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# The electro chemical equivalent of a substance is numerically equal to the mass of the substance deposited if current I flow through the electrolyte for $0.25$ seconds. The value of I is ____.A. $1A$ B. $2A$C. $3A$D. $4A$

Last updated date: 15th Sep 2024
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Hint: The interrelating study of electricity and chemical reactions is known as electrochemistry. In electrochemistry the movement of electrons in a redox reaction determines the flow of current or the charge per unit time.

The study of establishing relation between electricity and the chemical reactions is known as electrochemistry. It basically tells that electricity is generated from the movement of electrons in a chemical redox reaction. Redox reaction means oxidation – reduction reaction, in which both oxidation and reduction takes place.
A term electrochemical equivalent is defined for chemical reactions to form a relation between the charge and mass. The mass transported of an element by the electric charge of one coulomb is known as electrochemical equivalent. It is basically denoted as $Z$ . In laboratories the measurement of electrochemical equivalent is done with the help of voltmeter.
The formula for electrochemical equivalent is as follows:
$Z = \dfrac{m}{q}$ -------------(1)
Where, $Z$ is the electrochemical equivalent,
$m$ is the mass of element and
$q$ is denoted for the charge (in coulombs).
In this problem we have given that the electrochemical equivalent and the mass of substance are numerically equal.
$\Rightarrow Z = m$
Using this condition in the equation (1) we get,
$\begin{gathered} 1 = \dfrac{1}{q} \\ \Rightarrow q = 1C \\ \end{gathered}$
The overall charge obtained is one coulomb.
And we know that charge per unit time is known as current, therefore $i = \dfrac{q}{t}$ , where $i$ is the current and $t$ is the time taken.
The current flows through the electrolyte for $0.25\sec$
$\Rightarrow t = 0.25\sec$ and previously we calculated $q = 1C$. So put all these values in the current formula.
$\Rightarrow i = \dfrac{q}{t} = \dfrac{1}{{0.25}} = 4{\text{A}}$
Hence the value of I is $4{\text{A}}$ .

So, the correct answer is Option D .

Note:
The other definition for the electrochemical equivalent is that the mass of substance deposited on the electrode when one coulomb of charge or we can say one ampere current for one second is passed through the electrolytic solution.