Question

To learn how to calculate ion concentrations in an aqueous solution of a strong diprotic acid.

Sulfuric acid, H2SO4, is a strong acid. Its complete dissociation in aqueous solution is represented as

H2SO4?H++HSO4?

A HSO4? anion can dissociate further by

HSO4??H++SO42?

but the extent of dissociation is considerably less than 100%. The equilibrium constant for the second dissociation step is expressed as

Ka2=[H+][SO42?][HSO4?]=0.012

Part A

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.

[H+] =

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Part B

Calculate the concentration of SO42? ions in a 0.010 M aqueous solution of sulfuric acid.

Express your answer to four decimal places and include the appropriate units.

[SO42?] =

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Part C

Calculate the concentration of HSO4? ions in a 0.010 M aqueous solution of sulfuric acid.

Express your answer to two significant figures and include the appropriate units.

[HSO4?] =

Answer 1

1.0x10^-2M solution of H2SO4.

Sulfuric acid is a strong acid for it's first dissociation, which means it will dissociate completely to give us H+ and HSO4-. HSO4- will also disassociate, but not completely. We will find out how much:

initial species in solution: 1.0x10^-2M H+, 1.0x10^-2M HSO4-, H2O.

Since the initial concentration of SO4 2- is 0, we know that the equilibrium will progress in the forward direction. Let X equal the change in concentration.

..................................... HSO4-.................<--->. H+....................+ SO4 2-
Initial concentration........1.0x10^-2........