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

Question

Responses

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

CO2 + H2O → CH2OH + O2

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

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.

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.

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.

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

Use the equation and the table to answer the question.

FeCl3 + 3H2O → Fe(OH)3 + 3HCl

Element Mass of an Atom (amu)
Fe 56
Cl 35
H 1
O 16
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

179 amu
179 amu

108 amu
108 amu

215 amu
215 amu
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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

76 amu
76 amu

38 amu
38 amu

228 amu
228 amu
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Answer 1

1. In which chemical equation is the number of atoms in the reactants the same as the number of atoms in the products?

   • The correct response is: Zn + 2HCl → H2 + ZnCl2
     (In this equation, there are 3 Zn, 2 H, and 2 Cl on the left, which equals 3 Zn, 2 H, and 2 Cl on the right)

2. Which statement is true regarding a chemical reaction?

   • The correct response is: The total number of atoms does not change, so mass is conserved in the reaction.
     (This reflects the law of conservation of mass, which states that mass is conserved in a chemical reaction; the number of atoms remains the same, hence mass is conserved.)

3. What is the total mass of the reactants in the chemical reaction

   • FeCl3 + 3H2O → Fe(OH)3 + 3HCl?
   • Calculating the total mass of the reactants:
     • FeCl3: 56 (Fe) + (3 × 35) (for Cl) = 56 + 105 = 161 amu
     • 3H2O: 3 × (2 × 1 + 16) = 3 × 18 = 54 amu
     • Total mass of reactants = 161 amu (FeCl3) + 54 amu (3H2O) = 215 amu
   • The correct response is: 215 amu

4. 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?

   • According to the law of conservation of mass, the mass of the products must equal the mass of the reactants.
   • Therefore, the mass of the molecule formed is 76 amu.
   • The correct response is: 76 amu