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# Confused about mM and mmols and ml and L

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### #1 tihong10

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Posted 20 November 2010 - 01:50 PM

Ok so I am confused about mM, I understand that 1M = 1mol/L and I am fairly certain that 1mM = 1mmol/1L (please correct me on this if I am wrong). But I do remember a problem where e.g. 1mole was divided by 50 ml and the resulting unit was mM...is this right? Please help and include any example problems too that would clarify, Thanks!

### #2 pcrman

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Posted 20 November 2010 - 11:07 PM

>> Ok so I am confused about mM, I understand that 1M = 1mol/L and I am fairly certain that 1mM = 1mmol/1L
You are right.

>>But I do remember a problem where e.g. 1 mole was divided by 50 ml and the resulting unit was mM...is this right?

Here the question is whether 1 mole is quantity (solute) or concentration (solution). If it is quantity, you add 1 M solute into 50 ml solvent, you will get a 20 M solution (1 M / 0.05L = 20 M/L). If it is concentration, you have to give the amount to calculate the final concentration.

### #3 ujla80

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Posted 24 November 2010 - 03:31 PM

please make it clear...is it 1mole solute in 50 ml solvent? if it is so then answer should be 20 M or 20000mM.

tihong10, on 20 November 2010 - 01:50 PM, said:

Ok so I am confused about mM, I understand that 1M = 1mol/L and I am fairly certain that 1mM = 1mmol/1L (please correct me on this if I am wrong). But I do remember a problem where e.g. 1mole was divided by 50 ml and the resulting unit was mM...is this right? Please help and include any example problems too that would clarify, Thanks!

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