molarity and stock solution problem

Derinda · Post by **Derinda** » Tue Apr 29, 2008 11:24 am

How do I find what molarity should the stock solution be if you want to dilute 25.0mL to 2.00L and have the final concentration be 0.103 M?

sharan · Post by **sharan** » Tue Apr 29, 2008 2:01 pm

hey

use M₁V₁ = M₂V₂

so you hv
0.025 L * M₁ = .103 * 2L
M₁ = .103 * 2 / 0.025
M₁= 8.24
The original stock shud be 8.25 M

Hope this helps,

Derinda · Post by **Derinda** » Tue Apr 29, 2008 4:02 pm

Just want to double check something. Do you mean the original stock should be 8.25 or 8.24 as in M₁= 8.24. Also is M₁ always the stock or cant he stock be either M₁ or M₂? Thank you very much for your help.

sharan · Post by **sharan** » Tue Apr 29, 2008 4:17 pm

Hey
oops my bad i meant 8.24 u can do the calculation

Secondly, No it doesnt matter which is M₁ or M₂. It could be either one you just have to make sure that if you are considering stock solution as M₁, V₁ has to be the volume of vice versa. Or in other words, subscript 1 or 2 should refer to same thing. I hope that make sense and sorry for any confusion.

sharan · Post by **sharan** » Tue Apr 29, 2008 4:35 pm

what i meant to say was
"It could be either one you just have to make sure that if you are considering stock solution as M₁, V₁ has to be the volume of the stock solution or vice versa. sorryy again...