Question #e0ae8

1 Answer
Jun 9, 2017

Answer:

#20. "mL"# should be correct.

Explanation:

This a dilution problem, so we can use the formula

#M_ "conc"V_ "conc" = M_ "dil"V_ "dil"#

where

  • #M_"conc"# is the molar concentration (molarity) of the concentrated, stock solution, and #M_"dil"# is the molar concentration of the dilute solution

  • #V_"conc"# is the volume of the concentrated, stock solution, and #V_"dil"# is the volume of the dilute solution

Let's rearrange the equation to solve for the volume of the stock solution, #V_"conc"#, and plug in our known values:

#V_ "conc" = (M_ "dil"V_ "dil")/(M_ "conc") = ((0.50cancel(M))(100.0"mL"))/(2.5cancel(M)) = color(red)(20."mL"#

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