What Is Chemical Effects of Electric Current Class 8 Notes Explained

Understanding Chemical Effects of Electric Current

Electric current is the flow of electric charge through a conductor. When it passes through certain liquids called electrolytes, it causes chemical changes. This phenomenon is known as the chemical effects of electric current.

In Class 8 NCERT Science, this chapter explains how electric current can decompose compounds, cause deposition of metals, and produce gases. These changes happen due to the movement of ions in the electrolyte.

Key points:

• Electric current causes chemical reactions in electrolytes.
• These reactions are used in processes like electroplating and electrolysis.
• Understanding this helps explain many practical applications in daily life.

What Is Electrolysis? Definition and Process

Electrolysis is the process of breaking down a compound into its elements using electric current. It occurs in a liquid called an electrolyte, which contains ions.

How electrolysis works:

• Two electrodes (anode and cathode) are placed in the electrolyte.
• When electric current flows, positive ions move towards the cathode, and negative ions move towards the anode.
• At the electrodes, chemical reactions occur, releasing elements or gases.

For example, electrolysis of water splits it into hydrogen and oxygen gases:

$$ 2H_2O(l) \xrightarrow{electric\ current} 2H_2(g) + O_2(g) $$

Electrolysis is important in industries and helps us understand the chemical effects of electric current.

Electrodes and Their Roles in Chemical Effects

In chemical effects of electric current, electrodes are conductors that allow current to enter or leave the electrolyte. There are two types:

• Anode: Positive electrode where oxidation occurs.
• Cathode: Negative electrode where reduction occurs.

The type of electrode affects the products formed during electrolysis. For example, in copper sulfate solution:

Thus, electrodes are crucial for chemical changes caused by electric current.

Applications of Chemical Effects of Electric Current

Chemical effects of electric current have many practical uses:

• Electroplating: Coating a metal object with a thin layer of another metal to prevent rust or improve appearance. For example, silver plating on jewellery.
• Purification of metals: Impure metals like copper are purified by electrolysis.
• Extraction of metals: Some metals are extracted from their ores using electrolysis.
• Production of gases: Electrolysis of water produces hydrogen and oxygen gases.

These applications show how chemical effects are important in industries and everyday life.

Key Formulas and Worked Example

To understand chemical effects, knowing some basic formulas and examples helps.

Example: Electrolysis of molten sodium chloride (NaCl):

At cathode: $Na^+ + e^- \rightarrow Na$ (Sodium metal is formed)

At anode: $2Cl^- \rightarrow Cl_2 + 2e^-$ (Chlorine gas is released)

Worked Example: If 1 mole of electrons passes through molten NaCl, how many moles of sodium metal are formed?

Since 1 mole of electrons deposits 1 mole of sodium ions, 1 mole of sodium metal is formed.

Understanding such reactions helps solve numerical problems in exams.

Difference Between Electrical and Chemical Effects of Electric Current

It's important to distinguish between the two main effects of electric current:

Both effects are studied in Class 8 Science, but this chapter focuses on the chemical effects and their applications.