MYP 10 Chemistry 2013-14
Acids and Bases Worksheet 1
Name: _________________________________ ( )
Class: _________ Date: _____________
_________________________________________________________________________________
1. Identify each of the compounds below as an acid or base. Which are conjugate pairs?
(a)
(b)
(c)
(d)
(e)
H3O+ (aq) + NH3(aq)
H2O(l) + NH4+ (aq)
HCN(aq) + H2O(l)
H3O+(aq) + CN- (aq)
CH3COOH(aq) + NH3(aq)
NH4+(aq) + CH3COO-(aq)
CO32-(aq) + H3O+ (aq)
H2O(l) + HCO3-(aq)
NH4+(aq) + NO2-(aq)
HNO2(aq) + NH3(aq)
2. Which of the following bases in the given base pairs will be the strongest?
(a) Cl- and HCO3(b) HSO3- and NO3(c) C2H3O2- and ClO43. Sodium hydrogencarbonate dissolves in water forming an alkaline solution according to the following
ionic equilibrium:
HCO3-(aq) + H2O(l)
H2CO3(aq) + OH-(aq)
(a) Why is the solution alkaline?
(b) Using the Bronsted-Lowry theory, state, with a brief explanation, whether the HCO3- ion is behaving as
an acid or as a base.
(c) Identify the conjugate base of carbonic acid, H2CO3.
[SL paper 2, May 01]
4. Which of the following species can act as both a Bronsted-Lowry acid and base in aqueous solution?
A.
B.
C.
D.
CH3COOH
NO3H2PO4OH-
5. Choosing suitable examples from the following: NH3, O2- , Cu2+ , OH-, NH2-, H2O
(a) Bronsted-Lowry acid
(b) Lewis acid
(c) Conjugate acid-base pair (Identify both acid-base pairs)
MYP 10 Chemistry 2013-14
Acids and Bases Worksheet 2
Name: _________________________________ ( )
Class: _________ Date: _____________
_________________________________________________________________________________
1. Carbonic acid (H2CO3) is described as a weak acid and hydrochloric acid is described as a strong acid.
(a) Explain, with the help of equations, what is meant by strong and weak acid using the above acids as
examples.
(b) Outline two ways, other than using pH, in which you could distinguish between carbonic acid and
hydrochloric acid of the same concentration.
(c) A solution of hydrochloric acid, HCl(aq) has a pH of 1 and a solution of carbonic acid, H2CO3(aq) has
a pH of 5. Determine the ratio of hydrogen ion concentrations in these solutions. [SL paper 2, Nov 02]
2(a) What is the pH of a solution if the concentration of H3O+ is
(i)
0.003 moldm-3?
(ii)
1.5 x 10-6 moldm-3?
(b) What is the concentration of H3O+ of a solution that has a pH = 5.4 ?
(c) Calculate the concentration of H3O+ when the concentration of OH- is 3.2 x 10-3 moldm-3.
3. A solution of 0.000 100 moldm-3 hydrochloric acid has a pH of 4.00, whereas a solution of
0.100 moldm-3 ethanoic acid has a pH of 2.88. Explain what these values tell you about the usefulness of
pH as a measure of acid strength.
4. 25.0 cm3 of hydrochloric acid of known concentration is titrated with a dilute sodium hydroxide solution.
The pH of the mixture is measured continuously as shown in the graph below:
(a) From the graph, determine the pH after 10.0cm3 of sodium hydroxide solution is added.
(b) Determine the concentration of hydrochloric acid before titration and state its units.
(c) From the graph, determine the volume of sodium hydroxide solution required to neutralise the
hydrochloric acid.
(d) Calculate the concentration of the sodium hydroxide and state its units.
[SL paper 2, Nov 00]
*5. A solution of 0.2 moldm-3 HCl has a pH of 0.7. Of this solution, 25.0 cm3 is taken and made up to
250cm3 with distilled water in a volumetric flask to form solution X. 10.0 cm3 of solution X is taken
and made up to a total volume of 1.00 moldm-3 with distilled water in a volumetric flask; this is
solution Y. Work out the pH for each solution.
6(a) The equation of two acid-base reactions are given below.
Reaction A NH3(aq) + H2O(l)
NH4+(aq) + OH-(aq)
The reaction mixture in A consists mainly of reactants because the equilibrium lies to the left.
Reaction B
NH2- (aq) + H2O(l)
NH3(aq) + OH-(aq)
The reaction mixture B cnsists mainly of product because the equilibrium lies to the right.
(i)
For ecah of the reactions A and B, deduce whether water is acting as an acid or a base and
explain your answer.
(ii)
In reaction B, identify the stronger base, NH2- or OH- and explain your answer.
(iii) In reactions A and B, identify the stronger acid, NH4+ or NH3 (underlined) and explain your
answer.
(b) Describe two differet experimental methods to distinguish between aqueouos solutions of a strong base
and a weak base.
(c)(i) Define a Lewis acid and state an example that it is not a Bronsted-Lowry acid.
(ii) Draw structural formulas to represent the reaction between the Lewis acid named in (c)(i) and a Lewis
base and identify the nature of the bond formed in the product.
[SL paper 2, Nov 09]
?*6(a) Define the term buffer solution.
(b) State and explain whether each of the following solutions will form a buffer solution.
(i) A 1.0 dm3 solution containing 0.10 mol NH3 and 0.20 mol HCl
(ii) A 1.0 dm3 solution containing 0.20 mol NH3 and 0.10 mol HCl
[SL paper 2, Nov 03]