Question

\(\mathrm{K} 1\) and \(\mathrm{CuSO}_{4}\) solution when mixed gives (a) \(\mathrm{K}_{2} \mathrm{SO}_{4}+\mathrm{Cu}_{2} \mathrm{I}_{2}+\mathrm{I}_{2}\) (b) \(\mathrm{Cu}_{2} \mathrm{I}_{2}+\mathrm{K}_{2} \mathrm{SO}_{4}\) (c) \(\mathrm{CuI}_{2}+\mathrm{K}_{2} \mathrm{SO}_{4}\) (d) \(\mathrm{K}_{2} \mathrm{SO}_{4}+\mathrm{CuI}_{2}+\mathrm{I}_{2}\)

Short answer

The correct answer is (a) K₂SO₄ + Cu₂I₂ + I₂.

Step-by-step solution

Identify the Reactants

The reactants given in the exercise are K (potassium) and CuSO₄ (copper(II) sulfate). These will be mixed to find the products.

Determine the Possible Products

When K and CuSO₄ react, they can potentially form K₂SO₄ (potassium sulfate) and copper iodide compounds as part of the double displacement reaction. To get all possible combinations, the complete reaction should also consider the formation of CuI₂ (copper(II) iodide) or Cu₂I₂ (copper(I) iodide) and iodine (I₂).

Balance the Reaction

Consider the double displacement reaction: 1. Replace the sulfate ion with K to form K₂SO₄. 2. The remaining compound could result in Cu₂I₂ along with I₂ (since I can also combine to form I₂ molecules as a result of change in oxidation state from Cu²⁺ to Cu⁺).

Evaluate the Options

The correct answer includes both iodide and iodine molecules as well as potassium sulfate. The compound with copper might exist in the form Cu₂I₂ (copper(I) iodide) due to possible disproportionation of Cu(I) to Cu(II) and Cu. Among the choices, option (a) includes Cu₂I₂, K₂SO₄, and I₂.

Key concepts

Copper(I) Iodide

Copper(I) Iodide is a compound where copper exists in the +1 oxidation state. It is often represented as Cu₂I₂. Copper has two main oxidation states: +1 and +2. In Cu₂I₂, each copper atom shares iodine with another copper atom, resulting in a dual copper presence. This structure differs from copper(II) iodide, where copper exists in the +2 state. Understanding the differences in oxidation states is crucial, as it affects the stability and predictability of reactions.
In chemical reactions like the one in the exercise, the formation of Cu₂I₂ is based on copper’s ability to disproportionate. Disproportionation occurs when an element in one oxidation state is simultaneously oxidized and reduced to form two different compounds.

• Cu⁺ is oxidized to Cu²⁺ and reduced to neutral Cu.
• This reaction stabilization favors the creation of Cu₂I₂.

Recognizing these patterns helps predict possible products in reactions such as double displacement reactions.
Double displacement reactions typically involve the exchange of ions between reactants to form new products, making this information central to determining the final product configuration.

Potassium Sulfate

Potassium sulfate, or K₂SO₄, is a common inorganic chemical compound used extensively as a fertilizer. Potassium sulfate is formed when potassium ions ( K⁺) exchange places with other metal ions in salts during a reaction, as seen in double displacement reactions.
This compound is stable and forms when potassium reacts with sulfate ions ( SO₄²⁻). In the context of a chemical equation, potassium sulfate is often the predictable outcome of a reaction involving potassium.
The formation of K₂SO₄ shows how ionic compounds can easily swap cations, making balancing the chemical equation straightforward. In the textbook solution, observing K₂SO₄ as a product reflects the movement of ions that is standard in reactions involving sulfates.

• The potassium ion bonds with sulfate to create K₂SO₄.
• Stability of K₂SO₄ is high, favoring its consistent appearance in these reactions.

This knowledge of potassium's affinity for pairing with sulfate ions is crucial when balancing and predicting outcomes of chemical reactions.

Balancing Chemical Equations

Balancing chemical equations is critical to accurately describe chemical reactions. It requires ensuring the number of atoms of each element is the same on both sides of the equation. The law of conservation of mass directs this balancing act, confirming that matter is neither created nor destroyed in chemical reactions.
In a balanced equation, reactants are transformed into products without the creation of additional ions or molecules that were not originally present. The textbook exercise shows an example where potassium and copper sulfate react to form new compounds, needing precise balance to reflect reality.

• Identify each reactant and product involved.
• Use coefficients to balance each element across the equation.

For instance, if Cu₂I₂ and I₂ are products, coefficients need adjusting to balance iodine on both sides. This process ensures the theory aligns with experimental results, showcasing the precision needed in chemistry.
Ultimately, mastering balancing techniques strengthens understanding of chemical reaction dynamics, providing a strong foundation for more complex chemistry concepts.