Iodic acid and sulfamic acid are monoprotic acids. A 0.100 mol L
Show that neither iodic acid nor sulfamic acid dissociates completely in water, and determine which is the stronger acid. (3 marks)
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Iodic acid and sulfamic acid are monoprotic acids. A 0.100 mol L
Show that neither iodic acid nor sulfamic acid dissociates completely in water, and determine which is the stronger acid. (3 marks)
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→ Calculating the concentration of hydronium ions in solution for a pH of 1.151.
→ As this is less than the concentration of both of the acids, neither acid completely dissociates in water.
→ A smaller concentration of iodic acid (0.100 mol/L compared to 0.120 mol/L sulfamic acid) produces the same pH level. Iodic acid must have a greater extent of ionisation compared to sulfamic acid.
→ Therefore iodic acid is a stronger acid than sulfamic acid.
→ Calculating the concentration of hydronium ions in solution for a pH of 1.151.
→ As this is less than the concentration of both of the acids, neither acid completely dissociates in water.
→ A smaller concentration of iodic acid (0.100 mol/L compared to 0.120 mol/L sulfamic acid) produces the same pH level. Iodic acid must have a greater extent of ionisation compared to sulfamic acid.
→ Therefore iodic acid is a stronger acid than sulfamic acid.
How does diluting a 0.1 M solution of lactic acid,
pH | Percentage ionisation | |
A. | increase | decrease |
B. | increase | increase |
C. | decrease | increase |
D. | decrease | decrease |
→ Ionisation of lactic acid:
→ Adding water decreases
→
→ Overall, the pH increases and the percentage ionisation increases.
Propanoic acid dissociation in water can is represented in the following equation:
Explain how the pH of the propanoic acid solution would change if it was diluted. (3 marks)
→ Propanoic acid only partially ionises in solution and is defined as a weak acid.
→ Any dilution of the acid will result in a decrease of the concentration of all species (including the hydronium ion).
→ According to Le Chatelier, the decreasing concentrations of dissolved species will cause the equilibrium to shift to the right.
→ While this effect causes an increase in ionisation, it is not sufficient to counter the decrease in hydronium ion concentration caused by the original dilution.
→ Since the net effect causes the hydronium ion concentration to decrease, the solution will become less acidic and the pH will increase.
→ Propanoic acid only partially ionises in solution and is defined as a weak acid.
→ Any dilution of the acid will result in a decrease of the concentration of all species (including the hydronium ion).
→ According to Le Chatelier, the decreasing concentrations of dissolved species will cause the equilibrium to shift to the right.
→ While this effect causes an increase in ionisation, it is not sufficient to counter the decrease in hydronium ion concentration caused by the original dilution.
→ Since the net effect causes the hydronium ion concentration to decrease, the solution will become less acidic and the pH will increase.
Which beaker contains a concentrated strong acid?
→ A concentrated strong acid will have a greater number of molecules per unit volume, and completely dissociate in water.
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a.
→ Sodium acetate is a basic salt.
→ Acetate is a strong base that accepts a proton, producing hydroxide.
→ The presence of
b.
→ The
→ By Le Chatelier’s principle, this will subsequently move the reaction to the left to increase the
a.
→ Sodium acetate is a basic salt.
→ Acetate is a strong base that accepts a proton, producing hydroxide.
→ The presence of
b.
→ The
→ By Le Chatelier’s principle, this will subsequently move the reaction to the left to increase the
A solution of sodium hydroxide was titrated against a standardised solution of acetic acid which had a concentration of 0.5020 mol L¯1.
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a.
b.
→ The acetate ion is a weak base.
→ As a result, it has accepted a proton from the water resulting in production of hydroxide ions.
→ Therefore the solution has a pH > 7.
a.
b.
→ The acetate ion is a weak base.
→ As a result, it has accepted a proton from the water resulting in production of hydroxide ions.
→ Therefore the solution has a pH > 7.
The effect of concentration on the pH of acrylic acid
Explain the trends in the graph. Include relevant chemical equations in your answer. (4 marks)
→
→ Acrylic acid, on the other hand, is a weak acid that only partially dissociates in water, resulting in a lower concentration of
→ When the concentration of
→ However, when the concentration of acrylic acid decreases by a factor of 10, its pH increases by less than 1.
→ This is due to the change in pH causing the equilibrium to shift right, producing more
→ At very dilute concentrations, the degree of dissociation of acrylic acid approaches 100% and its pH converges closely to that of
→
→ Acrylic acid, on the other hand, is a weak acid that only partially dissociates in water, resulting in a lower concentration of
→ When the concentration of
→ However, when the concentration of acrylic acid decreases by a factor of 10, its pH increases by less than 1.
→ This is due to the change in pH causing the equilibrium to shift right, producing more
→ At very dilute concentrations, the degree of dissociation of acrylic acid approaches 100% and its pH converges closely to that of
A student makes up a solution of propan-2-amine in water with a concentration of 1.00 mol L ¯1.
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a.
b.
Assume
a.
b.
Assume
An aqueous solution of sodium hydrogen carbonate has a pH greater than 7 .
Which statement best explains this observation?
→
→
→ As a result, this produces
Methanoic acid reacts with aqueous potassium hydroxide. A salt is produced in this reaction.
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a.
b. Potassium methanoate is a basic salt.
This is because the
a.
b. Potassium methanoate is a basic salt.
This is because the