Lemon juice has a pH = 2.1 . If all the acid in lemon is citric acid (H "Cit." hArr H^(+)+"Cit"^(-1)) and K_(a) for citric acid is 8.4xx10^(-4) mole/litre, what is the concentration of citric acid in lemon juice ?

Lemon juice has a pH = 2.1 . If all the acid in lemon is citric acid (

1.	Lemon juice has a pH = 2.1 . If all the acid in lemon is citric acid (H "Cit." hArr H^(+)+"Cit"^(-1)) and K_(a) for citric acid is 8.4xx10^(-4) mole/litre, what is the concentration of citric acid in lemon juice ?
Answer» SOLUTION : `pH = 2.1 , i.e., - log [H^(+)]=2.1 or log [H^(+)]= - 2.1 = bar(3). 9 or [H^(+)] = 7.943xx10^(-3)` `"HCit"HARR H^(+) + "Cit"^(-1)` `K_(a) = ([H^(+)] [Cit^(-1)])/(["H Cit"])` `8.4xx10^(-4)=(7.943xx10^(-3))(7.943xx10^(-3))/(["H Cit"]) or ["H Cit" ] = 7.5 xx 10^(-2)M`