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Question: The pH of 0.1 M NaOH is (A) 13 (B) 12 (C) 11 (D) 10...

The pH of 0.1 M NaOH is
(A) 13
(B) 12
(C) 11
(D) 10

Explanation

Solution

pH denotes the ‘potential of Hydrogen’ or ‘power of Hydrogen’. The negative logarithm of the hydrogen ion activity is known as pH.
pH=−log⁡[H+]pH=-\log [{{H}^{+}}]

Complete step by step solution:
-Let us assume that the solution of 0.1M NaOH is a strong base and will produce 0.1mol/L of OH ions in the solutions.
NaOH→Na++OH−NaOH\to N{{a}^{+}}+O{{H}^{-}}
Hence, [OH−]=[NaOH]=0.1M[O{{H}^{-}}]=[NaOH]=0.1M
pOH=−log⁡[1×10−1]pOH=-\log [1\times {{10}^{-1}}]
=−log⁡1+−log⁡10−1=-\log 1+-\log {{10}^{-1}}
=0+(−1)log⁡10=0+1×1=0+1=1=0+(-1)\log 10=0+1\times 1=0+1=1
So, the pOHpOH of 0.1M0.1M solution of NaOHNaOH is 11.
-Now, we know that,
pH+pOH=14pH + pOH = 14
Therefore, we can now calculate the pH of 0.1M of NaOH from the calculated value of pOH and using the above equation,
pH+1=14pH +1 = 14
⇒pH=14−1=13\Rightarrow pH=14-1=13
Therefore, the pHpH of 0.1M0.1M NaOHNaOH solution is 1313.

So, the correct answer is option A.

Note: You should not get confused between the pH and pOH of the solution.
-Both pH and pOH scales determine the measure of the strength of acids and bases between scale 1 to 14.
-pH is an abbreviation for the ‘potential of hydrogen’ while pOHpOH is an abbreviation for the ‘potential of hydroxide’.
-The pH for any aqueous solution is calculated from [H+][{{H}^{+}}] using the formula, pH=−log⁡[H+]pH=-\log [{{H}^{+}}]
The lowercase p indicates ′−log⁡10′'-{{\log }_{10}}' .
The pOH is defined as the negative logarithm of the hydroxide ion and is calculated using the following formula,
pOH=−log⁡[OH−]pOH=-\log [O{{H}^{-}}]
-Based on the equilibrium concentration of H+{{H}^{+}}and OH−O{{H}^{-}}ions in water, the following relationship is true for any aqueous solution at 25∘C25{}^\circ C.
pH+pOH=14pH + pOH = 14
-Anything with a pH between 1 to 6 is acidic while anything with the pOH between 1 to 6 is basic.
-Anything with a pH between 8 to 14 is basic while anything with the pOH between 8 to 14 is acidic.
-Anything with a pH and pOH 7 is neutral.
-If an acid has a pH between 1 to 3, it is a strong acid, while a base has a pOH between 1 to 3 is a strong base.
-If an acid has a pH between 4 to 6, it is a weak acid, while a base has a pOH between 4 to 6 is a weak base.
-If a base has a pH between 8 to 11, it is a weak base, while an acid has a pOH between 8 to 11 is a weak acid.
-If a base has a pH between 12 to 14, it is a strong base, while an acid has a pOH between 12 to 14 is a strong acid.