Question
Angela performs an experiment in the laboratory. She adds 65.38 grams of zinc dust into a beaker containing 1 M copper sulfate solution. The 1 M copper sulfate solution was prepared by dissolving 159.46 g of copper sulfate in 1 liter of water. She then stirs the reaction mixture briskly and finds that the blue color of the solution fades away.
Because zinc metal is more reactive than copper, it displaces copper from copper sulfate and forms 161.28 g of zinc sulfate in the solution. It also forms a thick deposition of 63.56 g of copper metal at the bottom of the beaker. With constant stirring, it reaches a stage where the solution becomes completely colorless. This indicates that the reaction has reached completion.
Zn
(
s
)
+
CuSO
4
→
ZnSO
4
(
a
q
)
+
Cu
(
s
)
What evidence from this experiment would support the claim that it conserved mass?
A.
The mass of copper deposited at the end of the reaction is nearly the same as the original mass of the zinc.
B.
The number of mols of dissolved solute in the blue solution at the beginning of the reaction is the same as the number of mols of dissolved solute at the end of the reaction.
C.
The number of mols of the dissolved solutes in the colorless solution at the end of the reaction is the same as the copper precipitate.
D.
The mass of the reaction mixture at the end of the reaction is the same as that of the reactants added into the beaker.
Because zinc metal is more reactive than copper, it displaces copper from copper sulfate and forms 161.28 g of zinc sulfate in the solution. It also forms a thick deposition of 63.56 g of copper metal at the bottom of the beaker. With constant stirring, it reaches a stage where the solution becomes completely colorless. This indicates that the reaction has reached completion.
Zn
(
s
)
+
CuSO
4
→
ZnSO
4
(
a
q
)
+
Cu
(
s
)
What evidence from this experiment would support the claim that it conserved mass?
A.
The mass of copper deposited at the end of the reaction is nearly the same as the original mass of the zinc.
B.
The number of mols of dissolved solute in the blue solution at the beginning of the reaction is the same as the number of mols of dissolved solute at the end of the reaction.
C.
The number of mols of the dissolved solutes in the colorless solution at the end of the reaction is the same as the copper precipitate.
D.
The mass of the reaction mixture at the end of the reaction is the same as that of the reactants added into the beaker.
Answers
GPT-4o mini
To determine which evidence supports the claim that mass is conserved during the experiment, we need to consider the principle of conservation of mass, which states that in a closed system, the mass of the reactants should equal the mass of the products.
Let's analyze the options:
**A. The mass of copper deposited at the end of the reaction is nearly the same as the original mass of the zinc.**
While this option suggests a relationship between the mass of zinc and the mass of the copper deposited, it does not provide direct evidence of total mass conservation of the system, as it does not consider all components of the reaction (the mass of solution, zinc sulfate, etc.).
**B. The number of mols of dissolved solute in the blue solution at the beginning of the reaction is the same as the number of mols of dissolved solute at the end of the reaction.**
This statement addresses the dissolved solutes but does not account for the mass of solid reactants and products, therefore not sufficiently supporting overall mass conservation.
**C. The number of mols of the dissolved solutes in the colorless solution at the end of the reaction is the same as the copper precipitate.**
This option also focuses on the number of moles of dissolved ions and does not encompass the overall mass of reactants and products, falling short of demonstrating mass conservation.
**D. The mass of the reaction mixture at the end of the reaction is the same as that of the reactants added into the beaker.**
This option most clearly supports the claim of mass conservation. It directly compares the total mass of the system before and after the reaction, aligning with the conservation of mass principle.
Therefore, the correct answer is:
**D. The mass of the reaction mixture at the end of the reaction is the same as that of the reactants added into the beaker.**
Let's analyze the options:
**A. The mass of copper deposited at the end of the reaction is nearly the same as the original mass of the zinc.**
While this option suggests a relationship between the mass of zinc and the mass of the copper deposited, it does not provide direct evidence of total mass conservation of the system, as it does not consider all components of the reaction (the mass of solution, zinc sulfate, etc.).
**B. The number of mols of dissolved solute in the blue solution at the beginning of the reaction is the same as the number of mols of dissolved solute at the end of the reaction.**
This statement addresses the dissolved solutes but does not account for the mass of solid reactants and products, therefore not sufficiently supporting overall mass conservation.
**C. The number of mols of the dissolved solutes in the colorless solution at the end of the reaction is the same as the copper precipitate.**
This option also focuses on the number of moles of dissolved ions and does not encompass the overall mass of reactants and products, falling short of demonstrating mass conservation.
**D. The mass of the reaction mixture at the end of the reaction is the same as that of the reactants added into the beaker.**
This option most clearly supports the claim of mass conservation. It directly compares the total mass of the system before and after the reaction, aligning with the conservation of mass principle.
Therefore, the correct answer is:
**D. The mass of the reaction mixture at the end of the reaction is the same as that of the reactants added into the beaker.**