Question

pH of tomato juice is 4.4. Then concentration of ${ H }_{ 3 }{ O }^{ + }$ will be?
(a) $39\times { 10 }^{ -4 }$
(b) $3.9\times { 10 }^{ -5 }$
(c) $3.9\times { 10 }^{ -4 }$
(d) $3.9\times { 10 }^{ 5 }$

Answer 1

Hint: The concept of pH was first introduced by the Danish chemist Soren Peder Lauritz Sorensen at the Carlsberg. pH stands for “power of hydrogen” which means pH is the measurement of hydrogen ion concentration in a liquid solution. This activity is directly connected to its acidic, basic and neutral characteristics.

Complete step by step answer:
The pH is the scale used to specify how acidic or basic a water based solution is. Acidic solutions have a lower pH, while basic solutions have a higher pH, at room temperature , pure water is neither acidic nor basic and has a pH of 7. pH is the measure of hydrogen ion concentration in water based solution. Very strong acids might have a negative pH, while very strong bases might have a pH greater than 14.
Let us see how pH is measured.
pH measurements can be made using litmus paper. Most of the indicators and pH papers are useful only to tell whether a substance is acid or base. A universal indicator is a mixture of indicator solutions intended to provide a color change over a pH range of 2 to 10. More accurate measurements are made using primary standards to calibrate a glass electrode and pH meter. An example of a standard electrode is silver chloride.
I think now you have a complete idea on pH right? Now, let us try to solve it!
From, the given question,
pH of tomato juice = 4.4
Now, by using the $pH$ formula
pH = -log\[ { H }^{ + }\]
Let us calculate the concentration of ${ H }_{ 3 }{ O }^{ + }$.
\[{ H }_{ 3 }{ O }^{ + }\] = antilog4.4
\[{ H }_{ 3 }{ O }^{ + } =3.981\times { 10 }^{ -5 }\]
Therefore, the concentration of \[{ H }_{ 3 }{ O }^{ + } is 3.9\times { 10 }^{ -5}\]. Hence, option B is the required answer.

Note: pH is a very useful and popular scale. It has great contribution in agriculture, dental condition, digestion, pisciculture, wastewater treatment, industrial process etc.