200. mL of a 12.0% (m/v) NaCl solution is diluted to 600. mL. The new concentration is ________ %?

1 Answer

• If you're diluting 200 mL in a total of 600 mL, that's a dilution of 200/600 = 1/3.

  So the percentage of NaCl = 12 * (1/3) = 4%.

  Another way :

  C1 * V1 = C2 * V2

  C1 = initial concentration = 12%

  V1 = initial volume = 200 mL

  C2 = final concentration (unknown)

  V2 = final volume = 600 mL

  Substituting : 12 * 200 = C2 * 600

  Therefore, C2 = 12 * 200 / 600 = 4%.