Question

Concerning the 10.0 mL of 0.50 M NaCl to 100 mL of solution:
Does dilution change the concentration?

Yes
No

Answer 1

Answer:

Yes

Explanation:

Before dilution:

Volume of NaCl = 10 mL

Concentration of NaCl = 0.5 M

Number of moles = Molarity*Volume = 0.5*10 = 5 millimoles.

Note that number of moles of NaCl does not change on dilution as we are only adding water.

After dilution:

Volume of NaCl = 100 mL

Number of moles = 5 millimoles (no change)

New Concentration = Number of moles per volume in litres = $\frac{5\times10^{-3}}{100\times10^{-3}}$= 0.05 Molar

Hence the concentration became one-tenth of the initial concentration after dilution.