C) SO 4 H H. C) The N-atom is the Lewis base because it accepted a pair of electrons to form the

Transcription

1 AP Chemistry Test (Chapters 14 and 15) 1) Which one would hydrolyze water the most? A) Ca 2+ B) NO 3 - C) SO 4 2- H H D) CN - 2) Which one is true about the compound? H B-N H A) The N-atom is the Lewis acid because it accepted a pair of electrons to form the B-N bond. B) The N-atom is the Lewis base because it donated a pair of electrons to form the B-N bond. C) The N-atom is the Lewis base because it accepted a pair of electrons to form the B-N bond. D) The B-atom is the Lewis acid because it donated a pair of electrons to form the B-N bond. E) The B-atom is the Lewis base because it accepted a pair of electrons to form the B-N bond. 3) What is the conjugate base of H 5 X 2 Z +6? 4) Which aqueous solution would have a > 7? H H A) HCl B) H 2 C 2 O 4 C) NH 4 Cl D) K 2 SO 4 E) Li 2 C 2 O 4 5) Which aqueous solution would have a < 7? A) NH 4 ClO 3 B) CaI 2 C) CH 3 NH 2 D) Ba(OH) 2 E) KC 2 H 3 O 2 6) Which one could be neutralized by a weak acid? A) HCl B) H 3 PO 4 C) K 2 O (s) in H 2 O D) Cl 2 O 7 (g) in H 2 O 7) Please choose all answers that rank the acids in order of increasing bond strength. i) HBr, HCl ii) HCl, HF iii) H 2 Se, H 2 Te iv) H 3 As, H 3 P A) i B) i, ii, iv C) i, ii D) i, ii, iii E) iii

2 8) In a sample of pure water, which statement is always true at all conditions of temperature and pressure? A) [H 3 O + ] = 1.0 X 10 7 M B) [OH ] = 1.0 X 10 7 M C) = 7.0 D) poh = 7.0 E) [H 3 O + ] = [OH ] 9) What is the of a solution that is 1 X M HCl at 25 o C? A) 12 B) 2 C) 7 D) 0.2 E) ) Which of these acids is the strongest? A) K a = 4.25 X 10 2 B) K a = 6.25 X 10 5 C) K a = 2.15 X 10 8 D) K a = 3.00 X ) When solid NH 4 Cl is added to water, the?. A) remains at 7. B) becomes greater than 7 because the Cl - hydrolyzes water. C) becomes less than 7 because the Cl - hydrolyzes water. D) becomes less than 7 because the NH + 4 hydrolyzes water. E) becomes greater than 7 because the NH + 4 hydrolyzes water. 12) At the equivalence point of a titration, which one is always true? A) The species are water and conjugate acid or base. B) There species are water, conjugate acid or base and excess acid. C) The species are water, conjugate acid or base and excess base. D) The is 7. 13) When a weak acid of known concentration is titrated with a strong base of unknown concentration, which one is always true at the half-equivalence point? A) The molarity of the base can be determined. B) The Ka of the acid can be determined. C) The species are water and conjugate base. D) The base is the excess reagent. E) The conjugate base is the excess reagent. 14) Which one best predicts the at the equivalence point when a weak acid is titrated with a strong base? A) Greater than 7 because the cation of the weak acid hydrolyzes the water. B) Greater than 7 because the anion of the weak acid hydrolyzes the water. C) Greater than 7 because the anion of the strong base hydrolyzes the water. D) Less than 7 because the anion of the weak acid hydrolyzes the water. E) Less than 7 because the cation of the strong base hydrolyzes the water.

3 15) Which graph illustrates a weak base titrated with a strong acid? A) B) C) D) 16) Please arrange these bases in order of increasing basicity (weak base to strong base). NH 3 Kb = 1.8 X 20-5 BrO - Ka = 2.0 X 10-9 for HBrO CN - Ka = 6.2 X for HCN H 2 O Kw = 1.00 X A) NH 3 > CN - > BrO - > H 2 O B) H 2 O > BrO - > NH 3 > CN - C) BrO - > CN - > H 2 O > NH 3 D) H 2 O > CN - > BrO - > NH 3 E) H 2 O > BrO - > CN - > NH 3 17) Water has Kw = X at 60 o C. What is the of water at 50 o C? A) 7.00 B) 6.78 C) 6.92 D) ) Which indicator would be most useful in a titration where the equivalence point was approximately 3.8? A) Bromophenol blue yellow 4 blue B) Bromcresol purpler yellow 6 purple C) Phenolphthalein clear 9 fuschia D) Bromothymol blue yellow 7 blue 19) Which one is true about an acid solution? A) The larger the Ka, the lesser the dissociation and the lower the. B) The larger the Ka, the higher the dissociation and the lower the. C) The larger the Ka, the lesser the dissociation and the higher the. D) The larger the Ka, the higher the dissociation and the higher the.

