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
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
#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.