If the volume of the original sample with concentration 0.25 mg/L is 20 mL, what should be the final volume of solution in order to dilute it to 0.10 mg/L?

i am having a hard time with moles i have tried for hours but still am not able to do it

1 Answer
Apr 14, 2018

The final volume is #"50 mL"#.

Explanation:

Use the dilution equation:

#C_1V_1=C_2V_2#,

where:

#C_1# is the initial concentration, #C_2# is the final concentration, #V_1# is the original volume, and #V_2# is the final volume.

Known

#C_1="0.25 mg/L"#

#V_1="20 mL"#

#C_2="0.10 mg/L"#

Unknown

#V_2#

Solution

Rearrange the equation to isolate #V_2#. Plug in the known values and solve.

#V_2=(C_1V_1)/C_2#

#V_2=(0.25color(red)cancel(color(black)("mg"/"L"))xx20"mL")/(0.10color(red)cancel(color(black)("mg"/"L")))="50 mL"#