4 20) Which species is the conjugate acid? H 2 NNH 2 + H 2 O H 2 NNH OH - A) H 2 NNH 2 B) H 2 O C) + H 2 NNH 3 D) OH - 21) Please consider the conjugal pair HC 2 O 4 - /C 2 O 4-2 in water. Which statement is true? A) The C 2 O -2 4 is the base that accepted an H + from the water. B) The HC 2 O - 4 is the acid that donated an H + to the water. C) The HC 2 O - 4 is the acid that accepted an H + from the water. D) The C 2 O -2 4 is the conjugate acid. 22) Which one is a polyprotic acid? A) HBr B) HSO 3 - C) H 2 CrO 4 D) (NH 4 ) 3 PO 4 23) Which pair could be a buffer? A) HC 2 H 3 O 2 /H + B) NH 3 /Cl - C) + NH 3 /NH 4 D) NaOH/Na + E) HNO 3 /NO - Please write a net ionic reaction for each of the following. 24) Tetraphosphorous decoxide is dropped into water. 25) Dinitrogen pentoxide gas is bubbled through water. Please consider this buffer: C 5 H 5 N + HOH C 5 H 5 NH + + OH - 26) Please write the net ionic reaction that occurs when an acid H + is added to this buffer. Please consider this buffer: H 2 P 4 O H 2 O HP 4 O H 3 O + 27) Please write the net ionic reaction that occurs when an acid H + is added to this buffer.

5 AP Chemistry Test #2 (Chapters 14 and 15) 1) Which one would hydrolyze water the most? A) SO 4 2- B) NO 3 - C) Ba 2+ D) S 2-2) Which one is most likely to be a Lewis base? A) H 3 O + B) Al C) Br D) + NH 4 3) What base formed this conjugate acid, H 5 X 3 Z 2+? 4) What acid formed this conjugate base, H 2 X 3 Z -2? 5) Which salt would form an acidic solution when it dissolves in water? A) Al(CN) 3 B) Ba(NO 3 ) 2 C) Na 3 PO 4 D) CH 3 NH 2 I 6) Which salt would form a basic solution when it dissolves in water? A) (NH 4 ) 2 SO 4 B) Mg(CN) 2 C) K 2 CO 3 D) K 2 SO 4 7) Four of the following pairs of acids list the weaker acid on the left and the stronger acid on the right. Which pair is reversed? Weaker Acid Stronger Acid A) HIO 3 HBrO 3 B) HClO 4 HClO 3 C) H 3 PO 4 HNO 3 D) H 3 As H 3 P E) H 3 AsO 4 H 3 PO 4 8) Please choose all false statements for water at all conditions of temperature and pressure? A) [H 3 O + ] = 1.0 X 10 7 M B) [OH ] = 1.0 X 10 7 M C) [H 3 O + ] = [OH ] D) = poh E) Kw = 1 X Please use the following choices to answer questions 9-11.

6 A) 50 of 1 M H 2 C 2 O 4 mixed with 50 of 1 M KHC 2 O 4 B) 50 of 1 M KNO 3 mixed with 50 of 1 M HNO 3 C) 50 of 1 M NH 3 mixed with 50 of 1 M NH 4 NO 3 D) 50 of 1 M C 2 H 5 NH 2 mixed with 50 of 1 M KOH E) 50 of 1 M CH 3 NH 2 mixed with 50 of 1 M HC 2 H 3 O 2 9) Which solution is the most acidic (lowest )? 10) Which solution is a buffer with > 7? 11) Which solution is a buffer with < 7? 12) Which of these acids has the strongest conjugate base? A) K a = 4.25 X 10 9 B) K a = 6.25 X 10 3 C) K a = 2.15 X 10 5 D) K a = 3.00 X ) When Fe(NO 3 ) 2 is dissolved in water, A) the solution is acidic because the iron ion hydrolyzes water. B) the solution is neutral. C) the solution is basic because the iron ion hydrolyzes water. D) the solution is acidic because the nitrate ion hydrolyzes water. E) the solution is basic because the nitrate ion hydrolyzes water. Please consider the following graph to answer questions ) Which one best describes the experimental procedure used to obtain these lab results? A) A strong base was titrated with a weak acid. B) A weak acid was titrated with a strong base. C) A weak base was titrated with a strong acid. D) A strong acid was titrated with a strong base. E) A strong acid was titrated with a weak base. 15) Which one best describes the contents of the beaker at the equivalence point? A) Excess acid, salt & water B) Excess base, salt & water C) Salt & water

