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Acid/Base Equilibrium - Weak Acids/Bases 1. Calculate the [HClO] in a solution i

ID: 896837 • Letter: A

Question

Acid/Base Equilibrium - Weak Acids/Bases

1. Calculate the [HClO] in a solution if it has a pH 5.35. (Constant = Ka=3.50×10-8 )

HClO = OCl- + H+

_______ M

2.Estimate the initial [HClO] in an aqueous solution in which the [OCl-] is 0.0000167 M at equilibrium (make an approximate calculation assuming that initial concentration is equal to the equilibrium concentration).

(Constant = Ka=3.50×10-8 )

HClO = OCl- + H+

____________ M

3. Calculate the [OCl-] of a 2.27×10-3 M solution of the weak acid HClO (make an approximate calculation assuming that initial concentration is equal to the equilibrium concentration). Round your answer to 3 significant digits. (Constant = Ka=3.50×10-8 )

HClO = OCl- + H+

___________ M

1. Calculate the [HClO] in a solution if it has a pH 5.35. (Constant = Ka=3.50×10-8 )

HClO = OCl- + H+

_______ M

2.Estimate the initial [HClO] in an aqueous solution in which the [OCl-] is 0.0000167 M at equilibrium (make an approximate calculation assuming that initial concentration is equal to the equilibrium concentration).

(Constant = Ka=3.50×10-8 )

HClO = OCl- + H+

____________ M

3. Calculate the [OCl-] of a 2.27×10-3 M solution of the weak acid HClO (make an approximate calculation assuming that initial concentration is equal to the equilibrium concentration). Round your answer to 3 significant digits. (Constant = Ka=3.50×10-8 )

HClO = OCl- + H+

___________ M

Explanation / Answer

1. Calculate the [HClO] in a solution if it has a pH 5.35. (Constant = Ka=3.50×10-8 )

HClO = OCl- + H+

Solution :-

pH is given therefore using the pH lets calculate the concentration of the [H3O+]

pH= -log [H+]

[H+] = antilog [-pH]

        = antilog [-5.35]

        = 4.467*10^-7 M

[H+] = [OCl-] = 4.467*10^-6 M

Ka= [H+][ClO-] /[HClO]

Therefore

[HClO] = [H+][ClO-] / ka

             = [4.467*10^-6] [4.467*10^-6] / 3.50*10^-8

            = 5.70*10^-4 M

Therefore the [HClO] = 5.70*10^-4 M

2) Estimate the initial [HClO] in an aqueous solution in which the [OCl-] is 0.0000167 M at equilibrium (make an approximate calculation assuming that initial concentration is equal to the equilibrium concentration).

(Constant = Ka=3.50×10-8 )

Solution :- [H+] = [OCl-] = 1.67*10^-5 M

Ka= [H+][ClO-] /[HClO]

Therefore

[HClO] = [H+][ClO-] / ka

             = [1.67*10^-5] [1.67*10^-5] / 3.50*10^-8

            = 7.97*10^-3 M

Therefore the [HClO] = 7.97*10^-3 M

3) Calculate the [OCl-] of a 2.27×10-3 M solution of the weak acid HClO (make an approximate calculation assuming that initial concentration is equal to the equilibrium concentration). Round your answer to 3 significant digits. (Constant = Ka=3.50×10-8 )

Solution :-

Ka= [H+][ClO-] /[HClO]

3.50 *10^-8 = [x][x]/[2.27*10^-3]

3.50 *10^-8*[2.27*10^-3] = x^2

7.945*10^-11 =x^2

Taking square root of both sides we get

8.91*10^-6 M= x = [OCl-]

Therefore the concentration of the [OCl-]= 8.91*10^-6 M

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