Question 1

Pour vinegar onto beach sand from the Caribbean and the result is a lot of froth and bubbles. Pour vinegar onto beach sand from California, however, and nothing happens. Why?

Accepted Answer

A) Beaches in tropical climates generally have remnants of volcanic deposit not present in California sand. These deposits contain soil with organic residue. Vinegar's acetic acid reacts with organic matter. 
B) The pH of the warm sands of tropical waters is well into the basic range, unlike the beach sand in California. Therefore, the acidic vinegar reacts with Caribbean beach sand but not with sand from California. 
C) Beach sand from the Caribbean and many other tropical climates is made primarily of the calcium carbonate remains of coral and shelled creatures. Vinegar is an acid and the calcium carbonate is a base. 
D) Caribbean beach sand contains deposits from the mouth of the Mississippi river which carries with it a great deal of contamination from urban waste. These warm water contaminates react with the acid in vinegar.

Question 2

Which should be a stronger base: ammonia,  , or trifluoronitrogen,  ? Why?

Accepted Answer

A)   ; The fluorine atoms, being already highly electronegative, repel and tend to release the lone electron pair more easily, making it the stronger base. 
B)   ; The fluorines have greater electronegativities and pull the lone pair electrons closer to nitrogen, thus making  less willing to release the electron pair and thus be a weaker base. 
C)   ; Ammonia tends to form a very pungent but weak base.   will definitely form a stronger base since the highly polar fluorines have replaced the weak hydrogens. 
D) Neither; The nitrogens are large enough to shield the effect of either the hydrogens or fluorines from exerting any appreciable influence over the electron pair. Both molecules will have nearly identical base strength.

Question 3

Which of the following statements describes a basic 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 4

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 5

Sodium hydroxide is added to a buffer solution of ammonia, N  , and ammonium chloride,  . What is the effect on the concentration of ammonia? What is the effect on the concentration of ammonium chloride?

Accepted Answer

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

Question 6

Why is the H-F bond so much stronger than the H-I bond?

Accepted Answer

A) H-F is a stronger bond because hydrogen and fluorine are more similar in nature than hydrogen and iodine. Both hydrogen and fluorine are diatomic and gases at room temperature. 
B) H-F is stronger bond because iodine forms a solid at room temperature and fluorine forms a gas. Also, iodine tends to sublime at room temperature. 
C) H-F is stronger because the fluorine atom is smaller and closer to the hydrogen atom causing greater attraction. 
D) Actually, H-I is stronger because the electronegativity of the iodine atom is smaller that that of the fluorine atom.

Question 7

What is an acid?

Accepted Answer

A) anything that donates hydrogen ions 
B) anything that accepts hydrogen atoms 
C) anything that donates hydrogen atoms 
D) anything that dissolves metal 
E) anything that donates hydronium ions

Question 8

What happens to the pH of soda water as it loses its carbonation?

Accepted Answer

A) It does not change since the carbonation has nothing to do with pH. 
B) It decreases as it loses the carbon dioxide molecules which form the carbonic acid in the soda. 
C) It increases as it loses the carbon dioxide molecules which form the carbonic acid in the soda. 
D) It decreases as the soda becomes more concentrated through the loss of the carbon dioxide gases.

Question 9

The overall rate at which humans are producing carbon dioxide is ________.

Accepted Answer

A) increasing 
B) decreasing 
C) some years increasing and other years decreasing 
D) remaining about the same

Question 10

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 11

Which of the above illustrations shows a neutral aqueous solution?

Accepted Answer

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

Question 12

Which of the following items would you use to make a basic buffer solution?

Accepted Answer

A) acetic acid (a weak acid)and hydrochloric acid (a strong acid) 
B) sodium hydroxide (a strong base)and sodium chloride 
C) acetic acid (a weak acid)and sodium acetate 
D) hydrochloric acid (a strong acid)and sodium hydroxide (a strong base) 
E) ammonium hydroxide (a weak base)and ammonium chloride

Question 13

If the pH of a solution is 10, what is the hydroxide ion concentration?

Accepted Answer

A) 1 × 10-4 M 
B) 4 M 
C) 14 M 
D) -14 M 
E) - 1 × 1014 M

Question 14

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

Accepted Answer

A) The pH of this solution is 4, which is acidic. 
B) The pH of this solution is 8, which is basic. 
C) The pH of this solution is 6, which is acidic. 
D) The pH of this solution is 10, which is basic.

Question 15

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

Accepted Answer

A) 1 × 10-3 
B) 1 × 10-2 
C) 1 × 10-4 
D) 1 × 1013 
E) none of the above

Question 16

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 17

In the reaction below, what does the symbol ⇌ mean? OH- + NH4+ ⇌ H2O + NH3

Accepted Answer

A) It means that the forward and backward reactions are happening at the same time. 
B) It means that the reaction cannot decide which way to go. 
C) It means that the forward reaction does not progress. 
D) It means that the backward reaction happens as fast as the forward reaction and so the proton is not transferred at all. 
E) none of the above

Question 18

Arrange the following images of an aqueous base solution in order of increasing base strength:

Accepted Answer

A) A, B, C 
B) B, C, A 
C) C, B, A 
D) A, C, B 
E) All are equally strong.

Question 19

How might you tell whether or not your toothpaste contained either calcium carbonate, CaC  , or baking soda, NaHC  , without looking at the ingredients label?

Accepted Answer

A) if the toothpaste bubbles when heated 
B) if the toothpaste bubbles when added to ammonia, such as window cleaner 
C) if the toothpaste produces a salt (NaCl)when added to HCl 
D) if the toothpaste bubbles when added to vinegar

Question 20

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

Exam 10: Acids and Bases in Our Environment

Pour vinegar onto beach sand from the Caribbean and the result is a lot of froth and bubbles. Pour vinegar onto beach sand from California, however, and nothing happens. Why?

Which should be a stronger base: ammonia, , or trifluoronitrogen, ? Why?

Which of the following statements describes a basic solution?

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

Sodium hydroxide is added to a buffer solution of ammonia, N , and ammonium chloride, . What is the effect on the concentration of ammonia? What is the effect on the concentration of ammonium chloride?

Why is the H-F bond so much stronger than the H-I bond?

What is an acid?

What happens to the pH of soda water as it loses its carbonation?

The overall rate at which humans are producing carbon dioxide is ________.

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 neutral aqueous solution?

Which of the following items would you use to make a basic buffer solution?

If the pH of a solution is 10, what is the hydroxide ion concentration?

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

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

How might warmer oceans accelerate global warming?

In the reaction below, what does the symbol ⇌ mean? OH^- + NH₄⁺ ⇌ H₂O + NH₃

Arrange the following images of an aqueous base solution in order of increasing base strength:

How might you tell whether or not your toothpaste contained either calcium carbonate, CaC , or baking soda, NaHC , without looking at the ingredients label?