We are being asked to determine the concentration of all species in a 0.180 M solution of H2CO3
Since H2CO3 has a low Ka value, it’s a weak acid. Remember that weak acids partially dissociate in water and that acids donate H+ to the base (water in this case). The dissociation of H2CO3 is as follows:
H2CO3 (aq) + H2O (l) ⇌ H3O+(aq) + HCO3- (aq); Ka = 4.2x10-7
From this, we can construct an ICE table. Remember that liquids are ignored in the ICE table.
The Ka expression for H2CO3 is:
Note that each concentration is raised by the stoichiometric coefficient: [H2CO3], [H3O+] and [HCO3-] are raised to 1.
Calculate the concentration of all species in a 0.180 M solution of H2CO3.
[H2CO3], [HCO−3], [CO2−3], [H3O+], [OH−] =
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