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 of each element on both sides of the equations.
A. CO2 + H2O -- CH2OH + O2
Reactants:
- C: 1 (from CO2)
- O: 3 (2 from CO2 + 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 + 2 from O2)
- H: 2 (from CH2OH)
Total = 1 C + 3 O + 2 H = 6 atoms
The total number of atoms is the same in the reactants and products.
B. 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)
- H: 4 (from 2H2O)
- O: 3 (2 from H2O + 1 from CO2)
Total = 1 C + 4 H + 3 O = 8 atoms
The total number of atoms is not the same.
C. Zn + 2HCl -- H2 + ZnCl2
Reactants:
- Zn: 1
- 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 = 2 H + 1 Zn + 2 Cl = 5 atoms
The total number of atoms is the same.
D. Li2CO3 -- LiO + CO2
Reactants:
- Li: 2 (from Li2CO3)
- C: 1 (from Li2CO3)
- O: 3 (from Li2CO3)
Total = 2 Li + 1 C + 3 O = 6 atoms
Products:
- Li: 1 (from LiO)
- C: 1 (from CO2)
- O: 3 (2 from CO2 + 1 from LiO)
Total = 1 Li + 1 C + 3 O = 5 atoms
The total number of atoms is not the same.
After evaluating all options, A (CO2 + H2O -- CH2OH + O2) and C (Zn + 2HCl -- H2 + ZnCl2) have the same number of atoms in the reactants and products.
Thus, the correct answer is:
A. CO2 + H2O -- CH2OH + O2 and C. Zn + 2HCl -- H2 + ZnCl2