Question

1. choose the best answer.

which of these reactions does not represent a synthesis reaction?
2h₂(g) + o₂(g) → 2h₂o(g)
4al(s) + 3o₂(g) → 2al₂o₃(s)
2kcl(s) → 2k(s) + cl₂(g)
na₂o + co₂ → na₂co₃

1. type the correct numbers in the blanks below. type in 1 if the coefficient is 1.

balance the following synthesis reaction.
n₂ + h₂ → __ nh₃

Explanation:

Question 3

Step1: Recall synthesis reaction definition

A synthesis reaction is \( A + B
ightarrow AB \) (multiple reactants form one product).

Step2: Analyze each reaction

• \( 2H_2(g) + O_2(g)

ightarrow 2H_2O(g) \): 2 reactants → 1 product (synthesis).

• \( 4Al(s) + 3O_2(g)

ightarrow 2Al_2O_3(s) \): 2 reactants → 1 product (synthesis).

• \( 2KCl(s)

ightarrow 2K(s) + Cl_2(g) \): 1 reactant → 2 products (decomposition, not synthesis).

• \( Na_2O + CO_2

ightarrow Na_2CO_3 \): 2 reactants → 1 product (synthesis).

Step1: Balance N atoms

Left: \( N_2 \) (2 N). Right: \( NH_3 \) (1 N per molecule). So need 2 \( NH_3 \) to balance N: \( N_2 + H_2
ightarrow 2NH_3 \).

Step2: Balance H atoms

Right: \( 2NH_3 \) has 6 H. Left: \( H_2 \) (2 H per molecule). So \( H_2 \) coefficient is 3: \( N_2 + 3H_2
ightarrow 2NH_3 \).

Step3: Check N (2 on both) and H (6 on both).

Answer:

\( 2KCl(s)
ightarrow 2K(s) + Cl_2(g) \) (the third option)

Question 4