Calculate the concentration of H_(3)O^(+) ions in a mixture of 0.02 M acetic acidand0.2 M sodiumacetate. Given that the ionization constant (K_(a)) foracetic acid is 1.8xx10^(-5).

Calculate the concentration of H_(3)O^(+) ions in a mixture of 0.02 M

1.	Calculate the concentration of H_(3)O^(+) ions in a mixture of 0.02 M acetic acidand0.2 M sodiumacetate. Given that the ionization constant (K_(a)) foracetic acid is 1.8xx10^(-5).
Answer» Solution :`{:(,CH_(3)CO OH +H_(2)O,hArr,CH_(3)CO O^(-) +, H_(3)O^(+),),("Initial moles",0.02,,0,0,),("Moles at eqm.",0.02-x,,x,x,),(,CH_(3)CO ONa,rarr,0,0,),("Initial moles",0.2,,0,0,),("Moles at eqm.",0,,0.2,0.2,),(,,,,,):}` THUS, in the mixture solution, `[CH_(3)CO O^(-)]=0.2+x~=0.2 M (CH_(3)CO O^(-)" are obtained mainly from" CH_(3)CO ONa," therefore," x ltlt 0.2)` `[CH_(3)CO OH ] = 0.02 - x ~= 0.02 M` `K_(a)=([CH_(3)CO O^(-)][H_(3)O^(+)])/([CH_(3)CO OH]), i.e., 1.8xx10^(-5)=(0.2xx[H_(3)O^(+)])/(0.02)` or`[H_(3)O^(+)]=(1.8xx10^(-5)xx0.02)/(0.2) = 1.8xx10^(-6)M` Note. The GIVEN mixture is a buffer as discussed LATER inArt. 7.32 .