Problem 63 - A Complete Resource Book in Chemistry for JEE Main

Question

In nitroprusside ion, the iron and NO exist as \(\mathrm{Fe}^{\mathrm{ll}}\) and NO \(^{+}\)rather than \(\mathrm{Fe}^{\mathrm{II}}\) and NO. These forms can be differentiated by (a) estimating the concentration of iron (b) measuring the concentration of \(\mathrm{CN}^{-}\) (c) measuring the solid state magnetic moment (d) thermally decomposing the compound

Step-by-Step Solution

Answer

Use method (c), measuring the solid state magnetic moment, to differentiate the iron and NO forms.

Step 1: Understand the problem

The problem presents a nitrate ion form, which can exist in different oxidation states. You are required to determine which form is correct by using different methods of analysis.

Step 2: Evaluate the methods

Evaluate the methods provided: (a) estimating iron concentration, (b) measuring cyanide ion concentration, (c) using magnetic moment, and (d) thermal decomposition.

Step 3: Consider Iron Oxidation Methods

Measuring the concentration of iron or cyanide would not differentiate between the valence states, as both forms have the same number of each. Therefore, these methods are ineffective.

Step 4: Consider Magnetic Moment Measurement

The magnetic moment can distinguish between different oxidation states. - o oxidation state a p h iron in - 2 d 3 6 o electron c o h e o n f i g o s r a t i o n n, o a t h i s o n o r s t a o m a g n a n t i c a m-i o moment m a t c h e s to o i n t y

Step 5: Consider Thermal Decomposition

This approach does not differentiate between oxidation states directly. Thermal decomposition will primarily address compound stability rather than the electron configuration of iron and NO.

Step 6: Choose the Best Method

The best option for distinguishing between the iron and NO forms is by measuring the solid state magnetic moment, as it can reveal the magnetic properties that are different for h e o and o n f e n a s u +

Step 7: Conclusion

(c) measuring the solid state magnetic moment can differentiate between the different ion forms in a compound.

Key Concepts

Iron Oxidation States

In chemistry, oxidation states refer to the charge of an atom in a molecule or ion. This charge results from the distribution of electrons among the atoms in a chemical compound. Iron is a metal that can exist in multiple oxidation states, with Fe(II) and Fe(III) being the most common. In the case of the nitroprusside ion, iron exists as Fe(II) in combination with the NO⁺ ion.

The oxidation state of iron is crucial because it influences how iron interacts with other molecules and ions. Each state can alter the chemical behavior, such as solubility and reactivity. The identification of iron's oxidation state often requires specific analysis techniques since visual inspection is typically insufficient.

Understanding the oxidation state helps chemists predict and manipulate various reactions in synthesis and industrial applications. In the exercise, determining which oxidation state the iron is in will inform us about the exact nature and behavior of the nitroprusside ion.

Magnetic Moment Measurement

Magnetic moment measurement is an effective tool to determine the oxidation state of a metal in a compound. Each oxidation state has a unique electron configuration that affects its magnetic properties. In transition metals like iron, the arrangement of electrons in d-orbitals plays a crucial role in magnetism.

When you measure the solid state magnetic moment of a compound, you assess the magnetic field produced by the electrons. For iron, if it is in a high-spin state (more unpaired electrons), it will exhibit stronger magnetic properties compared to a low-spin state. This can differentiate between Fe(II) and Fe(III), as typically, Fe(III) has more unpaired electrons than Fe(II).

In the context of the nitroprusside ion, measuring the magnetic moment helps confirm whether iron is in the Fe(II) or Fe(III) condition. This method offers more precision compared to other techniques such as simply measuring concentration, which cannot reveal the electron configuration.

Chemical Analysis Methods

Chemical analysis methods are crucial in identifying the composition and characteristics of a chemical substance. These methods can be categorized into physical techniques and chemical tests. Each approach has its strengths, depending on what is being measured or analyzed.

For the nitroprusside ion, the challenge is in confirming the oxidation state of its components. Methods such as:

• Colorimetric Analysis: Observes the change of color in a solution which may correlate with oxidation states, although it might not provide clear distinction in this scenario.
• Electrochemical Methods: These involve redox reactions and measure changes in electrical properties, giving clues about oxidation levels.
• Spectroscopy: Techniques like UV-Vis or IR can analyze the light absorption of a compound, providing insight into the electron arrangement and hence the oxidation state.

Chemical analysis aims to provide precise measurements and identity for substances, ensuring correct conclusions regarding compounds like the nitroprusside ion.

Coordination Chemistry

Coordination chemistry delves into compounds where a central metal ion is bonded to surrounding ligands. These ligands can be ions or molecules that donate a pair of electrons to the metal, creating a complex.

In the nitroprusside ion, iron acts as the central metal in a coordination complex. It is bonded to ligands such as CN⁻ and NO among others. The properties of these complexes, including their oxidation states, solubility, and reactivity, are heavily influenced by the nature of the metal and ligands involved.

Coordination chemistry is pivotal in the context of the exercise because these interactions define the overall structure and stability of the compound. They also affect how the oxidation state of iron is determined. Through this understanding, one can appreciate how the arrangement of ligands around a metal influences its chemical attributes and how measurements like magnetic moments are connected to these structures.