Solveeit Logo
Login

Question

Question: The concentration of hydrogen ions in a sample of soft drink is \[3.8 \times {10^{ - 3}}M\]. What is...

The concentration of hydrogen ions in a sample of soft drink is 3.8×10−3M3.8 \times {10^{ - 3}}M. What is its pH? :-

Explanation

Solution

Using the equation, pH=−log⁡[H+]pH = - \log \left[ {{H^ + }} \right], we can solve for pH of the solution sample as, ⇒  pH=−log⁡10[H+] \Rightarrow \;pH = - {\log _{10}}\left[ {{H^ + }} \right] or, we can also write,
[H+]=10−pH.\left[ {{H^ + }} \right] = 10 - pH.
by exponentiating both sides with base 10 to "undo" the common logarithm. The pH of Solution can be calculated easily and we can easily get our final result.
⇒  pH+pOH=14\Rightarrow \;pH + pOH = 14

Complete step by step answer:
In the above question, concentration of hydrogen ion in a sample of soft drink is given to be 3.8×10−33.8 \times {10^{ - 3}}M, we have to find the pH of the solution;
First, let’s know what the pH of a solution means.
The pH of a solution is a measure of the molar concentration of hydrogen ions in the solution and as such is a measure of the acidity or basicity of the solution.
The pH scale is said to range from 0 to 14, Anything below 7.0 is acidic, and anything above 7.0 is alkaline or basic.
If the pH is about 7, the solution is neutral.
pH is defined as : −log⁡10  of  [H+] - {\log _{10}}\;of\;\left[ {{H^ + }} \right]
pH=−log⁡10[H+]pH = - {\log _{10}}\left[ {{H^ + }} \right]
So,  pH=−log⁡10×3.8×10−3So,\;pH = - {\log _{10}} \times 3.8 \times {10^{ - 3}}
=−(3)log⁡10−log⁡3.8= - (3){\log _{10}} - \log 3.8
As  log⁡10  is  1  we  get;As\;{\log _{10}}\;is\;1\;we\;get;
pH=−(−3)×1−log⁡(3.8)pH = - ( - 3) \times 1 - \log \left( {3.8} \right)
=(3×1)−log⁡(3.8)= \left( {3 \times 1} \right) - \log \left( {3.8} \right) [∵    log⁡(3.8=0.57%)]\left[ {\because \;\;\log \left( {3.8 = 0.57\% } \right)} \right]
=3−0.5798= 3 - 0.5798
⇒  pH=2.42\Rightarrow \;pH = 2.42
∴\therefore pH of the solution is 2.42

Note:
The letters pH stand for potential of hydrogen, since pH is effectively a measure of the concentration of hydrogen ions (that is, protons) in a substance.
The pH scale is a measure of the acidity or alkalinity (basicity) or a solution. The scale runs from 0 to 14, with acids having a pH less than 7, 7 being neutral, and bases having a pH higher than 7. Acids and bases react with each other in what is called a neutralization reaction.