Question

One mole of magnesium nitride on the reaction with an excess of water gives: (a) Two moles of ammonia (b) Two moles of nitric acid (c) One mole of ammonia (d) One mole of nitric acid

Short answer

(a) Two moles of ammonia

Step-by-step solution

Identify Reactants and Products

Start by identifying the chemical reaction involved. The reaction of magnesium nitride with water produces magnesium hydroxide and ammonia. The relevant chemical equation is: \[ \text{Mg}_3\text{N}_2 + 6\text{H}_2\text{O} \rightarrow 3\text{Mg(OH)}_2 + 2\text{NH}_3 \]

Analyze the Balanced Chemical Equation

From the balanced equation, observe that 1 mole of magnesium nitride (\( \text{Mg}_3\text{N}_2 \)) reacts with 6 moles of water to yield 3 moles of magnesium hydroxide and 2 moles of ammonia (\( \text{NH}_3 \)).

Determine the Product Formed

The question asks for the amount of ammonia produced. The balanced equation shows that 1 mole of magnesium nitride produces 2 moles of ammonia when reacted with water.

Key concepts

Balanced Chemical Equations

When we talk about balanced chemical equations, we are really talking about ensuring that the number of atoms for each element is equal on both sides of the equation.
This is crucial for understanding chemical reactions because it reflects the conservation of mass.
In our exercise, the equation \[ \text{Mg}_3\text{N}_2 + 6\text{H}_2\text{O} \rightarrow 3\text{Mg(OH)}_2 + 2\text{NH}_3 \] is balanced because it has the same number of each type of atom on both sides of the arrow, which represents the direction of the reaction.

• For magnesium, there are 3 atoms on the left and 3 atoms on the right.
• Nitrogen, similarly, is balanced with 2 atoms on the left and 2 on the right (inside the ammonia molecules).
• Hydrogen and oxygen are also balanced when you calculate all molecules on both sides.

This equation shows us exactly how reactants are transformed into products.
Balancing chemical equations helps us predict how much product will be produced from given reactants, ensuring accuracy in scientific calculations.

Moles in Chemistry

The concept of moles is fundamental in chemistry as it allows us to count particles by weighing them.
One mole is a specific number of particles, precisely Avogadro's number, which is approximately \(6.022 \times 10^{23}\).
This is similar to how a dozen means 12, regardless of whether you're talking about eggs or cookies.

• In our reaction, one mole of magnesium nitride (\(\text{Mg}_3\text{N}_2\)) reacts with six moles of water.
• This results in three moles of magnesium hydroxide and two moles of ammonia.

Understanding moles helps us to interpret chemical equations in practical terms—how much of each substance participates in, and is produced by, the reaction.
Simply put, it's about unifying particles and weights to give meaning to chemical reactions.This makes moles incredibly useful not only for theoretical chemistry but also for laboratory work, where quantities of substances must be precisely measured and balanced.

Reaction Products

In chemical reactions, understanding the formation of products is just as important as determining the reactants involved.
For the given exercise, the reaction between magnesium nitride and water produces two main products: magnesium hydroxide and ammonia (NH₃).

• Magnesium hydroxide forms as a solid, which is often seen as a precipitate in many reactions.
• Ammonia is known for its distinct, pungent smell and is released as a gas in this reaction.

The balanced equation, therefore, tells us not only what products will be formed but in what quantities they will appear relative to the reactants.
Understanding this allows us to predict product yields and makes it possible to scale up reactions from lab tests to industrial processes.
When you know the products, you can also better understand the conditions required for the reaction and any subsequent steps needed to handle or utilize those products.
Thus, learning to interpret reaction products helps ensure you can predict the outcomes of chemical reactions with accuracy.