Use the chemical reaction to answer the question.

Question

​CaCO3→CO2​+CaO

A scientist heats 30 grams of calcium carbonate (CaCO3
) in the chemical reaction shown. What is the total mass of the products?

(1 point)
Responses

30 grams
30 grams

15 grams
15 grams

60 grams
60 grams

10 grams
10 grams

Use the chemical reaction to answer the question.

4​Fe+3O2→2Fe2O3​

What happens to atoms of Fe and O2 during the reaction?
4Fe + 30 2 arrow 2Fe 2 0 3
(1 point)
Responses

They are rearranged.
They are rearranged.

They are lost.
They are lost.

They maintain their properties.
They maintain their properties.

They gain mass.

Which is most likely to occur during a chemical reaction?(1 point)
Responses

New atoms are created.
New atoms are created.

The original substance maintains its properties.
The original substance maintains its properties.

Atoms of the original substance are lost.
Atoms of the original substance are lost.

Mass is conserved.
Mass is conserved.

Use the chemical reaction to answer the question.

NaHCO3+HC2H3O2→NaC2H3O2+H2O+CO2

A student mixes baking soda (NaHCO3
) and acetic acid (HC2H3O2
) to produce a chemical reaction shown. Which statement about the reaction is correct?

(1 point)
Responses

The atoms of the reactants are regrouped during the reaction.
The atoms of the reactants are regrouped during the reaction.

Atoms of Na are destroyed during the reaction.
Atoms of Na are destroyed during the reaction.

There are more H atoms after the reaction.
There are more H atoms after the reaction.

Some atoms gain mass after the reaction.

use the chemical reaction to answer the question.

2H2+O2→2H2O

There are four atoms of hydrogen (H
) before the reaction. How many atoms of hydrogen are present after the reaction?

(1 point)
Responses

2
2

8
8

5
5

4

Answer 1

Let's answer each question based on the chemical reactions provided.

1. For the reaction CaCO3 → CO2 + CaO:

   • According to the law of conservation of mass, the total mass of the reactants equals the total mass of the products. Since 30 grams of calcium carbonate (CaCO3) are heated, the total mass of the products (CO2 and CaO) will also be 30 grams.
   • Correct Answer: 30 grams

2. For the reaction 4Fe + 3O2 → 2Fe2O3:

   • During a chemical reaction, atoms are rearranged to form new substances. The atoms of iron (Fe) and oxygen (O2) rearrange to form iron oxide (Fe2O3).
   • Correct Answer: They are rearranged.

3. What is most likely to occur during a chemical reaction?

   • In a chemical reaction, atoms are conserved; they are neither created nor destroyed, and their total mass remains constant. Thus, mass is conserved in a chemical reaction.
   • Correct Answer: Mass is conserved.

4. For the reaction NaHCO3 + HC2H3O2 → NaC2H3O2 + H2O + CO2:

   • In this reaction, the atoms of the reactants are rearranged to form the products. No atoms are destroyed, and the total number of atoms remains the same before and after the reaction.
   • Correct Answer: The atoms of the reactants are regrouped during the reaction.

5. For the reaction 2H2 + O2 → 2H2O:

   • There are four atoms of hydrogen (H) before the reaction (from 2H2). According to the equation, the number of hydrogen atoms remains the same after the reaction; they are just now part of water (H2O). Therefore, there are still 4 hydrogen atoms present after the reaction.
   • Correct Answer: 4

To summarize:

1. 30 grams
2. They are rearranged.
3. Mass is conserved.
4. The atoms of the reactants are regrouped during the reaction.
5. 4