Question

Calculate the concentration (mol/L) of 25.5 mL of 7.07 mol/L HCl diluted to 0.500 L with water?

Answer 1

`~~0.36 \ "M"`

Explanation:

Well, we use the "titration equation", as I like to call it, but it is a very common equation, which states that

`V_1c_1=V_2c_2`

• `V_1,V_2` are the volumes of the two solutions

• `c_1,c_2` are the two concentrations of the two solutions

So, we solve for `c_2`, and the equation becomes,

`c_2=(V_1c_1)/V_2`

Now, we plug in our given values, and we get

`c_2=(0.0255color(red)cancelcolor(black)"L"*7.07 \ "mol/L")/(0.5color(red)cancelcolor(black)"L")`

`=0.36057 \ "mol/L"`

`~~03.6 \ "mol/L"`

We can also write this as `0.36 \ "M"`, since `1 \ "M"=1 \ "mol/L"`.