Question

lons of \(\mathrm{Ca}\), Ba and Sr precipitate in \(\mathrm{V}\) group as their (a) sulphides (b) sulphates (c) oxides (d) carbonates

Short answer

Ions of Ca, Ba, and Sr precipitate as sulphates in the V group.

Step-by-step solution

Understanding the Exercise

We need to determine in which form (sulphides, sulphates, oxides, or carbonates) the ions of calcium (\(\mathrm{Ca}^{2+}\)), barium (\(\mathrm{Ba}^{2+}\)), and strontium (\(\mathrm{Sr}^{2+}\)) precipitate in the V group. This involves understanding which of these compounds is commonly insoluble in water and known to precipitate.

Review Solubility Rules

According to solubility rules, most sulphates are soluble in water; however, notable exceptions include sulphates of barium, strontium, and calcium, which are insoluble and precipitate out of solution.

Identifying Precipitating Compounds

Given the solubility rules, it is clear that the sulphates of \(\mathrm{Ca}^{2+}\), \(\mathrm{Ba}^{2+}\), and \(\mathrm{Sr}^{2+}\) form insoluble compounds and precipitate, classifying them under the V group cations.

Conclusion

Therefore, the ions of calcium, barium, and strontium precipitate in the V group specifically as their sulphates due to the insolubility of \(\mathrm{CaSO_4}\), \(\mathrm{BaSO_4}\), and \(\mathrm{SrSO_4}\) in water.

Key concepts

Precipitation

Precipitation is a process in chemistry where a solid substance forms in a liquid solution. This happens when the concentration of ions in the solution exceeds their solubility limit, resulting in the formation of a solid, called a precipitate. Different chemical reactions can lead to precipitation.
One common scenario involves mixing solutions of two ionic compounds, leading to the formation of an insoluble product. For example, if solutions containing barium ions (\(\mathrm{Ba}^{2+}\)) and sulfate ions (\(\mathrm{SO}_4^{2-}\)) are mixed, barium sulfate (\(\mathrm{BaSO}_4\)) will precipitate out. This is because barium sulfate has low solubility in water.

• Precipitation reactions help in identifying ions, especially in qualitative analysis.
• This process is utilized to separate different substances in a mixture.

Overall, recognizing the conditions under which precipitation occurs is essential in predicting and explaining various chemical processes.

Alkaline Earth Metals

The alkaline earth metals are a group of elements in the second column of the periodic table, including magnesium, calcium, strontium, barium, and radium. Calcium (\(\mathrm{Ca}\)), strontium (\(\mathrm{Sr}\)), and barium (\(\mathrm{Ba}\)) are often involved in precipitation reactions because of their tendency to form insoluble compounds with certain anions, such as sulfate.
The properties of these metals include being shiny, silvery-white, and relatively soft. They have two valence electrons, making them quite reactive, although less so than the alkali metals. Here's why they are significant:

• They form compounds that frequently engage in precipitation reactions due to low solubility totals.
• Their reactivity is utilized to prepare various industrial compounds.
• They play important roles in biological systems, such as calcium in bone structures.

These metals are integral to many chemical processes and practical applications.

Insoluble Sulphates

Insoluble sulphates are specific sulfate compounds that do not dissolve well in water, leading to their precipitation when formed. According to solubility rules, most sulfate salts are soluble, yet the sulfates of calcium (\(\mathrm{CaSO_4}\)), strontium (\(\mathrm{SrSO_4}\)), and barium (\(\mathrm{BaSO_4}\)) are exceptions.
These sulphates stand out because they appear as precipitates in many chemical reactions, especially in analytical chemistry for detecting and separating different ions:

• \(\mathrm{CaSO_4}\): Used in construction as gypsum and plaster of Paris.
• \(\mathrm{SrSO_4}\): Known as celestite and has minor uses in pyrotechnics.
• \(\mathrm{BaSO_4}\): Utilized in medical imaging due to its opacity to X-rays.

In practical applications, understanding which sulphates are insoluble helps in fields ranging from construction to medicine.

V Group Cations

V group cations refer to a category of ions in a specific analytical group classification. This group commonly includes cations such as calcium (\(\mathrm{Ca}^{2+}\)), barium (\(\mathrm{Ba}^{2+}\)), and strontium (\(\mathrm{Sr}^{2+}\)) based on their chemical behavior and solubility profiles.
The significance of classifying these ions in the V group comes from:

• They precipitate as insoluble sulphates, serving as a clear identifier for this group's cations.
• Their behavior is key in qualitative analysis when identifying ions in solutions.
• This classification aids in systematically determining the presence of these ions through specific chemical reactions.

Ultimately, V group cations play a crucial role in analytical chemistry as they allow scientists to easily separate and identify specific ions based on their tendency to form insoluble compounds.