Question

Calculate the$pH$of orange juice in which hydronium ion conc. $\left( {{H_{3}}{O^ + }} \right)\;is{\text{ }}2\; \times \;{10^{ - 8\;}}mol/l\;.$

Answer 1

To calculate the $pH$ of a orange juice , we have to used the formula: $pH$=$- lo{g_{10}}\left[ {{H_3}{O^ + }} \right]$. As per equation, the $pH$ of a solution is the negative of base $10$logarithm of hydronium ion concentration in a solution. The concentration of hydronium ions in an aqueous solution can provide information about the acidic, basic, or neutral nature of a solution. At room temperature, the pH of neutral water is equal to $7$.

Complete step by step answer:
$pH$ stands for potential of hydrogen and $pH$ scale is a logarithmic scale that is used to measure the acidity or the basicity of a substance. The range of the scale varies from $0{\text{ }}to{\text{ }}14$. Solutions having a value of $pH$ ranging$\;0{\text{ }}to{\text{ }}7$on $pH$ scale are known as acidic and for the value of $pH$ ranging $7{\text{ }}to{\text{ }}14$on $pH$ scale are called basic solutions and the Solutions having the value of pH equal to $7$ on $pH$ scale are termed as neutral solutions.
When we determine the $pH$ value of orange juice, we need to know the concentration of hydronium ions in moles per liter (molarity) of the solution.
To calculate the $pH$ of a solution, use the equation $pH$= $- lo{g_{10}}\left[ {{H_3}{O^ + }} \right]$
Given,
Concentration of Hydronium Ion \left( {{H_3}{O^ + }} \right)$$$$ = 2 \times {10^{ - 8}}moles/l
$\left[ {{H_3}{O^ + }} \right]$ $= 2 \times {10^{ - 8}}$
$pH$=$- lo{g_{10}}\left[ {{H_3}{O^ + }} \right]$
$pH = - lo{g_{10}}\left[ {2 \times {{10}^{ - 8}}} \right]$
By solving the log
$\therefore$ we know that, ${\log _{10}}10 = 1$ and $log2 = 0.3010$
$pH = - \left[ {lo{g_{10}}(2) + {{\log }_{10}}({{10}^{ - 8}})} \right]$
$pH = - \left[ {0.3010 - 8} \right]$
$pH = 8 - 0.3010$
$pH = 7.6990$
Note: $pH\;$ measurement is used in a wide variety of applications: agriculture, wastewater treatment, industrial processes, environmental monitoring, and in research and development. In our real life $pH\;$ is important because substances such as our stomach acids tend to be at certain $pH$ in order to work properly and it must be at certain levels in order for living organisms to survive.