Question

In which chemical equation is the number of atoms in the reactants the same as the number of atoms in the products?

CO2+H2O->CH2OH+O2
Li2CO3->LiO+CO2
CH4+O2->CO2+2H2O
Zn+2HCI->H2+ZnCI2

Answer 1

To determine which chemical equation has the same number of atoms in the reactants as in the products, we need to count the number of atoms for each element on both sides of the equation.

1. **CO₂ + H₂O → CH₂OH + O₂**

- Reactants:
- C: 1 (from CO₂)
- O: 3 (2 from CO₂ and 1 from H₂O)
- H: 2 (from H₂O)
- Total: 1 C, 3 O, 2 H (6 atoms)

- Products:
- C: 1 (from CH₂OH)
- O: 3 (1 from CH₂OH and 2 from O₂)
- H: 2 (from CH₂OH)
- Total: 1 C, 3 O, 2 H (6 atoms)

**Total atoms equal: Yes.**

2. **Li₂CO₃ → LiO + CO₂**

- Reactants:
- Li: 2 (from Li₂CO₃)
- C: 1 (from Li₂CO₃)
- O: 3 (3 from Li₂CO₃)
- Total: 2 Li, 1 C, 3 O (6 atoms)

- Products:
- Li: 1 (from LiO)
- O: 1 (from LiO)
- C: 1 (from CO₂)
- O: 2 (from CO₂)
- Total: 1 Li, 1 C, 3 O (5 atoms)

**Total atoms equal: No.**

3. **CH₄ + O₂ → CO₂ + 2H₂O**

- Reactants:
- C: 1 (from CH₄)
- H: 4 (from CH₄)
- O: 2 (from O₂)
- Total: 1 C, 4 H, 2 O (7 atoms)

- Products:
- C: 1 (from CO₂)
- O: 2 (from CO₂)
- H: 4 (from 2H₂O)
- O: 2 (from 2H₂O)
- Total: 1 C, 4 H, 4 O (9 atoms)

**Total atoms equal: No.**

4. **Zn + 2HCl → H₂ + ZnCl₂**

- Reactants:
- Zn: 1 (from Zn)
- H: 2 (from 2HCl)
- Cl: 2 (from 2HCl)
- Total: 1 Zn, 2 H, 2 Cl (5 atoms)

- Products:
- H: 2 (from H₂)
- Zn: 1 (from ZnCl₂)
- Cl: 2 (from ZnCl₂)
- Total: 1 Zn, 2 H, 2 Cl (5 atoms)

**Total atoms equal: Yes.**

The chemical equations where the number of atoms in the reactants is the same as in the products are:

- **CO₂ + H₂O → CH₂OH + O₂**
- **Zn + 2HCl → H₂ + ZnCl₂**

Thus, both of these equations maintain the atom count before and after the reaction.