  2  O + 2 S  → 2    (aq) +  (g) 
C)   O + S  → S  (g) +  (g) 
D)   O + S  → No Reaction

Question 7

According to the following reaction, which molecule is acting as an acid? H3O+ + HSO4- → H2O + H2SO4

Accepted Answer

A)  H2SO4 
B)  H2O 
C)  H3O+ 
D)  HSO4- 
E)  none of the above

Question 8

Which of the following solutions is the most acidic?

Accepted Answer

A)  a solution with a pH = 14 
B)  a solution with a pH = 10 
C)  a solution with a pH = 7 
D)  a solution with a pH = 4 
E)  All of the solutions are basic.

Question 9

When the hydronium ion concentration equals 1 mole per liter, what is the pH of the solution? Is the solution acidic or basic?

Accepted Answer

A)  pH = 0, this is an acidic solution. 
B)  pH = 1, this is an acidic solution. 
C)  pH = 10, this is a basic solution. 
D)  pH = 7, this is a neutral solution.

Question 10

Suggest why people once washed their hands with ashes.

Accepted Answer

A)  The ashes act as a base and reacts with skin oils to produce solutions of soap. 
B)  The ashes act as an acid and reacts with the skin oils to produce soap. 
C)  The oils on the skin act as a base and reacts with the ashes to produce soap. 
D)  After being burnt in the fire, the acids and bases of the log are neutralized, making it a gentle material to use on the hands.

Question 11

Cutting back on the pollutants that cause acid rain is one solution to the problem of acidified lakes. Suggest another.

Accepted Answer

A)  stop using NaCl to salt the roads in the winter 
B)  add a neutralizing substance such as limestone 
C)  add ammonium ions to the lakes 
D)  add chlorine and filter the water to remove any acidity in the lake

Question 12

Sometimes an individual going through a traumatic experience cannot stop hyperventilating. In such a circumstance, it is recommended that the individual breath into a paper bag or cupped hands as a useful way to avoid an increase in blood pH, which can cause the person to pass out. Explain how this works.

Accepted Answer

A)  Carbon dioxide initially exhaled is reinhaled to help maintain adequate levels of carbonic acid in the blood. 
B)  It helps to slow their breathing down to prevent excess oxygen from entering the blood. 
C)  The paper absorbs C  to prevent the accumulation of excess C  in the blood. 
D)  The paper bag helps to retain the water vapor leaving the mouth to prevent an increase in the concentration of lactic acid in the body.

Question 13

Which of the following statements is not true about a neutralization reaction?

Accepted Answer

A)  Water is always formed in a neutralization reaction. 
B)  One molecule of acid neutralizes one molecule of base. 
C)  A neutralization is the reaction of a hydroxide ion with a proton. 
D)  All of the above are true. 
E)  None of the above are true.

Question 14

What is the hydroxide ion concentration in an aqueous solution where the pH = 5?

Accepted Answer

A)  The hydronium ion concentration equals 1 ×  . 
B)  The hydronium ion concentration equals 1 ×  . 
C)  The hydronium ion concentration equals 1 ×  . 
D)  The hydronium ion concentration equals 1 ×  .

Question 15

For the following reaction, identify whether the compound in bold is behaving as an acid or a base. H3PO4 + H2O ⇌ H2PO4- + H3O+

Accepted Answer

A)  acid 
B)  base 
C)  neither 
D)  both 
E)  none of the above

Question 16

What would the concentration of H3O+ be if the concentration of OH- was 1 × 10-11M? [H3O+] × [OH-] = Kw = 1 × 10-14

Accepted Answer

A)  1 × 10-3 
B)  1 × 103 
C)  1 × 1014 
D)  1 × 1012 
E)  1 × 10-6

Question 17

As the hydronium ion concentration increases, the pH ________.

Accepted Answer

A)  goes down 
B)  gets larger 
C)  starts to affect the OH- concentration 
D)  starts to alter the chemical properties of the water molecules 
E)  stays constant

Question 18

What is the main characteristic of a strong acid?

Accepted Answer

A)  It is completely dissociated in water. 
B)  It readily gives up its proton to a base. 
C)  It is corrosive. 
D)  It will damage your skin. 
E)  all of the above

Question 19

Why do we use the pH scale to indicate the acidity of a solution rather than simply stating the concentration of hydronium ions?

Accepted Answer

A)  It includes the concentration of hydronium and hydroxide ions. 
B)  It is used because the general public understands it. 
C)  It is more accurate to use the pH scale. 
D)  It is more convenient, since the concentration of hydronium ions is so small.

Question 20

For the following acid-base reaction, identify what is formed in the space marked. HF + KOH ⇌ ???? + H2O

Accepted Answer

A)  KF 
B)  H3OF 
C)  KOH2 
D)  KOH2F 
E)  none of the above

Exam 10: Acids and Bases in Our Environment