Chemisty Exam 3

How many of the following is a weak acid? HClO4 H2SO4 HCl CH3COOH NaOH

1

How many of these are amphoteric? H2O HF H2PO4- NaOH

2

Which of the following is TRUE? A) The equivalence point is where the amount of acid equals the amount of base during any acid-base titration. B) At the equivalence point, the pH is always 7. C) An indicator is not pH sensitive. D) A titration curve is a plot of pH vs. the [base]/[acid] ratio. E) None of the above are true.

A) The equivalence point is where the amount of acid equals the amount of base during any acid-base titration.

Which statement about HF and/or HClO is correct? A) They are both weak acids. B) They are both strong acids. C) They both weak bases D) HF is the only strong acid of the two. E) HClO is the only strong acid of the two.

A) They are both weak acids.

Identify the most common indicator. A) phenolphthalein B) thymol blue C) crystal violet D) alizarin E) alizarin yellow R

A) phenolphthalein

Which of the following is TRUE? A) The equivalence point is where an acid changes into a base. B) The point where the indicator changes color is called the endpoint. C) An indicator is a combination of an acid and base that can resist's changes in pH. D) At the equivalence point, the pH is always 7. E) None of the above are true.

B) The point where the indicator changes color is called the endpoint.

If the pKa of HCHO2 is 3.74 and the pH of an HCHO2/NaCHO2 solution is 3.74, which of the following is TRUE? A) [HCHO2] > [NaCHO2] B) [HCHO2] = [NaCHO2] C) [HCHO2] < [NaCHO2] D) [HCHO2] < <[NaCHO2] E) It is not possible to make a buffer of this pH from HCHO2 and NaCHO2.

B) [HCHO2] = [NaCHO2]

Which of the following would MOST LIKELY have the highest pH? A) lemons B) apples C) Drano D) Tums (antacid)

C) Drano

Given the following reaction, which statement is true in the forward direction? HPO42-(aq) + HF (aq) H2PO4-(aq)+ F- (aq) A) HPO42-is the base and F- is its conjugate acid. B) HPO42-is the acid and H2PO4-is its conjugate acid. C) HF is the acid and F- is its conjugatebase. D) HFis the base and F- is its conjugate acid. E) HPO42-is the acid and F- is its conjugate base.

C) HF is the acid and F- is its conjugatebase.

Which one of the following statements is the correct definition of a Lewis Base? A) an electron acceptor B) combines with or accepts H+ C) an electron donor D) donates a H+ E) increases OH- concentration

C) an electron donor

Which one of the following statements is TRUE? A) A buffer is an aqueous solution composed of any kind salt and acid. B) A buffer changes color at the endpoint of a titration. C) A buffer does not change pH when strong acid or base is added. D) A buffer resists pH change by neutralizing added acids and bases. E) None of the above are true.

D) A buffer resists pH change by neutralizing added acids and bases.

Identify the acid that is in car batteries. A)CH3COOH, acetic acid B)HNO3 C)H2CO3 D) H2SO4

D) H2SO4

Given the following acids and their associated pKa's, which is the weakest acid? A) HOOCCl3 (pKa = 0.7) B) HCOOH (pKa = 4.7) C) H3PO4(pKa = 2.1) D) HCN(pKa = 9.3) E) H2CO3(pKa = 6.4)

D) HCN(pKa = 9.3)

Given the following acids and their associated pKa's, which is the weakest conjugate base? A) NH4+ (pKa = 9.2) B) H2SO3 (pKa = 1.8) C) CH3COOH (pKa = 4.7) D) HOOCCOOH (pKa = 1.2) E) H3PO4 (pKa = 2.1)

D) HOOCCOOH (pKa = 1.2)

Which of the following is FALSE? A)An Arrhenius acid and Arrhenius base react together to form an ionic salt and water. B)HCl is an Arrhenius acid because it produces H+ ions in aqueous solution. C)HCl is a Bronsted-Lowry acid because it donates a proton to water. D) Lewis Bases are electron pair acceptors.

D) Lewis Bases are electron pair acceptors.

The stronger the base, then which of the following is true? A) The stronger the conjugate acid. B) The stronger the conjugate base. C) The weaker the conjugate base. D) The weaker the conjugate acid. E) None of the above.

D) The weaker the conjugate acid.

Identify a good buffer. A) small amounts of both a weak acid and its conjugate base B) significant amounts of both a strong acid and a strong base C) significant amounts of both a weak acid and a strong acid D) significant amounts of both a weak acid and its conjugate base

D) significant amounts of both a weak acid and its conjugate base

10. Which of the following bases is the strongest? The base is followed by its Kb value. A)HOCH2CH2NH2, 3.2 × 10-5 B)NH3, 1.76 × 10-5 C)C5H5N, 1.7 × 10-9 D)(CH3CH2)3N, 5.2 × 10-4 E) Since these are all weak bases, they have the same strength.

D)(CH3CH2)3N, 5.2 × 10-4

Consider the following acids: HClO3 HClO4 HClO HClO2. Identify the weakest and the strongest. A)HClO2<HClO3 B)HClO3<HClO4 C)HClO<HClO3 D)HClO<HClO4 E)HClO4<HClO

D)HClO<HClO4

Which of these is a Neutralization reaction? A) NH4+ (aq) + H2O (l) NH3 (aq) + H3O+ (aq) B) Na2CO3(aq) + Fe(NO3)2 (aq) FeCO3 (s) + 2 NaNO3 (aq) C) Mg(s) + Fe(NO3)2 (aq) Fe (s) + Mg(NO3)2 (aq) D) (NH4)2CO3 2 NH3 (g) + H2O (g) + CO2 (g) E) Ba(OH)2 (aq) + 2 HNO3 (aq) Ba(NO3)2 (aq) + 2 H2O (aq)

E) Ba(OH)2 (aq) + 2 HNO3 (aq) Ba(NO3)2 (aq) + 2 H2O (aq)

When titrating a weak base with a strong acid at 25°C, the A) pH will be 7 at the equivalence point. B) pH will be greater than 7 at the equivalence point. C) titration will require more moles of the base than acid to reach the equivalence point. D) titration will require more moles of acid than base to reach the equivalence point. E) pH will be less than 7 at the equivalence point.

E) pH will be less than 7 at the equivalence point.

Which of the following is an example of a Lewis Acid? I. Cr+3 (aq) II. NH4+ (aq) III. Ba+2 (aq) IV. C5H5N

I & III only

Which of the following salts results in an Basic solution when dissolved in water? I. NaCN II. KCl III. KClO2 IV. CH5NHBr

I & III only

Which of the following has the correct conjugate acid of what is to its left? left CA I. H2O OH- II. O-2 OH- III. HS- H2S IV. NH3 NH2-

II & III only