# Question #59b26

##### 1 Answer

#### Explanation:

The trick here is to realize that diluting a solution will cause its concentration to **decrease** by the factor as its volume **increases**.

#"DF" = V_"diluted"/V_"stock" = c_"stock"/c_"diluted"#

Here **dilution factor**.

In your case, the volume of the stock solution increases by

#V_"diluted" = "125 mL" + "875 mL"#

#V_"diluted" = "1,000 mL"#

This means that the dilution factor is equal to--remember, we're using the volume of the diluted solution and the volume of the stock solution here!

#"DF" = ("1,000" color(red)(cancel(color(black)("mL"))))/(125color(red)(cancel(color(black)("mL")))) = color(blue)(8)#

So if the volume **increased** by factor of **decreased** by a factor of

#color(blue)(8) = c_"stock"/c_"diluted"#

You will thus have

#c_"diluted" = c_"stock"/color(blue)(8)#

#c_"diluted" = "0.400 M"/color(blue)(8) = color(darkgreen)(ul(color(black)("0.05 M")))#

The answer is rounded to one **significat figure** because when you're adding the two volumes, the answer, i.e.