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Difficulty: MediumChemical Reactions and Compounds

Complete the statement by providing the correct numerical coefficient and reaction classification for the chemical equation shown.

Answer:In the industrial synthesis of ammonia, the balanced chemical equation is N2+【3】H2→2NH3\text{N}_2 + 【3】\text{H}_2 \rightarrow 2\text{NH}_3, and because multiple reactants combine into one compound, it is classified as a 【synthesis】 reaction.

Answer

The missing coefficient is 3 (or three) and the reaction type is synthesis (or combination).
To balance the equation according to the law of conservation of mass, the 6 hydrogen atoms in 2NH32\text{NH}_3 require a coefficient of 3 for diatomic H2\text{H}_2 (3×2=63 \times 2 = 6). A chemical process where two or more substances combine into a single compound is classified as a synthesis (or combination) reaction.

Step-by-Step Solution

1
Count the total number of nitrogen and hydrogen atoms in the product molecules.
Two ammonia molecules (2NH32\text{NH}_3) contain 2×1=22 \times 1 = 2 nitrogen atoms and 2×3=62 \times 3 = 6 hydrogen atoms.
The law of conservation of mass dictates that the number of atoms of each element on the reactant side must equal the number of atoms on the product side.
2
Determine the coefficient needed for diatomic hydrogen gas (H2\text{H}_2) on the reactant side.
Dividing the required 6 hydrogen atoms by the 2 atoms per H2\text{H}_2 molecule yields a coefficient of 3.
Three molecules of H2\text{H}_2 supply exactly 6 hydrogen atoms (3×2=63 \times 2 = 6), completely balancing the equation.
3
Classify the reaction based on the relationship between reactants and products.
Two distinct elemental reactants (N2\text{N}_2 and H2\text{H}_2) combine chemically to produce a single product compound (NH3\text{NH}_3).
Reactions that follow the general form A+B→ABA + B \rightarrow AB are defined as synthesis or combination reactions.

Key Concept

Balancing chemical equations via conservation of mass and identifying synthesis reactions
Estimated Time:1m 0s
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Topics

Chemical Reactions and Compounds

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