Law of Conservation of Matter Quick Check

Question

1 of 41 of 4 Items
Question
Suppose 10 atoms of carbon (C) react with 20 atoms of oxygen (O) to form 10 molecules of carbon dioxide ( CO2
). According to the law of conservation of matter, how many atoms are present in this reaction?(1 point)
Responses

20
20

30
30

10
10

15
15
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Answer 1

According to the law of conservation of matter, the number of atoms in a chemical reaction must remain constant before and after the reaction. In this case, you have:

• 10 atoms of carbon (C)
• 20 atoms of oxygen (O)

To find the total number of atoms involved in the reaction, you can simply add the number of carbon and oxygen atoms together:

10 (C) + 20 (O) = 30 atoms total.

Therefore, the correct response is 30.

Answer 2

Which procedure could be used to demonstrate that matter is conserved during a chemical change or reaction?(1 point)
Responses

Find the mass of a piece of paper. Tear the paper into smaller pieces. Find the mass of the pieces.
Find the mass of a piece of paper. Tear the paper into smaller pieces. Find the mass of the pieces.

Find the mass of an acid and a base. Combine them to produce water and a salt. Find the mass of the water and salt.
Find the mass of an acid and a base. Combine them to produce water and a salt. Find the mass of the water and salt.

Find the mass of a log. Burn the log until it turns to ash and smoke. Find the mass of the ash.
Find the mass of a log. Burn the log until it turns to ash and smoke. Find the mass of the ash.

Find the mass of a stick of butter. Heat the butter until it melts. Find the mass of the melted butter.

Answer 3

To demonstrate that matter is conserved during a chemical change or reaction, the most appropriate procedure would be:

Find the mass of an acid and a base. Combine them to produce water and a salt. Find the mass of the water and salt.

This method involves a chemical reaction (acid-base reaction) where the products can be accurately measured, allowing you to compare the mass of the reactants to the mass of the products to show that matter is conserved.

The other options may not effectively show conservation of matter in a chemical reaction:

• Tearing paper is a physical change, not a chemical one.
• Burning a log releases gases (smoke) into the air, making it difficult to measure the total mass of products accurately.
• Melting butter is also a physical change, not a chemical reaction.

Therefore, the second option is the best choice for demonstrating conservation of matter.

Answer 4

What is always true according to the Law of Conservation of Matter?(1 point)
Responses

Atoms created during a chemical reaction must have the same mass as the atoms in the reactants.
Atoms created during a chemical reaction must have the same mass as the atoms in the reactants.

New molecules cannot be formed from the reactants during a chemical reaction.
New molecules cannot be formed from the reactants during a chemical reaction.

The total number of molecules before and after a chemical reaction stays the same.
The total number of molecules before and after a chemical reaction stays the same.

Atoms can be rearranged during a chemical reaction but cannot be added or taken away

Answer 5

The statement that is always true according to the Law of Conservation of Matter is:

Atoms can be rearranged during a chemical reaction but cannot be added or taken away.

This principle means that during a chemical reaction, the total number of atoms remains constant; they are simply rearranged to form new substances. The other options are not correct:

• Atoms created during a chemical reaction cannot be formed from nothing, so they can't have the same mass as reactants if new atoms were to magically appear (which doesn’t happen).
• New molecules can indeed be formed from the reactants during a chemical reaction.
• The total number of molecules before and after a reaction does not necessarily stay the same, as the number of molecules can change, but the total number of atoms remains constant.

Thus, the correct response is that atoms can be rearranged during a chemical reaction but cannot be added or taken away.

Answer 6

A student combines two liquids in a beaker. She observes that the mass of the combined liquid is less than the mass of the two separate liquids. The student claims that this observation shows that matter is not conserved in chemical reactions. Which statement explains why the student’s claim is incorrect?(1 point)
Responses

The product contained fewer atoms than the reactants.
The product contained fewer atoms than the reactants.

The reaction produced a gas that escaped the beaker.
The reaction produced a gas that escaped the beaker.

The combined liquid was warmer than the two separate liquids.
The combined liquid was warmer than the two separate liquids.

The reaction did not change the physical properties of the liquids.

Answer 7

The statement that explains why the student's claim is incorrect is:

The reaction produced a gas that escaped the beaker.

This means that during the reaction, some of the matter (in the form of gas) left the system, which would account for the mass of the combined liquid being less than the mass of the two separate liquids. The Law of Conservation of Matter states that matter cannot be created or destroyed in a closed system; however, if gases escape the system, it can give the appearance that matter is not conserved. The other options do not effectively address the reason for the observed mass change.