# Question #11605

##### 1 Answer

Here's what I got.

#### Explanation:

The trick here is to realize that when performing a **dilution**, the ratio that exists between the concentration of the stock solution and the concentration of the diluted solution is **equal** to the ratio that exists between the volume of the diluted solution and the volume of the stock solution.

So for any dilution calculation, you know that you must have

#"DF" = c_"stock"/c_"diluted" = V_"diluted"/V_"stock" -># thedilution factor

Now, your starting solution has a volume of

As you know, solutions are *homogeneous mixtures*, i.e. they have the same composition throughout, so the

This

After you **dilute** this solution, its final volume is equal to *dilution factor* is equal to

#"DF" = (100 color(red)(cancel(color(black)("mL"))))/(25color(red)(cancel(color(black)("mL")))) = color(blue)(4)#

The volume of the solution **increased** by a factor of **decreased** by a factor of

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

Therefore, you will have

#c_"diluted" = "0.136 M"/color(blue)(4) = color(darkgreen)(ul(color(black)("0.034 M")))#

I'll leave the answer rounded to two **sig figs**, but keep in mind that you only have one significant figure for the final volume of the diluted solution.

As an important note, your stock solution of hydrochloric acid is not that concentrated to begin with, but you should always remember that when diluting concentrated acids, you must **always** add acid to water and **never** water to acid!