96. Lime juice is among the most acidic of the fruit juices, with a pH of 1.92. If the acidity is...

Question

96. Lime juice is among the most acidic of the fruit juices, with a pH of 1.92. If the acidity is due
to citric acid, which we can abbreviate as H3Cit, what is the ratio of each of the following:
[Cit -3]
--------- =
[H3Cit]
[ H 2Cit - ]
---------- =
[ HCit 2- ]
H3Cit ===== H+
+ H2Cit - Ka 1 = 8.4 x 10 - 4
H2Cit -
===== H+
+ HCit -2 K a 2 = 1.8 x 10 - 5
HCit - 2 ==== H +
+ Cit - 3 K a 3 = 4.0 x 10 - 6

Answer 1

This question is actually testing your understanding of pH and Ka.

 

The concentration of H⁺ can be calculated based on the definition of pH. Combining with the definition of Ka, you can get the ratio of any two different ions (H₃Cit, H₂Cit^-, HCit^2- and Cit^3-).

 

Answer: Cit^3-/H₃Cit = 3.48*10^-8

 

H₂Cit^-/HCit^2- = 667.9247