Problem 37 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following is not correctly matched. List I \(\quad\) List II (a) \(\mathrm{Cu}_{2} \mathrm{O}\) Red (b) \(\mathrm{Cu}_{2} \mathrm{I}_{2}\) Blue (c) \(\mathrm{Fe}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]_{3}\) Blue (d) \(\mathrm{CuO}\) Black

Step-by-Step Solution

Answer

Option (b) \( \mathrm{Cu}_{2} \mathrm{I}_{2} \) is incorrectly matched; it is white, not blue.

Step 1: Analyze Each Option in List I and List II

We are given a set of compounds in List I and their corresponding colors in List II. We need to determine which pair in the lists is incorrectly matched. Let's review each compound's color:(a) \( \mathrm{Cu}_{2} \mathrm{O} \) is known to be red.(b) \( \mathrm{Cu}_{2} \mathrm{I}_{2} \) is actually white, not blue.(c) \( \mathrm{Fe}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]_{3} \) is known as Prussian blue, which is blue in color.(d) \( \mathrm{CuO} \) has a black color.Therefore, by understanding the actual colors of these compounds, we need to identify which one is not correctly matched.

Step 2: Identify the Incorrectly Matched Pair

From the analysis in Step 1, we see the following:- Option (a) \( \mathrm{Cu}_{2} \mathrm{O} \) matches correctly with Red.- Option (b) \( \mathrm{Cu}_{2} \mathrm{I}_{2} \) is listed as Blue, but it should be White.- Option (c) \( \mathrm{Fe}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]_{3} \) correctly matched as Blue.- Option (d) \( \mathrm{CuO} \) correctly matched as Black.Thus, option (b) \( \mathrm{Cu}_{2} \mathrm{I}_{2} \) is incorrectly matched with Blue instead of its actual color, White.

Key Concepts

Cu2O red

Copper(I) oxide, represented as \( \text{Cu}_2\text{O} \), is notable for its distinct red color. This compound is a reddish solid and one of the more stable copper oxides.

Given its appealing hue, \( \text{Cu}_2\text{O} \) has been used historically in ceramics and glass to create red colors. This thriving industry appreciates its vividness and stability.

Understanding the properties of \( \text{Cu}_2\text{O} \) helps us recognize the importance of identifying compounds by color, which plays a critical role in applications ranging from art to chemistry.

Cu2I2 white

Copper(I) iodide, denoted as \( \text{Cu}_2\text{I}_2 \), exhibits a white color. Contrary to what some might expect, this compound does not exhibit vivid colors like many other copper compounds.

The white color of \( \text{Cu}_2\text{I}_2 \) can be attributed to its specific molecular structure. In terms of practical use, this white compound is used in organic synthesis and radiation or thermal conductors due to its stability.

Identifying \( \text{Cu}_2\text{I}_2 \) correctly depends on knowing not only its structural formula but also its color attributes. This understanding helps us avoid common pitfalls in chemical identification and matching of compounds.

Prussian blue

Prussian blue is the common name for \( \text{Fe}_4\left[\text{Fe}(\text{CN})_6\right]_3 \), which is renowned for its intense blue color. This iconic compound has a rich history and significance in art and medicine.

First synthesized as a dye for paints and inks, Prussian blue's vibrant hue makes it a continuous favorite in artistic fields. Moreover, it plays a crucial role in medical applications as a treatment for certain types of heavy metal poisoning.

Its bright blue color is a result of charge transfer between iron ions within its crystalline structure. Knowing Prussian blue's composition and applications enhances our comprehension of its utility and fascination.

CuO black

Copper(II) oxide, represented by \( \text{CuO} \), is well-known for its deep black color. It is one of the common forms of copper oxides and is utilized in diverse industrial applications.

The black pigment of \( \text{CuO} \) is utilized for tinting and staining glass or ceramics, adding aesthetic and functional properties. Additionally, it plays a role in catalysis processes, electronic materials, and even as a component in batteries.

Recognizing \( \text{CuO} \) and understanding why it appears black provides valuable insight into its properties and potential industrial applications. Knowledge of such basic properties aids in various scientific and practical pursuits.