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Acids, Bases and Salts

Acids

An ionic compound or electrovalent compound is formed when metallic atoms donate electrons and non-metallic ions accept electrons.

The word electrolysis is made up of two words electro, which means the flow of electrons, and lysis, which means pertaining to.

Electrolysis is the process by which a chemical compound in the fused state or in aqueous solution undergoes a chemical change on the passage of current.

During electrolysis, a chemical change is brought about by electric energy.

  • Electrolytic cell or voltameter is the vessel consisting of glass, containing two electrodes and an electrolyte.

 
  • The graphite or metal rods through which electric current enters or leaves from an electrolyte are called electrodes.

Therefore, a cathode is the electrode which is connected to the negative terminal of the battery. It has an excess of electrons. An anode is than electrode which is connected to positive terminal of battery. It has deficiency of electrons.

 

Difference between cathode and anode 

Anode Cathode
Connected to positive terminal of the battery Connected to negative terminal of the battery
Migration of anion occurs Migration of cations occurs
Oxidation occurs Reduction occurs


Differences between metallic and electrolytic conductors

Metallic Conductors Electrolytic Conductors
Flow electrons from negative pole to positive pole is responsible for conduction. Flow of ions in solution to the respective electrodes is responsible for conduction.
Shown by metals and alloys Shown by aqueous solution of ionic compounds
Present in both solid and liquid state of metals Present in molten or aqueous solution of the ionic compounds
Physical process Chemical process
  • Electrolyte refers to the compound, which in fused state or in aqueous state conducts electric current so that chemical decomposition of the compound takes place.

The electrolytes which allow a large amount of current to flow through them are called strong electrolytes. The strong electrolytes in fused state are completely dissociated and hence, their ions are free to move in any direction.

Examples include an aqueous solution of mineral acid and caustic alkalis.

The electrolytes which allow a very small amount of current to flow through them are called weak electrolytes. The strong electrolytes in fused state are completely dissociated. Hence, their ions are free to move in any direction.

Examples include aqueous solution of acid and bases.

  • Non-electrolyte is the chemical compound which does not conduct electric current in fused state or in aqueous solution and does not undergo any chemical decomposition.

Examples are carbon tetrachloride, alcohol, ether, pure water, etc.

Differences between strong and weak electrolytes

Strong electrolytes Weak electrolytes
Allows large amount of electricity to flow through them Allows small amount of electricity to flow through them
Good conductors Poor conductors
Undergo complete dissociation in molten or aqueous solution Undergo partial dissociation in molten or aqueous solution
Contain free mobile ions Contains ions and molecules
Examples are HCl, H2SO4, HNO3, NaOH, KOH, NaCl, CuSO4, etc. Examples are H2CO3, CH3COOH, HOOC-COOH, NH4OH, Ca(OH)2, (NH4)2CO3, Pb(CH3COO)2
 
  • Ions

When a chemical compound in fused state or in aqueous solution breaks up into electrically charged atoms or group of atoms, the charged particles are called ions. A positively charged ion is cation. They migrate towards cathode. A negatively charged ion is an anion. They migrate towards anode.

Differences between cation and anion

Cation Anion
Positively charged Negatively charged
Migrate to cathode Migrate to anode…

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