To learn how to calculate ion concentrations in an aqueous solution of a strong
ID: 948248 • Letter: T
Question
To learn how to calculate ion concentrations in an aqueous solution of a strong diprotic acid. Sulfuric acid, H_2SO_4, is a strong acid. Its complete dissociation in aqueous solution is represented as H_2SO_4 Right arrow H^+ + HSO_4^- A HSO_4^- anion can dissociate further by HSO_4 ^- = H^+ + SO_4^2- but the extent of dissociation is considerably less than 100%. The equilibrium constant for the second dissociation step is expressed as K_a2 = [H^+][SO_4^2-]/[HSO_4^-] = 0.012 Calculate the concentration of H^+ ions in a 0.010 M aqueous solution of sulfuric acid. Express your answer to three decimal places and include the appropriate units. Calculate the concentration of So_4^2- ions in a 0.010 M aqueous solution of sulfuric acid. Express your answer to four decimal places and include the appropriate units. Calculate the concentration of HSO_4^- ions in a 0.010 M aqueous solution of sulfuric acid. Express your answer to two significant figures and include the appropriate units.Explanation / Answer
First dissociation of H2SO4 is 100%.
H2SO4 ---> H+ + HSO4-
0.01 0 0 (before dissociation)
0 0.01 0.01 (after dissociation)
HSO4- ---> H+ + SO4-2
0.01 0 0 (before dissociation)
0.01-x x x (at equilibrium)
Ka2 = [H+][ SO4-2]/[ HSO4-]
or, 0.012 = x2 /(0.01-x)
or, x2 + 0.012x - 0.00012 = 0
x = [-0.012 - {0.0122 - 4*0.00012}]/2
= 0.0065
[H+] = 0.01 + x = 0.01 M + 0.0065 M = 0.0165 M
[SO4-2] = x = 0.0065 M
[HSO4-] = 0.01-x = = 0.01 M - 0.0065 M = 0.0035 M
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