Question

if more water was added to a 3m cucl₂ solution to the 100ml mark, would the number of moles of solute in that beaker change? which one of the following statements is correct?
a no, the number of moles of solute would not increase because the volume of water has no effect on the number of moles of solute.
b no, the number of moles of solute would not increase but the concentration of the solution would increase.
c yes, the numbers of moles of solute will increase because the total solution volume is increasing.
d yes, the number of moles of solute will increase because the volume of water is increasing.

Explanation:

When water is added to a solution (dilution), only the volume of the solution changes. The amount of solute (in moles) remains constant because we are not adding or removing any of the solute itself. The concentration ($C=\frac{n}{V}$, where $n$ is moles of solute and $V$ is volume of solution) will decrease as $V$ increases (since $n$ is constant).

• Option A: Correct. Adding water (changing $V$) does not affect $n$ (moles of solute).
• Option B: Incorrect. Concentration ($C = \frac{n}{V}$) will decrease as $V$ increases (since $n$ is constant), not increase.
• Option C: Incorrect. $n$ (moles of solute) does not increase when only water (solvent) is added.
• Option D: Incorrect. $n$ (moles of solute) is independent of the volume of water (solvent) added as long as no solute is added or removed.

Answer:

A. No, the number of moles of solute would not increase because the volume of water has no effect on the number of moles of solute.