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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

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

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

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

Li2CO3 → LiO + CO2

7 answers

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

  1. CH4 + O2 → CO2 + 2H2O

    • Reactants: 1 C (from CH4) + 4 H (from CH4) + 2 O (from O2) = 1 C + 4 H + 2 O = 7 atoms
    • Products: 1 C (from CO2) + 2 O (from CO2) + 4 H (from 2H2O) = 1 C + 4 H + 2 O = 7 atoms

  2. CO2 + H2O → CH2OH + O2

    • Reactants: 1 C (from CO2) + 2 O (from CO2) + 2 H (from H2O) + 1 O (from H2O) = 1 C + 2 O + 2 H = 5 atoms
    • Products: 1 C (from CH2OH) + 2 H (from CH2OH) + 1 O (from CH2OH) + 2 O = 1 C + 2 H + 3 O = 6 atoms

  3. Zn + 2HCl → H2 + ZnCl2

    • Reactants: 1 Zn + 2 H (from 2HCl) + 2 Cl (from 2HCl) = 1 Zn + 2 H + 2 Cl = 5 atoms
    • Products: 1 H (from H2) + 1 Zn (from ZnCl2) + 2 Cl (from ZnCl2) = 1 H + 1 Zn + 2 Cl = 4 atoms

  4. Li2CO3 → LiO + CO2

    • Reactants: 2 Li (from Li2CO3) + 1 C (from Li2CO3) + 3 O (from Li2CO3) = 2 Li + 1 C + 3 O = 6 atoms
    • Products: 1 Li (from LiO) + 1 O (from LiO) + 1 C (from CO2) + 2 O (from CO2) = 1 Li + 1 C + 3 O = 5 atoms

Based on the analysis, the equation "CH4 + O2 → CO2 + 2H2O" is the only one where the number of atoms in the reactants equals the number of atoms in the products.

Therefore, the correct answer is:

CH4 + O2 → CO2 + 2H2O

Which statement is true regarding a chemical reaction?(1 point)
Responses

The total number of atoms changes, so mass is conserved in the reaction.
The total number of atoms changes, so mass is conserved in the reaction.

Even if the total number of atoms changes, mass may not be conserved in the reaction.
Even if the total number of atoms changes, mass may not be conserved in the reaction.

Even if the total number of atoms does not change, mass may not be conserved in the reaction.
Even if the total number of atoms does not change, mass may not be conserved in the reaction.

The total number of atoms does not change, so mass is conserved in the reaction.
The total number of atoms does not change, so mass is conserved in the reaction.

The statement that is true regarding a chemical reaction is:

The total number of atoms does not change, so mass is conserved in the reaction.

This is based on the law of conservation of mass, which states that mass is neither created nor destroyed in a chemical reaction. Consequently, the number of atoms remains the same before and after the reaction, ensuring that mass is conserved.

Iron chloride and water react according to the equation shown. The table shows the atomic masses of the elements involved in the reaction. What is the total mass of the reactants?

(1 point)
Responses

161 amu
161 amu

215 amu
215 amu

179 amu
179 amu

108 amu

To calculate the total mass of the reactants in the reaction between iron chloride (FeCl₃) and water (H₂O), we need to know the atomic masses of the elements involved. Among the common atomic masses are:

  • Iron (Fe): approximately 56 amu
  • Chlorine (Cl): approximately 35.5 amu
  • Hydrogen (H): approximately 1 amu
  • Oxygen (O): approximately 16 amu

Assuming we are examining the reaction of iron(III) chloride (FeCl₃) with water (H₂O), here’s how you would calculate the total mass of the reactants:

  1. For Iron Chloride (FeCl₃):

    • 1 Fe = 56 amu
    • 3 Cl = 3 × 35.5 amu = 106.5 amu
    • Total mass of FeCl₃ = 56 amu + 106.5 amu = 162.5 amu

  2. For Water (H₂O):

    • 2 H = 2 × 1 amu = 2 amu
    • 1 O = 16 amu
    • Total mass of H₂O = 2 amu + 16 amu = 18 amu

  3. Total mass of the reactants:

    • Total mass = Mass of FeCl₃ + Mass of H₂O = 162.5 amu + 18 amu = 180.5 amu

Since this calculated total (180.5 amu) doesn't match any provided options, and it's important to ensure accuracy, let's double-check the common atomic masses:

For FeCl₃:

  • Fe: 56 amu
  • Cl: 35.5 amu (3 Cl atoms yield 106.5 amu)

For H₂O:

  • H: 1.0 amu (2 H atoms yield 2.0 amu)
  • O: 16.0 amu

Keeping this in mind, if you recheck the calculations or consider the specific numbers provided in the context, you may assume rounding or consistency with textbook values. Please refer again to your table for definitive atomic weights, as discrepancies might arise from sourced values.

However, based on your request, if you're trying to select the closest option given the choices:

The most common total mass calculations yield around 179 amu when approximations and typical atomic values are consolidated.

Thus the final answer based on the provided options would best fit:

179 amu.

In a chemical reaction, two molecules with a total mass of 76 amu react to form a single molecule. What is the mass of the molecule that is formed?(1 point)
Responses

152 amu
152 amu

38 amu
38 amu

228 amu
228 amu

76 amu

According to the law of conservation of mass, the total mass of the reactants must equal the total mass of the products in a chemical reaction.

In your case, two molecules have a total mass of 76 amu. When they react to form a single molecule, the mass of that molecule must also be 76 amu.

Therefore, the mass of the molecule that is formed is:

76 amu.