Problem 71 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following compound is known as white vitriol? (a) \(\mathrm{ZnSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}\) (b) \(\mathrm{Na}_{2} \mathrm{SO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}\) (c) \(\mathrm{CaCO}_{4} \cdot 2 \mathrm{H}_{2} \mathrm{O}\) (d) \(\mathrm{MgSO}_{4}^{4} .7 \mathrm{H}_{2} \mathrm{O}\)

Step-by-Step Solution

Answer

The compound \(\mathrm{ZnSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}\) is known as white vitriol.

Step 1: Identify Compounds

Review the chemical names of each compound to understand their composition: (a) \(\mathrm{ZnSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}\) is Zinc Sulfate Heptahydrate, (b) \(\mathrm{Na}_{2} \mathrm{SO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}\) is Sodium Sulfate Hydrate (incorrectly written, possibly intended as heptahydrate), (c) \(\mathrm{CaCO}_{4} \cdot 2 \mathrm{H}_{2} \mathrm{O}\) has an incorrect formula (no such common compound, likely a mistake), (d) \(\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}\) is Magnesium Sulfate, commonly known as Epsom salt.

Step 2: Recall Common Names

Use your knowledge of chemical common names: - \(\mathrm{ZnSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}\) is known as white vitriol. - \(\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}\) is known as Epsom salt. Other given compounds do not correspond to common names widely used.

Key Concepts

White Vitriol

White vitriol is the historical name given to a chemical compound widely known as zinc sulfate heptahydrate (\(\mathrm{ZnSO}_4 \cdot 7 \mathrm{H}_2\mathrm{O}\)). This name comes from its crystalline appearance and historical applications in various industries. White vitriol finds use in horticulture, medicine, and as a precursor in chemical production.
Its historical significance lies in its common usage as an emetic and astringent. Over time, it became part of the extensive list of compounds named using historical nomenclature.

Zinc Sulfate Heptahydrate

Zinc sulfate heptahydrate is represented by the chemical formula \(\mathrm{ZnSO}_4 \cdot 7 \mathrm{H}_2\mathrm{O}\), indicating that each molecule is composed of zinc, sulfur, and water of crystallization. This compound consists of seven water molecules (heptahydrate) bound to zinc sulfate. Understanding its composition is important for applications:

• Used as a dietary supplement, it can help treat zinc deficiency.
• In agriculture, it serves as a soil additive to correct zinc-depleted soils.
• It also plays a role in certain industrial processes, including the production of rayon and as a mordant in dyeing.

The heptahydrate form is different from other hydrates, such as monohydrate, due to its higher water content, affecting solubility and stability.

Common Names of Compounds

Chemical nomenclature can be complex, especially when common names are considered. These terms are often derived from historical uses, physical appearance, or the compound's origin. Some common practices in naming include:

• A compound may have several common names alongside its systematic name, used in different industries or over time.
• The names often give clues about the compound's properties, for example, Epsom salt for magnesium sulfate due to its use as bath salts.
• Emphasis is placed on learning both systematic and common names to understand chemical literature and applications fully.

Being familiar with common names enables one to recognize substances beyond their formula, making scientific communication more efficient.