Question

rocket engines can be fueled by liquid hydrogen. the liquid hydrogen reacts with liquid oxygen, producing water vapor and releasing an enormous amount of energy.

consider the following reaction:

4 molecules of hydrogen (h₂) react with 2 molecules of oxygen (o₂) to produce some amount of water (h₂o).

complete the table below.

chemical element	number of atoms in the reaction
o

during this reaction, how many molecules of water (h₂o) are produced?

Explanation:

Part 1: Number of H atoms

Step1: Calculate H atoms from \( H_2 \)

Each \( H_2 \) molecule has 2 H atoms. There are 4 \( H_2 \) molecules. So total H atoms: \( 4 \times 2 = 8 \).

Step2: Verify (no change, conservation of mass)

In a chemical reaction, the number of atoms is conserved. So H atoms in products (water) will equal those in reactants. So H atoms: 8.

Part 2: Number of O atoms

Step1: Calculate O atoms from \( O_2 \)

Each \( O_2 \) molecule has 2 O atoms. There are 2 \( O_2 \) molecules. So total O atoms: \( 2 \times 2 = 4 \).

Step2: Verify (conservation of mass)

O atoms in products equal those in reactants. So O atoms: 4.

Part 3: Molecules of \( H_2O \) produced

Step1: Use H atoms to find \( H_2O \)

Each \( H_2O \) has 2 H atoms. Total H atoms: 8. So \( H_2O \) molecules from H: \( \frac{8}{2} = 4 \).

Step2: Verify with O atoms

Each \( H_2O \) has 1 O atom. Total O atoms: 4. So \( H_2O \) molecules from O: \( \frac{4}{1} = 4 \). Consistent.

Answer:

s:

• Number of H atoms: \( \boldsymbol{8} \)
• Number of O atoms: \( \boldsymbol{4} \)
• Molecules of \( H_2O \): \( \boldsymbol{4} \)