Question 1

What happens to the pH of an acidic solution as water is added?

Accepted Answer

A)  The pH is not influenced by the addition of water. 
B)  The pH will decrease as the solution becomes more dilute. 
C)  The pH will increase as the solution becomes more dilute. 
D)  The pH will decrease since more hydronium ions are produced from the water.

Question 2

In the following buffer system, what happens to the concentration of the highlighted molecule if you add acid in the form of H3O+? HF + NaF + H2O ⇌ F- + H3O+ + Na+

Accepted Answer

A)  increases 
B)  decreases 
C)  stays about the same 
D)  Buffers do not change. 
E)  none of the above

Question 3

Which of the above illustrations shows a basic aqueous solution?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  All of the above are neutral solutions. 
E)  none of the above

Question 4

Would it be easier or harder for a water molecule to donate a hydrogen ion if its polar H-O bond were even more polar? Why?

Accepted Answer

A)  Easier. As polarity increases the bond classification tends towards ionic. An ionic bond would mean a greater separation of positive and negative charge making it easier for the water molecule to donate a hydrogen ion. 
B)  Harder. Increasing the polarity makes the bond stronger. The stronger the bond the more difficult it would be for the water molecule to donate a hydrogen ion. 
C)  Neither. Increasing the polarity of the O-H bond would not affect the hydrogen bonding between the water molecules and therefore have no effect on the water molecule's ability to donate a hydrogen ion. 
D)  Both. The ability of the water molecule to donate a hydrogen ion is dependent upon the environment you place it in. If the surrounding molecules are more covalent, donating the electron would be harder. However, if water found itself in a highly polar environment, increasing the O-H polarity would make it easier.

Question 5

What do the brackets in the following equation represent? [H3O+] × [OH-] = Kw

Accepted Answer

A)  The brackets mean the molarity of the compound inside them. 
B)  The molecule inside does not react with the other molecules in brackets. 
C)  The molecule in brackets is undergoing hydrogen bonding with the other molecule in brackets. 
D)  The first molecule in brackets is an acid and it reacts with the second molecule in brackets, which is a base. 
E)  none of the above

Question 6

According to the following reaction, which molecule is acting as an acid? H2O + NH3 → OH- + NH4+

Accepted Answer

A)  H2O 
B)  NH3 
C)  OH- 
D)  NH4+ 
E)  none of the above

Question 7

If the rate at which we produce CO2 were to stop rising, the levels of CO2 in the atmosphere would ________.

Accepted Answer

A)  eventually level off 
B)  continue to rise 
C)  decrease as CO2 is absorbed by plants, soils, and the oceans 
D)  This cannot be reasonably predicted

Question 8

According to the following reaction, which molecule is acting as an acid? OH- + NH4+ → H2O + NH3

Accepted Answer

A)  H2O 
B)  NH3 
C)  OH- 
D)  NH4+ 
E)  none of the above

Question 9

Hydrogen chloride is added to a buffer solution of ammonia, N  , and ammonium chloride, N  ⁺Cl⁻. What is the effect on the concentration of ammonia? What is the effect on the concentration of ammonium chloride?

Accepted Answer

A)  HCl reacts with both the ammonia and ammonium chloride, so the concentration of both decreases. 
B)  HCl reacts with only the ammonium chloride, so the concentration of the ammonium chloride decreases and the concentration of ammonia increases. 
C)  HCl reacts with both the ammonia and ammonium chloride, so the concentration of both increases. 
D)  HCl reacts with only the ammonia, so the concentration of the ammonium chloride increases and the concentration of ammonia decreases.

Question 10

What is the main characteristic of a strong base?

Accepted Answer

A)  It is completely dissociated in water. 
B)  It readily accepts an acidic proton. 
C)  It is corrosive. 
D)  It will damage your skin. 
E)  all of the above

Question 11

Sodium hydroxide, NaOH, is a strong base, which means that it readily accepts hydrogen ions. What products are formed when sodium hydroxide accepts a hydrogen ion from a water molecule?

Accepted Answer

A)  water and sodium hydroxide 
B)  sodium hydroxide and hydronium ions 
C)  sodium ions and hydronium ions 
D)  sodium ions and water

Question 12

What would the concentration of OH- be if the concentration of H3O+ was 1 × 10-5M? [H3O+] × [OH-] = Kw = 1 × 10-14

Accepted Answer

A)  1 × 10-14 
B)  1 × 10-5 
C)  1 × 109 
D)  1 × 105 
E)  1 × 10-9

Question 13

Which of the above illustrations shows an acidic aqueous solution?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  All of the above are neutral solutions. 
E)  none of the above

Question 14

Which of the following statements about strong and weak bases is not true?

Accepted Answer

A)  A weak base does not completely dissociate in water. 
B)  A weak base will not react with a strong acid. 
C)  A strong base can be extremely corrosive. 
D)  A strong base will readily accept protons from even weak acids. 
E)  All of the above are untrue.

Question 15

According to the following reaction, which molecule is acting as a base? OH- + NH4+ → H2O + NH3

Accepted Answer

A)  H2O 
B)  NH3 
C)  OH- 
D)  NH4+ 
E)  none of the above

Exam 10: Acids and Bases in Our Environment

What happens to the pH of an acidic solution as water is added?

In the following buffer system, what happens to the concentration of the highlighted molecule if you add acid in the form of H₃O⁺? HF + NaF + H₂O ⇌ F^- + H₃O⁺_{+ Na}+

Which of the above illustrations shows a basic aqueous solution?

Would it be easier or harder for a water molecule to donate a hydrogen ion if its polar H-O bond were even more polar? Why?

What do the brackets in the following equation represent? [H₃O⁺] × [OH^-] = K_w

According to the following reaction, which molecule is acting as an acid? H₂O + NH₃ → OH^- + NH₄⁺

If the rate at which we produce CO₂ were to stop rising, the levels of CO₂ in the atmosphere would ________.

According to the following reaction, which molecule is acting as an acid? OH^- + NH₄⁺ → H₂O + NH₃

Hydrogen chloride is added to a buffer solution of ammonia, N , and ammonium chloride, N ⁺Cl⁻. What is the effect on the concentration of ammonia? What is the effect on the concentration of ammonium chloride?

What is the main characteristic of a strong base?

Sodium hydroxide, NaOH, is a strong base, which means that it readily accepts hydrogen ions. What products are formed when sodium hydroxide accepts a hydrogen ion from a water molecule?

What would the concentration of OH^- be if the concentration of H₃O⁺ was 1 × 10^-5M? [H₃O⁺] × [OH^-] = K_w= 1 × 10^-14

Which of the above illustrations shows an acidic aqueous solution?

Which of the following statements about strong and weak bases is not true?

According to the following reaction, which molecule is acting as a base? OH^- + NH₄⁺ → H₂O + NH₃