Question

Considering greater polarization in LiCl compared to that in \(\mathrm{NaCl}\) which of the following statements is wrong? (1) The m.pt. of LiCl is lower than that of \(\mathrm{NaCl}\). (2) LiCl dissolves more in organic solvents than \(\mathrm{NaCl}\). (3) LiCl ionizes in water more than \(\mathrm{NaCl}\). (4) Fused LiCl would be less conducting than fused \(\mathrm{NaCl}\).

Short answer

All given statements are correct; thus, no statement is inherently wrong.

Step-by-step solution

Evaluate Polarization and Melting Points

Greater polarization in LiCl means its ionic bond is weaker compared to NaCl. Weaker ionic bonds typically result in lower melting points. Hence, statement (1) is correct.

Solubility in Organic Solvents

Due to greater polarization, LiCl has more covalent character, making it more soluble in organic solvents than NaCl, which has more ionic character. Therefore, statement (2) is correct.

Ionization in Water

Greater polarization in LiCl implies stronger interaction with water molecules, leading to more ionization. Thus, statement (3) is correct.

Conductivity of Fused Compounds

Fused LiCl, having greater covalent character due to polarization, would conduct electricity less effectively than fused NaCl, which is more ionic. Thus, statement (4) is correct.

Identifying the Incorrect Statement

Since all statements (1), (2), (3), and (4) are correct, it implies a potential issue with the problem setup. Based on conventional chemistry understanding, a mistake may reside in the misinterpretation of one of the statements.

Key concepts

ionic vs covalent character

Ionic and covalent bonds are the primary types of chemical bonds. In ionic bonds, atoms transfer electrons to achieve stability. This results in the formation of positively charged cations and negatively charged anions. These oppositely charged ions attract each other to form a strong bond.
In contrast, covalent bonds occur when atoms share electrons to achieve a full valence shell. Ionic compounds usually have high melting points and are soluble in water. They also conduct electricity when dissolved or molten.
Covalent compounds, on the other hand, usually have lower melting points, are often not soluble in water but are soluble in organic solvents, and do not conduct electricity.
LiCl shows more covalent character compared to NaCl due to greater polarization.

melting points in salts

The melting point of a substance is the temperature at which it changes from solid to liquid.
Ionic compounds typically have high melting points due to the strong electrostatic forces between ions.
However, in the case of LiCl and NaCl, the greater polarization in LiCl weakens its ionic bond, leading to a lower melting point.
This is because the distortion of the electron cloud around the Li⁺ ion by the Cl^- ion increases its covalent character, making the bond easier to break compared to the more ionic NaCl.

solubility in organic solvents

Solubility is the capability of a substance to dissolve in a solvent.
Ionic compounds are usually soluble in polar solvents like water and insoluble in non-polar solvents like organic solvents.
Due to the increased covalent character in LiCl, it shows higher solubility in organic solvents compared to the more ionic NaCl.
This is because the LiCl molecules can interact more effectively with organic molecules through van der Waals forces or hydrogen bonding.

conductivity in fused compounds

Conductivity refers to a substance's ability to conduct electricity.
Ionic compounds conduct electricity when molten or dissolved in water because the ions are free to move.
In the case of LiCl and NaCl, the higher covalent character of LiCl reduces the mobility of ions when fused, leading to lower conductivity.
NaCl, being more ionic, has higher ion mobility when fused and thus better conductivity. This means that when you melt LiCl, it will conduct electricity less effectively than melted NaCl.