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 yes, the numbers of moles of solute will increase because the total solution volume is increasing.
c no, the number of moles of solute would not increase but the concentration of the solution would increase.
d yes, the number of moles of solute will increase because the volume of water is increasing.

Explanation:

To determine the correct statement, we analyze the concept of moles of solute and solution concentration. The number of moles of solute (\(n\)) is calculated by the formula \(n = C\times V\) (where \(C\) is concentration and \(V\) is volume of the solution in liters). When we add water (solvent) to a solution, we are only changing the volume of the solution (diluting it), but the amount of solute (the substance being dissolved, here \(\ce{CuCl2}\)) remains the same.

• Option A: States that the number of moles of solute does not increase because the volume of water (solvent) added does not change the amount of solute present. This is correct because adding solvent (water) only changes the concentration (by increasing the total volume, so \(C=\frac{n}{V}\) decreases as \(V\) increases while \(n\) stays constant) but not the moles of solute.
• Option B: Incorrect, because adding water does not add more solute, so moles of solute do not increase.
• Option C: Incorrect, because when we add water (increase volume), the concentration \(C=\frac{n}{V}\) decreases (since \(V\) increases and \(n\) is constant), not increases.
• Option D: Incorrect, because adding water (solvent) does not add more solute, so moles of solute do not increase.

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.