To determine which chemical equation has the same number of atoms in the reactants as in the products, we need to count the atoms on both sides of each equation.
-
Zn + 2HCl → H2 + ZnCl2
- Reactants:
- Zn: 1
- H: 2 (from 2HCl)
- Cl: 2 (from 2HCl)
- Total: 1 + 2 + 2 = 5 atoms
- Products:
- H: 2 (from H2)
- Zn: 1 (from ZnCl2)
- Cl: 2 (from ZnCl2)
- Total: 2 + 1 + 2 = 5 atoms
- Total atoms = 5 on both sides, so it's balanced.
- Reactants:
-
CH4 + O2 → CO2 + 2H2O
- Reactants:
- C: 1 (from CH4)
- H: 4 (from CH4)
- O: 2 (from O2)
- Total: 1 + 4 + 2 = 7 atoms
- Products:
- C: 1 (from CO2)
- H: 4 (from 2H2O)
- O: 3 (2 from CO2 and 1 from 2H2O)
- Total: 1 + 4 + 3 = 8 atoms
- Total atoms ≠ 7 on reactants and 8 on products.
- Reactants:
-
Li2CO3 → LiO + CO2
- Reactants:
- Li: 2 (from Li2CO3)
- C: 1 (from Li2CO3)
- O: 3 (from Li2CO3)
- Total: 2 + 1 + 3 = 6 atoms
- Products:
- Li: 1 (from LiO)
- O: 2 (1 from LiO and 2 from CO2)
- C: 1 (from CO2)
- Total: 1 + 2 + 1 = 4 atoms
- Total atoms ≠ 6 on reactants and 4 on products.
- Reactants:
-
CO2 + H2O → CH2OH + O2
- Reactants:
- C: 1 (from CO2)
- O: 3 (2 from CO2 and 1 from H2O)
- H: 2 (from H2O)
- Total: 1 + 3 + 2 = 6 atoms
- Products:
- C: 1 (from CH2OH)
- O: 3 (from CH2OH and O2, 2 from O2 and 1 from CH2OH)
- H: 2 (from CH2OH)
- Total: 1 + 3 + 2 = 6 atoms
- Total atoms = 6 on both sides, so it's balanced.
- Reactants:
Based on the balance assessment:
- Correct answer: Zn + 2HCl → H2 + ZnCl2 and CO2 + H2O → CH2OH + O2 both have the same number of atoms in reactants and products. However, given the context of the question, you typically enter only one balanced equation. So, you can choose either, but the first one listed or simply say they are both valid in the responses expected.
Thus, Zn + 2HCl → H2 + ZnCl2 can be considered an appropriate answer if you are to choose one.