What is the Ka of a 0.0675 M solution of carbonic acid
(H2CO3) with a pH of 5.19?
Ka = [ ? ] x 10
Help ASAP

The Ka is 6.183 * 10^-10

Explanation:

The first thing to do here is to write the dissolution equation of carbonic acid in water.

H2CO3 + H20 ———> H30+ + HCO3-

After writing this, the next thing is to write the expression for Ka

Mathematically that would be ;

Ka = [H30+][HCO3-]/[H2CO3]

Next thing is to set up an ICE table

ICE table stands for initial, change and equilibrium.

For clarity sake, please check attachment for the ICE table for this chemical reaction

Mathematically by definition;

pH = -log [H3O+]

From the question, we were made to know that the pH is 5.19

Hence;

5.19 = -log [H3O+]

-5.19 = log [H30+]

[H3O+] = 10^-(5.19)

[H3O+] = 6.46 * 10^-6 M

So how does this relate to the ICE table?

From the ICE table, we can see that the equilibrium concentration of the hydroxonium ion equals x.

This means that the equilibrium concentration of the hydroxonium ion [H3O+] , demoted as x = 6.46 * 10^-6 M

Now according to the Ka equation;

Kindly recall that;

Ka = [H30+][HCO3-]/[H2CO3]

Now, using their equilibrium concentrations;

Ka = (x)(x)/(0.0675-x)

Ka= x^2/(0.0675-x)

Kindly substitute 6.46 * 10^-6 for x

Ka = (6.46 * 10^-6)^2/(0.0675-(6.46 * 10^-6)

Ka = 6.183 * 10^-10

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms