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 each type of atom in both sides of the equation.
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Li2CO3 → LiO + CO2
- Reactants: 2 Li, 1 C, 3 O (total = 2 + 1 + 3 = 6 atoms)
- Products: 1 Li, 1 O, 1 C, 2 O (total = 1 + 1 + 1 + 2 = 5 atoms)
- Not balanced.
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CO2 + H2O → CH2OH + O2
- Reactants: 1 C, 2 O (from CO2) + 2 H, 1 O (from H2O) = 1 C, 4 O, 2 H (total = 1 + 4 + 2 = 7 atoms)
- Products: 1 C, 2 H, 1 O (from CH2OH) + 2 O = 1 C, 2 H, 3 O (total = 1 + 2 + 3 = 6 atoms)
- Not balanced.
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Zn + 2HCl → H2 + ZnCl2
- Reactants: 1 Zn, 2 H, 2 Cl (total = 1 + 2 + 2 = 5 atoms)
- Products: 1 H, 2 Cl (from ZnCl2) + 2 H = 1 Zn, 2 Cl, 2 H (total = 1 + 2 + 2 = 5 atoms)
- Balanced.
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CH4 + O2 → CO2 + 2H2O
- Reactants: 1 C, 4 H, 2 O (total = 1 + 4 + 2 = 7 atoms)
- Products: 1 C, 2 O (from CO2) + 4 H (from 2 H2O) = 1 C, 4 H, 2 O (total = 1 + 4 + 2 = 7 atoms)
- Balanced.
The equation where the number of atoms in the reactants is the same as the number of atoms in the products is:
Zn + 2HCl → H2 + ZnCl2
This is one correct example, while CH4 + O2 → CO2 + 2H2O is another balanced equation. Both options are valid, but given the need to select one, the first one provided (the balanced one) would be appropriate.