Question

Calculate the [OH−] of each aqueous solution with the following [H3O+].

Part A

coffee, 1.0×10⁻⁵ M

Express your answer using two significant figures.

[OH−] =

  M  

Part B

soap, 1.0×10⁻⁸ M

Express your answer using two significant figures.

[OH−] =

  M  

Part C

cleanser, 4.9×10⁻¹⁰ M

Express your answer using two significant figures.

[OH−] =

  M  

Part D

lemon juice, 2.5×10⁻² M

Express your answer using two significant figures.

[OH−] =

  M  

Answer 1

Sol :-

Ionic product of water (K_w) = [H₃O⁺].[OH^-]

K_w of water at 25 ⁰C = 1.0 x 10^-14 M²

again,

[H₃O⁺] = K_w/[OH^-]

[OH^-] = 1.0 x 10^-14 M² / [H₃O⁺]

Part. (A). [H₃O⁺] = 1.0 x 10^-5 M

[OH^-] = 1.0 x 10^-14 M² / 1.0 x 10^-5 M

[OH^-] = 1.0 x 10^-9 M

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Part. (B). [H₃O⁺] = 1.0 x 10^-8 M

[OH^-] = 1.0 x 10^-14 M² / 1.0 x 10^-8 M

[OH^-] = 1.0 x 10^-6 M

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Part. (C). [H₃O⁺] = 4.9 x 10^-10 M

[OH^-] = 1.0 x 10^-14 M² / 4.9 x 10^-10 M

[OH^-] = 2.0 x 10^-5 M

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Part. (D). [H₃O⁺] = 2.5×10⁻² M

[OH^-] = 1.0 x 10^-14 M² / 2.5×10⁻² M

[OH^-] = 4.0 x 10^-13 M

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