Problem 53 - A Complete Resource Book in Chemistry for JEE Main

Question

What happens when \(\mathrm{CCl}_{4}\) is treated with \(\mathrm{AgNO}_{3}\) solution? (a) a white precipitate of \(\mathrm{AgCl}\) will be formed (b) \(\mathrm{NO}_{2}\) will be evolved (c) \(\mathrm{CCl}_{4}\) will dissolve in \(\mathrm{AgNO}_{3}\) solution (d) nothing will happen

Step-by-Step Solution

Answer

(d) nothing will happen

Step 1: Identify Components

Let's identify the substances involved in the reaction: Carbon tetrachloride, \(\mathrm{CCl}_4\), and silver nitrate, \(\mathrm{AgNO}_3\). \(\mathrm{CCl}_4\) is a covalent compound, while \(\mathrm{AgNO}_3\) is an ionic compound.

Step 2: Consider Possible Reactions

\(\mathrm{CCl}_4\) is a non-polar molecule and does not ionize in solution, which means it cannot provide \(\mathrm{Cl}^-\) ions. Therefore, it will not react with the \(\mathrm{Ag}^+\) ions in solution to form \(\mathrm{AgCl}\) which would result in a white precipitate. Without available chloride ions, no \(\mathrm{AgCl}\) can form.

Step 3: Evaluate Solubility

\(\mathrm{CCl}_4\) is insoluble in water and typically will not react with \(\mathrm{AgNO}_3\) in aqueous solution. This implies there will be no dissolution or visible chemical reaction between the two substances.

Step 4: Conclusion

Since \(\mathrm{CCl}_4\) does not provide \(\mathrm{Cl}^-\) ions to react with \(\mathrm{Ag}^+\) ions and does not dissolve in \(\mathrm{AgNO}_3\) solution, no reaction or observable change occurs when \(\mathrm{CCl}_4\) is mixed with \(\mathrm{AgNO}_3\).

Key Concepts

Covalent Compounds

Covalent compounds are chemical compounds where atoms are connected by covalent bonds. They share pairs of electrons between atoms. This sharing helps each atom achieve a full outer shell, resembling the electron configuration of noble gases. A well-known characteristic of covalent compounds is their existence in forms that range from gases to liquids or even solids, seen in substances like water (H₂O) or carbon tetrachloride (CCl₄).

• Covalent bonds occur between non-metal atoms.
• The bonds involve the sharing of electron pairs.
• Covalent compounds can be polar or non-polar, depending on the distribution of electrons.

A particularly important aspect is considering whether a compound is polar or non-polar. For instance, CCl₄ is non-polar due to its symmetrical structure, which leads to an even distribution of charge. This impacts its solubility and reactivity in various solvents and conditions.

Ionic Compounds

Ionic compounds are formed when there is a transfer of electrons from one atom to another, leading to the creation of ions. These are typically formed between metals and non-metals, where metals lose electrons to become cations, and non-metals gain electrons to become anions. A classic example is sodium chloride (NaCl), formed when sodium gives up an electron to chlorine.

• Ions are charged particles due to loss or gain of electrons.
• Ionic bonds result from electrostatic attraction between oppositely charged ions.
• These compounds generally form crystalline solids with high melting and boiling points.

Silver nitrate (AgNO₃) is an ionic compound worth noting. Its solubility in water, a polar solvent, allows it to dissociate into Ag⁺ and NO₃⁻ ions, which becomes significant in precipitation reactions when the right ions are present.

Solubility

Solubility refers to the ability of a substance to dissolve in a solvent to form a homogeneous mixture or solution. The degree of solubility varies greatly between substances and depends on the nature of both the solute and solvent.

• Polar solutes tend to dissolve in polar solvents.
• Non-polar solutes generally dissolve better in non-polar solvents.
• Temperature and pressure can affect solubility.

CCl₄, as a non-polar molecule, is not soluble in polar solvents like water or aqueous solutions such as silver nitrate. This insolubility implies no reaction would occur when CCl₄ is mixed with AgNO₃, aligning with the observed lack of reaction.

Precipitation Reactions

Precipitation reactions occur when two soluble ionic compounds in solution react to form an insoluble solid, known as a precipitate. This happens when the ionization of compounds results in a product with low solubility in the solvent used.

• Involves double displacement reactions.
• Occurs when a product formed is insoluble in the solution.
• Commonly observed as the formation of a solid from a liquid mixture.

The classic example is the reaction between AgNO₃ and Cl⁻ ions, resulting in the formation of a white AgCl precipitate. However, since CCl₄ is a covalent compound and does not dissolve to provide free Cl⁻ ions, no precipitate forms when it is treated with AgNO₃.