## Molarities, concentrations and ratios

**Moderators:** honeev, Leonid, amiradm, BioTeam

- bravebeaker
- Garter
**Posts:**44**Joined:**Sun May 08, 2011 3:26 am**Location:**Kobe, Japan

### Molarities, concentrations and ratios

Hi everyone,

I am a newbie on all this stuff and I need to do some calculations but I am out of adequate knowledge. I tried to search most of the forums here before posting, I apologize in advance if its a double post.

My question is if I need to add 50 uM of solution A to 50 ml of solution B and I need the ratio to be 1:1000 (A:B) how much volume do I need if the bottle of A has a label of 50 mM?

My second question is I need to use solution C which has a label of 3 uM in 500 ml. How much should I take to obtain 300 mM and add to solution B which is 50 ml?

I hope I addressed my questions in a clear way.

Looking forward to hearing from all of respected members..

I am a newbie on all this stuff and I need to do some calculations but I am out of adequate knowledge. I tried to search most of the forums here before posting, I apologize in advance if its a double post.

My question is if I need to add 50 uM of solution A to 50 ml of solution B and I need the ratio to be 1:1000 (A:B) how much volume do I need if the bottle of A has a label of 50 mM?

My second question is I need to use solution C which has a label of 3 uM in 500 ml. How much should I take to obtain 300 mM and add to solution B which is 50 ml?

I hope I addressed my questions in a clear way.

Looking forward to hearing from all of respected members..

Second one is less clair if sol C is 3 uM, is more diluted than 300mM so never you can get a 300mM sol starting of 3uM sol. But the inverse yes you can obtain a 3uM sol from a 300mM one. 300mM=300000uM so diluting 100000times you will get a 3 uM sol., so for 50ml you have to add 100000 times less volume that is the same that 0.5 ul. Hope that this helps you and don´t create more confusion. Buena suerte

let's try to make it a little easier. If you have change in units like from M to mM or mM to uM, that is 1000-times dilution, thus for every 1 ml you add 1 ul or for every 1 l you add 1 ml etc. I think this should make things easier.

Thus in the second case, if it was to make 3 uM solution from 300 mM one (since otherwise it makes no sense, as said protold already), you have to dilute it first from 300 mM to 3 mM, that is 100-times and then from 3 mM to 3 uM, which is 1000-times. Thus, if your finel volume is 50 ml, you add 1/1000, which is 50 ul, but then you need even 100-times less, thus 0.5 ul.

Hopefully that helps

Thus in the second case, if it was to make 3 uM solution from 300 mM one (since otherwise it makes no sense, as said protold already), you have to dilute it first from 300 mM to 3 mM, that is 100-times and then from 3 mM to 3 uM, which is 1000-times. Thus, if your finel volume is 50 ml, you add 1/1000, which is 50 ul, but then you need even 100-times less, thus 0.5 ul.

Hopefully that helps

http://www.biolib.cz/en/main/

*Cis*or*trans*? That's what matters.- bravebeaker
- Garter
**Posts:**44**Joined:**Sun May 08, 2011 3:26 am**Location:**Kobe, Japan

### Who is online

Users browsing this forum: No registered users and 11 guests