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

Write the Chemical Reaction

First, write the balanced chemical equation for the reaction of magnesium nitride (\( \text{Mg}_3\text{N}_2 \)) with water. The chemical reaction can be expressed as follows: \[ \text{Mg}_3\text{N}_2 + 6\text{H}_2\text{O} \rightarrow 3\text{Mg}(\text{OH})_2 + 2\text{NH}_3 \] This shows that one mole of magnesium nitride reacts with six moles of water to produce three moles of magnesium hydroxide and two moles of ammonia.

Analyze the Products

From the balanced chemical equation, observe the products formed. It is evident from the equation that ammonia (\(\text{NH}_3\)) is one of the products and the number of moles is two per mole of magnesium nitride.

Determine the Correct Answer

Based on the reaction, identify which option matches the number of moles of ammonia produced. The equation indicates that two moles of ammonia are produced from one mole of magnesium nitride. Therefore, the correct answer is (a) Two moles of ammonia.

Key concepts

Stoichiometry

Stoichiometry is the quantitative relationship between reactants and products in a chemical reaction. It is essential in chemistry to help predict how much product will form from given amounts of reactants. To understand stoichiometry, consider the balanced chemical equation from the original exercise: \[ \text{Mg}_3\text{N}_2 + 6\text{H}_2\text{O} \rightarrow 3\text{Mg}(\text{OH})_2 + 2\text{NH}_3 \] This equation shows precise amounts of each substance participating in the reaction:

• 1 mole of \( \text{Mg}_3\text{N}_2 \)
• Reacting with 6 moles of \( \text{H}_2\text{O} \)
• Produces 3 moles of \( \text{Mg}(\text{OH})_2 \)
• And 2 moles of \( \text{NH}_3 \)

The coefficients in the balanced equation indicate the ratio of moles of reactants to products, which is crucial for calculations in stoichiometry. When you know the amount of one reactant, you can use these coefficients to calculate the amount of other reactants needed or the products formed. Stoichiometry ensures precision in chemical manufacturing and laboratory experiments to maximize yield and efficiency.

Chemical Equations

Chemical equations are symbolic representations of chemical reactions. They illustrate how reactants transform into products, using chemical formulas and coefficients. Writing a correct chemical equation involves balancing it so that the number of atoms of each element is the same on both sides of the equation.Consider the chemical reaction:\[ \text{Mg}_3\text{N}_2 + 6\text{H}_2\text{O} \rightarrow 3\text{Mg}(\text{OH})_2 + 2\text{NH}_3 \]In this balanced equation:

• The reactants (\( \text{Mg}_3\text{N}_2 \) and \( \text{H}_2\text{O} \)) appear on the left side.
• The products (\( \text{Mg}(\text{OH})_2 \) and \( \text{NH}_3 \)) are found on the right side.
• Subscripts denote the number of atoms in a molecule.
• Coefficients before each chemical formula tell us the number of moles involved.

Balanced equations are fundamental because they obey the law of conservation of mass. This law states that matter is neither created nor destroyed in a chemical reaction. Thus, the mass of reactants must equal the mass of products.

Reaction Products

Understanding reaction products is crucial when exploring chemical reactions, as they are the substances formed from reactants. The reaction of magnesium nitride with water, for instance, yields ammonia and magnesium hydroxide:\[ \text{Mg}_3\text{N}_2 + 6\text{H}_2\text{O} \rightarrow 3\text{Mg}(\text{OH})_2 + 2\text{NH}_3 \]Here, reaction products include:

• Magnesium hydroxide (\( \text{Mg}(\text{OH})_2 \)), a white solid used in antacids and laxatives.
• Ammonia (\( \text{NH}_3 \)), a colorless gas with a pungent smell, used widely as a fertilizer.

Identifying products is essential because it helps understand the purpose and utilization of the chemical reaction. For example, producing ammonia is vital for agriculture, and it is crucial to recognize these outcomes when designing and executing chemical synthesis. Reaction products can also provide insight into the feasibility and efficiency of the reaction.