Conservation in Chemical Reactions Quick Check

Question

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Question
In which chemical equation is the number of atoms in the reactants the same as the number of atoms in the products?(1 point)
Responses

CO2 + H2O → CH2OH + O2
CO 2 + H 2 O → CH 2 OH + O 2

Li2CO3 → LiO + CO2
Li 2 CO 3 → LiO + CO 2

Zn + 2HCl → H2 + ZnCl2
Zn + 2HCl → H 2 + ZnCl 2

CH4 + O2 → CO2 + 2H2O
CH 4 + O 2 → CO 2 + 2H 2 O

Answer 1

To determine which chemical equation has the same number of atoms in the reactants and products, we need to analyze each equation.

1. 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: 6 (from CH2OH)
     • Total: 1 C + 3 O + 6 H = 10 atoms
   • Does not balance.

2. 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 (1 from LiO + 2 from CO2)
     • Total: 1 Li + 1 C + 3 O = 5 atoms
   • Does not balance.

3. 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: 2 H + 1 Zn + 2 Cl = 5 atoms
   • Balances.

4. 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 2H2O + 1 from CO2)
     • Total: 1 C + 4 H + 3 O = 8 atoms
   • Does not balance.

The only equation that has the same number of atoms in the reactants and products is:

Zn + 2HCl → H2 + ZnCl2