Verified answer

37% HCl is approx 12.5molar

You want to prepare 200ml of 10mM HCl That is 0.01M

Use equation:

M1V1 = M2V2

0.01*200= 12.5*V2

V2 = 0.01*200/12.5

V2 = 0.16ml

The answer is: dilute 0.16ml of the concentrated acid to 200ml and you will have a 10mM solution.

I trust that you will realise the impracticality of doing this. It is hardly possible to measure out 0.16ml of the concentrated acid. What you are trying to do is actually bad laboratory practice in that you are trying to prepare a small volume of very dilute solution from a very concentrated solution. This is never an accurate procedure.

A far better way is to predilute the concentrated acid say 100 fold. Measure out 10ml and dilute to 1 litre or 1000ml. Now from this diluted solution you withdraw 100 times what you originally calculated, that is 0.16 *100 = 16ml acid solution, and again dilute this to 200ml.

However, this comes with a warning: 200ml of a 10mM solution is a very precide description of a solution. 37% HCl is a very imprecise description of the concentrated solution. When you have finally made your solution at 10mM concentartion, it is essential to standardise it againd a known acid. You cannot use the solution as a primary standard.

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RE:

Prepare 10mM HCl from 37% HCl?

How can I prepare say 200 ml of 10mM HCl from 37% HCl? M= 36.36g/mol. I am no chemist but I need to prepare this. Thank you.