To determine which chemical equation has the same number of atoms in the reactants as in the products, we need to compare the total number of each type of atom on both sides of the equation.
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Zn + 2HCl → H2 + ZnCl2
- Reactants: Zn (1), H (2 from 2 HCl), Cl (2 from 2 HCl) = 1 Zn + 2 H + 2 Cl
- Products: H (2 from H2), Zn (1 from ZnCl2), Cl (2 from ZnCl2) = 1 Zn + 2 H + 2 Cl
- Total: Both sides have 1 Zn, 2 H, and 2 Cl. This equation is balanced.
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Li2CO3 → LiO + CO2
- Reactants: Li (2 from Li2CO3), C (1 from Li2CO3), O (3 from Li2CO3) = 2 Li + 1 C + 3 O
- Products: Li (1 from LiO), O(1 from LiO), C (1 from CO2), O (2 from CO2) = 1 Li + 1 C + 3 O
- Total: Reactants have 2 Li, products have 1 Li, they are not equal.
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CH4 + O2 → CO2 + 2H2O
- Reactants: C (1 from CH4), H (4 from CH4), O (2 from O2) = 1 C + 4 H + 2 O
- Products: C (1 from CO2), H (4 from 2H2O), O (2 from CO2, 2 from 2H2O = 4 O) = 1 C + 4 H + 4 O
- Total: 4 Oxygen atoms on the product side vs. 2 in the reactant side. They are not equal.
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CO2 + H2O → CH2OH + O2
- Reactants: C (1 from CO2), O (2 from CO2, 1 from H2O), H (2 from H2O) = 1 C + 3 O + 2 H
- Products: C (1 from CH2OH), O (1 from CH2OH, 2 from O2), H (2 from CH2OH) = 1 C + 3 O + 2 H
- Total: Both sides have 1 C, 3 O, and 2 H. This equation is balanced.
After analyzing all the reactions, the balanced chemical equations are:
- Zn + 2HCl → H2 + ZnCl2
- CO2 + H2O → CH2OH + O2
Both equations have the same number of atoms in the reactants and products.