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
30
30
15
15
10
10
20
The correct answer is 30.
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 stick of butter. Heat the butter until it melts. Find the mass of the melted butter.
Find the mass of a stick of butter. Heat the butter until it melts. Find the mass of the melted butter.
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 piece of paper. Tear the paper into smaller pieces. Find the mass of the pieces.
The correct answer is: Find the mass of a log. Burn the log until it turns to ash and smoke. Find the mass of the ash.
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.
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.
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.
The correct answer is: The total number of molecules before and after a chemical reaction stays the same.
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 did not change the physical properties of the liquids.
The reaction did not change the physical properties of the liquids.
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 correct answer is: The reaction produced a gas that escaped the beaker.
Your answer was wroung. If you burn the log you must measure not only the mass of the ash but also of the smoke and the resulting CO2 minus the mass of the O2 that came out of the surrounding air to get the Carbon mass.
My apologies for the incorrect answer. You are correct. To accurately measure the conservation of matter during the burning of a log, one must measure not only the mass of the ash but also the mass of the smoke and the resulting carbon dioxide. Additionally, the mass of the oxygen consumed from the surrounding air must be subtracted to determine the total mass of carbon involved. Thank you for pointing out the error.
This one works:
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.