Problem 80 - Chemistry and Chemical Reactivity

Question

(a) Name and give formulas for two water-soluble compounds containing the \(\mathrm{Cu}^{2+}\) ion. Name two water-insoluble compounds containing the \(\mathrm{Cu}^{2+}\) ion. (b) Name and give formulas for two water-soluble compounds containing the \(\mathrm{Ba}^{2+}\) ion. Name two water-insoluble compounds containing the \(\mathrm{Ba}^{2+}\) ion.

Step-by-Step Solution

Answer

CuSO₄ and CuCl₂ are soluble; Cu(OH)₂ and CuCO₃ are insoluble. Ba(NO₃)₂ and BaCl₂ are soluble; BaSO₄ and BaCO₃ are insoluble.

Step 1: Identify Water-Soluble Compounds with Cu²⁺ Ion

One of the water-soluble compounds containing the \(\mathrm{Cu}^{2+}\) ion is copper(II) sulfate, with the formula \(\mathrm{CuSO_4}\). Another example is copper(II) chloride, with the formula \(\mathrm{CuCl_2}\). These compounds are known to readily dissolve in water.

Step 2: Identify Water-Insoluble Compounds with Cu²⁺ Ion

Copper(II) hydroxide, with the formula \(\mathrm{Cu(OH)_2}\), is a water-insoluble compound containing the \(\mathrm{Cu}^{2+}\) ion. Another example is copper(II) carbonate, \(\mathrm{CuCO_3}\), which is also insoluble in water.

Step 3: Identify Water-Soluble Compounds with Ba²⁺ Ion

One of the water-soluble compounds containing the \(\mathrm{Ba}^{2+}\) ion is barium nitrate, \(\mathrm{Ba(NO_3)_2}\). Another example is barium chloride, \(\mathrm{BaCl_2}\). Both compounds dissolve well in water.

Step 4: Identify Water-Insoluble Compounds with Ba²⁺ Ion

Barium sulfate, \(\mathrm{BaSO_4}\), is a compound containing the \(\mathrm{Ba}^{2+}\) ion that is insoluble in water. Another example of a water-insoluble compound is barium carbonate, \(\mathrm{BaCO_3}\).

Key Concepts

Copper(II) Ion Compounds

Copper(II) ion (Cu²⁺) compounds are chemical substances that contain the copper ion combined with other elements or groups of elements. Copper(II) is in the +2 oxidation state, meaning it has lost two electrons. Two common types of copper(II) compounds are its water-soluble and water-insoluble forms. These compounds find various applications in industries and laboratories due to their chemical properties and reactions.

Barium(II) Ion Compounds

Barium(II) ion (Ba²⁺) compounds are made by combining barium in the +2 oxidation state with other ions or molecules. Barium compounds have unique properties due to the barium ion's large size and high reactivity. They play important roles in fields such as medicine, electronics, and manufacturing. Like copper compounds, they can be classified based on their solubility in water into water-soluble and water-insoluble compounds.

Solubility Rules

Solubility rules are guidelines used to predict whether a compound will dissolve in water. These rules are essential for chemists to understand chemical reactions and design experiments. For instance, compounds containing alkali metal ions and ammonium are generally soluble in water. Solubility also depends on the presence of anions; for example:

• Sulfates are generally soluble, except for those of barium, lead, and calcium.
• Carbonates and hydroxides are generally insoluble, except for those of alkali metals and ammonium.

By applying these rules, one can determine the solubility of various ionic compounds like copper(II) and barium(II) compounds.

Copper Water Soluble Compounds

Some copper(II) compounds are highly soluble in water, making them useful in aqueous solutions. Copper(II) sulfate (\(\mathrm{CuSO_4}\)) is one such compound; it readily dissolves in water to form a blue solution, used in agriculture and chemical testing. Another example is copper(II) chloride (\(\mathrm{CuCl_2}\)), which dissolves well and serves in various chemical syntheses. These soluble compounds allow for easy handling and application in different fields, from electroplating to analytical chemistry.

Barium Water Soluble Compounds

Barium(II) compounds that dissolve in water, like barium nitrate (\(\mathrm{Ba(NO_3)_2}\)) and barium chloride (\(\mathrm{BaCl_2}\)), are significant in various chemical processes. Barium nitrate is of interest in pyrotechnics for its ability to produce green flames, while barium chloride is used in water treatment. These compounds have chemical properties that enable reactions in both laboratory and industrial settings. Their solubility simplifies their use in processes that require the barium ion in a dissolved state.