Question

Let IP stand for ionization potential. The IP, and \(\mathrm{IP}_{2}\) of \(\mathrm{Mg}\) are 178 and \(348 \mathrm{kcal} \mathrm{mol}^{-1}\). The energy required for the following reaction is: \(\mathrm{Mg} \rightarrow \mathrm{Mg}^{2+}+2 \mathrm{e}^{-}\) (a) \(+178\) kcal (b) \(+526 \mathrm{kcal}\) (c) \(-170\) kcal (d) \(-526\) kcal

Short answer

The energy required is +526 kcal; therefore, the correct option is (b).

Step-by-step solution

Understand Ionization Potential

The ionization potential (IP) is the energy required to remove an electron from an atom or molecule. In this problem, the first ionization potential (IP) is the energy required to remove the first electron from a neutral magnesium (Mg) atom to form an Mg⁺ ion, and it is given as 178 kcal/mol.

Calculate Total Ionization Energy

For the equation provided, we need to find the energy required to remove two electrons from Mg, forming Mg²⁺. This requires the sum of the first and second ionization potentials: IP₂ = 348 kcal/mol. We calculate it as follows:\[\text{Total Ionization Energy} = \text{IP}_1 + \text{IP}_2 = 178 \, \text{kcal/mol} + 348 \, \text{kcal/mol} = 526 \, \text{kcal/mol}\]

Determine the Energy Requirement

The total energy required for the reaction \( \mathrm{Mg} \rightarrow \mathrm{Mg}^{2+}+2 \mathrm{e}^{-} \) is the sum of both ionization potentials, calculated to be 526 kcal/mol. As we are removing electrons, the energy required is positive.

Select the Correct Option

Go through the provided options and select the one that matches the calculated total ionization energy. The total energy required is +526 kcal, which corresponds to option (b).

Key concepts

Magnesium Ionization

Magnesium ionization is an interesting process in which magnesium (Mg) loses electrons to become a positively charged ion. In its natural state, magnesium has two electrons in its outer shell. Removing these electrons requires energy. This energy dependency is known as ionization energy.

When magnesium loses one electron, it transforms into the Mg⁺ ion. If it loses another electron, it becomes Mg²⁺. Each removal process takes a specific amount of energy, which is why the concepts of first and second ionization potential (IP) come into play.

Chemistry Problem Solving

Solving chemistry problems involves breaking down complex concepts into simpler steps. Let's take this magnesium ionization example.

First, identify what is known from the problem statement. Here, you are given the ionization potentials:

• IP₁: 178 kcal/mol.
• IP₂: 348 kcal/mol.

Next, understand the reaction:

• The equation is \( \mathrm{Mg} \rightarrow \mathrm{Mg}^{2+}+2 \mathrm{e}^{-} \). We want to determine the energy required to remove two electrons.

By breaking the problem into steps, like understanding terms and performing clear calculations, chemistry problem solving becomes easier and more efficient.

Ionization Energy Calculation

Calculating ionization energy is a crucial part of understanding ionization.
In this example, magnesium requires energy to lose electrons and form different ions. For the ionization of magnesium into Mg²⁺, we calculate total ionization energy by adding the respective energy for removing each electron.

Formula: \[ \text{Total Ionization Energy} = \text{IP}_1 + \text{IP}_2 \]Plug in the values:

• \(178 \, \text{kcal/mol} \)
• \(348 \, \text{kcal/mol} \)

Add these values to find: \[ 526 \, \text{kcal/mol} \]This positive total indicates the energy required to take away both electrons. Understanding this process helps in tackling ionization energy calculations effectively.

NEET Chemistry Preparation

Preparing for NEET chemistry involves mastering various topics, including ionization energy. Understanding these concepts is crucial for scoring well in the competitive exam.

Focus on topics like:

• Ionization Potential
• Periodic Table Trends
• Electron Configuration

When studying ionization, it's important to grasp how energy requirements change with different elements. Practicing problems like magnesium ionization equips you with the skills to tackle complex questions. Use resources like solved exercises and textbooks to deepen your comprehension. Building a strong foundation in these areas enhances your problem-solving abilities for the NEET exam.