HL Paper 1

According to the Brønsted-Lowry theory, how does each species act in the equilibrium below?

\[{\text{C}}{{\text{H}}_3}{\text{COOH}} + {{\text{H}}_2}{\text{S}}{{\text{O}}_4} \rightleftharpoons {\text{C}}{{\text{H}}_3}{\text{COOH}}_2^ +  + {\text{HSO}}_4^ - \]

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Aqueous solutions of a weak acid and a strong acid of equal concentration are compared. Which statements are correct?
 
I.    The weak acid is less dissociated than the strong acid.
II.   The strong acid reacts with a metal oxide but the weak acid does not.
III.  The strong acid has greater conductivity than the weak acid.
 
A.  I and II only
B.  I and III only
C.  II and III only
D.  I, II and III



What is the pH of 1.0 × 10−3 mol dm−3 sodium hydroxide, NaOH(aq)?

Kw = 1.0 × 10−14

A.     3

B.     4

C.     10

D.     11




Which solutions have a pH less than 7?

I.     \({\text{N}}{{\text{a}}_2}{\text{C}}{{\text{O}}_3}({\text{aq)}}\)

II.     \({\text{[Fe(}}{{\text{H}}_2}{\text{O}}{{\text{)}}_6}{\text{]C}}{{\text{l}}_3}{\text{(aq)}}\)

III.     \({{\text{(N}}{{\text{H}}_4}{\text{)}}_2}{\text{S}}{{\text{O}}_4}{\text{(aq)}}\)

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III




What is the correct expression for the ionic product constant of water, \({K_{\text{w}}}\)?

A.     \({K_{\text{W}}} = \frac{{{\text{[}}{{\text{H}}^ + }{\text{]}}}}{{{\text{[O}}{{\text{H}}^ - }{\text{]}}}}\)

B.     \({K_{\text{W}}}{\text{ = }}\frac{{{\text{[}}{{\text{H}}_2}{\text{O]}}}}{{{\text{[}}{{\text{H}}^ + }{\text{][O}}{{\text{H}}^ - }{\text{]}}}}\)

C.     \({K_{\text{W}}} = {\text{[}}{{\text{H}}^ + }{\text{]}} + {\text{[O}}{{\text{H}}^ - }{\text{]}}\)

D.     \({K_{\text{W}}} = {\text{[}}{{\text{H}}^ + }{\text{][O}}{{\text{H}}^ - }{\text{]}}\)




Which of the following is an example of a Lewis acid–base reaction, but not a Brønsted–Lowry acid–base reaction?

A.     \({\text{2CrO}}_4^{2 - }{\text{(aq)}} + {\text{2}}{{\text{H}}^ + }{\text{(aq)}} \to {\text{C}}{{\text{r}}_2}{\text{O}}_7^{2 - }{\text{(aq)}} + {{\text{H}}_2}{\text{O(l)}}\)

B.     \({\text{Co(}}{{\text{H}}_2}{\text{O)}}_6^{2 + }{\text{(aq)}} + {\text{4HCl(aq)}} \to {\text{CoCl}}_4^{2 - }{\text{(aq)}} + {\text{4}}{{\text{H}}^ + }{\text{(aq)}} + {\text{6}}{{\text{H}}_2}{\text{O(l)}}\)

C.     \({\text{N}}{{\text{H}}_3}{\text{(aq)}} + {{\text{H}}^ + }{\text{(aq)}} \to {\text{NH}}_4^ + {\text{(aq)}}\)

D.     \({\text{C}}{{\text{H}}_3}{\text{CO}}{{\text{O}}^ - }{\text{(aq)}} + {{\text{H}}_2}{\text{O(l)}} \to {\text{C}}{{\text{H}}_3}{\text{COOH(aq)}} + {\text{O}}{{\text{H}}^ - }{\text{(aq)}}\)




What is the pH of a solution in which the hydroxide ion concentration is 1 × 10−11 mol dm−3 at 298 K?

Kw = 1 × 10−14 at 298 K

A.     3

B.     7

C.     11

D.     14




Which species acts as a Lewis and Brønsted–Lowry base?

A.      [Al(H2O)6]3+

B.      BF3

C.      NH4+

D.      OH




The table below shows data for the \({{K_{\text{a}}}}\) and \({{\text{p}}{K_{\text{b}}}}\) values for some acids and bases at 298 K.

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Which two formulas represent the weakest acid and the weakest base in the table?

A.     HClO and \({{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{N}}{{\text{H}}_{\text{2}}}\)

B.     \({{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{COOH}}\) and \({\text{N}}{{\text{H}}_{\text{3}}}\)

C.     \({{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{C}}{{\text{H}}_{\text{2}}}{\text{COOH}}\) and \({{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{N}}{{\text{H}}_{\text{2}}}\)

D.     HClO and \({\text{N}}{{\text{H}}_{\text{3}}}\)




Which species produced by the successive dissociations of phosphoric acid, H3PO4, are amphiprotic?

A.     HPO42− and PO43−

B.     H2PO4 and HPO42−

C.     H2PO4 and PO43−

D.     HPO42− only




What is the conjugate base of phenol, \({{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{OH}}\)?

A.     \({{\text{C}}_6}{\text{H}}_4^ - \)–OH

B.     \({{\text{C}}_6}{{\text{H}}_5}\)–\(\mathop {\text{O}}\limits^ +  {{\text{H}}_2}\)

C.     \({{\text{C}}_6}{{\text{H}}_5}\)–\({{\text{O}}^ - }\)

D.     \({{\text{C}}_6}{\text{H}}_6^ + \)–OH




What are the conjugate acid–base pairs in the following reaction?

\[{\text{HCO}}_3^ - {\text{(aq)}} + {{\text{H}}_2}{\text{O(l)}} \rightleftharpoons {\text{O}}{{\text{H}}^ - }{\text{(aq)}} + {{\text{H}}_2}{\text{C}}{{\text{O}}_3}{\text{(aq)}}\]

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If \({\text{20 c}}{{\text{m}}^{\text{3}}}\) samples of \({\text{0.1 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) solutions of the acids below are taken, which acid would require a different volume of \({\text{0.1 mol}}\,{\text{d}}{{\text{m}}^{ - 3}}\) sodium hydroxide for complete neutralization?

A.     Nitric acid

B.     Sulfuric acid

C.     Ethanoic acid

D.     Hydrochloric acid




Which group of three compounds contains only weak acids and bases?

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Which salts will dissolve in water to give solutions with a pH above 7?

I.     \({\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}\)

II.     \({\text{C}}{{\text{H}}_{\text{3}}}{\text{COONa}}\)

III.     \({\text{N}}{{\text{a}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\)

 

A.     I and II only

B.     I and III only

C.     II and III only

D.     I, II and III




What describes HPO42−?

A.     Amphiprotic but not amphoteric

B.     Amphoteric but not amphiprotic

C.     Amphiprotic and amphoteric

D.     Neither amphiprotic nor amphoteric