What is the equilibrium constant of citric acid?

Answer 1

Citric acid falls into the category of polyprotic acids, which are acids that have more than one acidic hydrogen that can react with water to produce the hydronium ion, #"H"_3^(+)"O"#.

Citric acid's molecular formula is #"C"_6"H"_8"O"_7#, and it's known as a weak organic acid. CItric acid is actually a triprotic acid, which means it has 3 acidic hydrogen atoms in its structure, as you can see below:

When placed in water, citric acid will ionize in a step-wise manner

#C_6H_8O_(7(aq)) + H_2O_((l)) rightleftharpoons C_6H_7O_(7(aq))^(-) + H_3^(+)O_((aq))# (1)

#C_6H_7O_(7(aq))^(-) + H_2O_((l)) rightleftharpoons C_6H_6O_(7(aq))^(2-) + H_3^(+)O_((aq))# (2)

#C_6H_6O_(7(aq))^(2-) + H_2O_((l)) rightleftharpoons C_6H_5O_(7(aq))^(3-) + H_3^(+)O_((aq))# (3)

For each of these three steps we have a different value for the acid's dissociation constant, #"K"_"a"#. Thus,

Step (1): #"K"_"a1" = 7.5 * 10^(-4)#

Step (2): #"K"_"a2" = 1.7 * 10^(-5)#

Step (3): #"K"_"a3" = 4.0 * 10^(-7)#

Notice that all three dissociation constants are smaller than 1, which is characteristic of a weak acid. Another interesting observation is that the dissociation constant for step (3) is very, very small, which means that the number of acid molecules that undergo ionization in this stage is, for all intended purposes, zero.

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Answer 2

The equilibrium constant of citric acid, represented as ( K_a ), depends on the specific reaction involving citric acid. Citric acid can undergo multiple reactions, each with its own equilibrium constant. Therefore, without specifying the reaction involving citric acid, it is not possible to provide a single equilibrium constant.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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