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Question: The \(pH\) of \({10^{ - 4}}M{\text{ }}KOH\) solution will be:...

The pHpH of 10−4M KOH{10^{ - 4}}M{\text{ }}KOH solution will be:

Explanation

Solution

pHpH is a scale which is used to specify the acidity or basicity of a solution. Acidic solutions are measured to have lower pHpH than basic solutions and it is measured in moles per litremoles{\text{ }}per{\text{ }}litre.

Complete step by step answer:
KOHKOH is an inorganic compound which is commonly known as caustic potash and is a strong base. It appears to be colourless and has many industrial applications such as manufacturing of soaps, acting as an electrolyte in alkaline batteries etc.
We can determine the pHpH of a solution using pHpH to H+{H^ + } formula:
pH=−log⁡([H+])pH = - \log ([{H^ + }])
Given, [KOH]=[OH−]=10−4M[KOH] = [O{H^ - }] = {10^{ - 4}}M
We know that,
[H+][OH−]=1×10−14 [H+]×10−4=1×10−14 [H+]=1×10−1410−4=1×10−4M ∴pH=−log⁡[H+]=−log⁡(1×10−10)=10  [{H^ + }][O{H^ - }] = 1 \times {10^{ - 14}} \\\ [{H^ + }] \times {10^{ - 4}} = 1 \times {10^{ - 14}} \\\ [{H^ + }] = \dfrac{{1 \times {{10}^{ - 14}}}}{{{{10}^{ - 4}}}} = 1 \times {10^{ - 4}}M \\\ \therefore pH = - \log [{H^ + }] = - \log (1 \times {10^{ - 10}}) = 10 \\\

Therefore, the pHpH of 10−4M KOH{10^{ - 4}}M{\text{ }}KOH solution is option (D), 1010.

Note:
The pHpH scale can expand in between 0 to 10{\text{ to }}1 in a linear scale or compact scale into a large scale for comparison. The positive value of the pHpH scale is because of the use of negative log[H+][{H^ + }]. Although, we generally measure pHpH in between 0 to 140{\text{ to }}14, there is no upper limit or lower limit, since pHpH is the concentration of H+{H^ + }.