7 D) Water E) Excess acid & base 16) In addition to water, what are the contents of the beaker at point B? A) Acid only B) Base only C) Acid and base D) Acid and salt E) Base and salt

8 17) Which graph illustrates a strong acid titrated with a strong base? A) B) C) D) 18) Which one does not apply to the titration curve when a weak acid is titrated with a strong base? A) The equivalence point occurs at 7. B) At the equivalence point, the salt solution has a maximum molarity. C) Salt hydrolysis occurs at the equivalence point. D) A buffer exists during the titration up to the equivalence point. E) The jump at the equivalence point is smaller than if a strong acid was used. 19) Which one is arranged from the weakest to the strongest base at 25 o C? HCN Ka = 2.5 X NH 3 Kb = 1.8 X 10-5 A) H 2 O, ClO - 4, CN -, NH 3 B) CN - -, NH 3, H 2 O, ClO 4 C) ClO - 4, H 2 O, NH 3, CN - D) NH 3, CN - -, H 2 O, ClO 4 E) ClO - 4, H 2 O, CN -, NH 3, 20) Water has Kw = X at 5 o C. What is the of water at 5 o C? 21) Which one would hydrolyze water the most? A) NaC 2 H 3 O 2 HC 2 H 3 O 2 Ka = 1.8 X 10-5 B) NaC 3 H 5 O 3 HC 3 H 5 O 3 Ka = 1.4 X 10-4 C) NaClO 2 HClO 2 Ka = 1.2 X 10-2 D) NaOC 6 H 5 HOC 6 H 5 Ka = 1.6 X 10-10

9 Please use the following reaction to answer questions H 3 J 2 L -4 + H 2 GT 7 2+ H 4 J 2 L -3 + HGT ) Which species is the conjugate acid? 23) Which species is the base? 24) Please consider the conjugal pair H 2 PO 4 - /HPO 4 2- in water. Which statement is true? A) The HPO 2-4 is an acid that donated an H + to the water. B) The H 2 PO - 4 is the conjugate base. C) The H 2 PO - 4 is an acid that donated an H + to the water. D) The HPO 2-4 is a base that donated an H + to the water. 25) Which one is a diprotic acid? A) H 2 C 2 O 4 B) HNO 3 C) HClO D) H 3 PO 4 26) What is the purpose of a buffer? A) To absorb the conjugate base of an acid B) To absorb H + and OH - C) To absorb the conjugate acid of a base D) To absorb salts 27) Please consider the combination of NaOH and NaClO 4 in water. Which one is true? A) It is not a buffer because it cannot absorb H +. ` B) It is not a buffer because it cannot absorb OH -. C) It is a buffer because it absorbs H +. D) It is a buffer because it absorbs OH -. 28) Which one is false about indicators? A) They are weak organic acids. B) The acid and conjugate base exist as different colors. C) They utilize LeChatelier s principle to shift from one color to another. D) They change when pka of the indicator = of the acid or base used in the titration. 29) Which indicator would be most useful in a titration where the equivalence point was approximately 3? A) Bromophenol blue yellow 4 blue B) Bromcresol purple yellow 6 purple C) Phenolphthalein clear 9 fuschia D) Bromothymol blue yellow 7 blue Please write a net ionic reaction for each of the following. 30) Ammonium nitrate is added to water.

10 31) Dinitrogen pentoxide gas is bubbled through water. 32) Solid vanadium (V) oxide is added to water. For 35-36, please consider this buffer: HPO HOH H 3 O + + PO ) Please write the reaction that occurs when an acid H + is added to this buffer. 34) Please write the reaction that occurs when a base OH - is added to this buffer. For 37-38, please consider this buffer: C 5 H 5 N + HOH C 5 H 5 NH + + OH - 35) Please write the reaction that occurs when an acid H + is added to this buffer. 36) Please write the reaction that occurs when a base OH - is added to this buffer.

11 AP Chemistry Test (Chapters 14 and 15) Name 1) 16) 2) 17) 3) 18) 4) 19) 5) 20) 6) 21) 7) 22) 8) 23) 9) 10) 11) 12) 13) 14) 15) 24) 25) 26) 27)