Law of Conservation of Matter Quick Check
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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
10
10
15
15
20
20
30
30
To answer this question, we need to first determine the number of carbon and oxygen atoms present in the reaction, and then consider how they combine to form carbon dioxide.
Given that there are 10 carbon atoms and 20 oxygen atoms, let's start with the carbon atoms:
- Each molecule of carbon dioxide (CO2) contains 1 carbon atom.
- Therefore, 10 molecules of carbon dioxide would contain 10 carbon atoms.
Next, let's consider the oxygen atoms:
- Each molecule of carbon dioxide (CO2) contains 2 oxygen atoms.
- Therefore, 10 molecules of carbon dioxide would contain 20 oxygen atoms.
Adding the number of carbon atoms and oxygen atoms together, we find that there are a total of 30 atoms present in this reaction.
Law of Conservation of Matter Quick Check
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Question
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 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 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 stick of butter. Heat the butter until it melts. Find the mass of the melted butter.
The correct procedure that could be used to demonstrate that matter is conserved during a chemical change or reaction is:
- Find the mass of a log. Burn the log until it turns to ash and smoke. Find the mass of the ash.
Law of Conservation of Matter Quick Check
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Question
What is always true according to the Law of Conservation of Matter?(1 point)
Responses
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.
New molecules cannot be formed from the reactants during a chemical reaction.
New molecules cannot be formed from the reactants during a chemical reaction.
Atoms can be rearranged during a chemical reaction but cannot be added or taken away.
Atoms can be rearranged during a chemical reaction but cannot be added or taken away.
Atoms created during a chemical reaction must have the same mass as the atoms in the reactants.
The correct answer is:
Atoms can be rearranged during a chemical reaction but cannot be added or taken away.
Law of Conservation of Matter Quick Check
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Question
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 combined liquid was warmer than the two separate liquids.
The combined liquid was warmer than the two separate liquids.
The reaction produced a gas that escaped the beaker.
The reaction produced a gas that escaped the beaker.
The reaction did not change the physical properties of the liquids.
The reaction did not change the physical properties of the liquids.
The product contained fewer atoms than the reactants.
The correct statement that explains why the student's claim is incorrect is:
The reaction produced a gas that escaped the beaker.
This is because when a gas is produced during a chemical reaction and escapes the container, it can lead to a decrease in mass, giving the illusion that matter is not conserved. However, matter is still conserved as the gas that escaped is still a part of the overall reaction and will contribute to the total mass of the products and reactants.