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Iodic acid and sulfamic acid are monoprotic acids - HSC - SSCE Chemistry - Question 28 - 2024 - Paper 1
Question 28
Iodic acid and sulfamic acid are monoprotic acids. A 0.100 mol L⁻¹ solution of iodic acid has a pH of 1.151, as does a 0.120 mol L⁻¹ solution of sulfamic acid. Show... show full transcript
Worked Solution & Example Answer:Iodic acid and sulfamic acid are monoprotic acids - HSC - SSCE Chemistry - Question 28 - 2024 - Paper 1
Step 1
Show that neither iodic acid nor sulfamic acid dissociates completely in water
Answer
To demonstrate that neither iodic acid nor sulfamic acid dissociates completely in water, we need to determine the concentration of hydrogen ions using the pH provided for iodic acid. The concentration of hydrogen ions can be calculated as follows:
Since the concentration of hydrogen ions (0.0706 mol L⁻¹) is less than the concentration of iodic acid (0.100 mol L⁻¹), it indicates that iodic acid does not completely dissociate in solution.
A similar calculation can be made for sulfamic acid:
For the 0.120 mol L⁻¹ solution, the concentration of hydrogen ions would also be computed:
Assuming the pH is the same (1.151):
Again, since 0.0706 mol L⁻¹ is less than 0.120 mol L⁻¹, sulfamic acid also does not completely dissociate in solution.
Step 2
Determine which is the stronger acid
Answer
To determine which acid is stronger, we can compare the concentrations of hydrogen ions produced by each acid.
Iodic acid results in a pH of 1.151 for a 0.100 mol L⁻¹ solution, producing 0.0706 mol L⁻¹ of hydrogen ions.
Sulfamic acid, having the same pH but in a 0.120 mol L⁻¹ solution, also produces 0.0706 mol L⁻¹ of hydrogen ions. However, since sulfuric acid had a higher concentration and also yields the same , this signifies that iodic acid must dissociate to a greater extent compared to sulfamic acid at such concentrations. Thus, iodic acid is the stronger acid.