# Basic question

Hiranya S. Roychowdhury hroychow at NMSU.EDU
Fri Mar 5 16:02:11 EST 1999

```At 10:47 AM 3/5/99 -0700, Neal Robert Melvin wrote:
>Can someone tell me what the difference is between a mM unit and a mmol?
>How do you calculate mol?
>
>
>
>Neal Melvin
>University of Calgary - Faculty of Medicine
>Department of Neuroscience - Neuroscience Research Group (NRG)
>Health Sciences Centre
>3330 Hospital Drive, NW
>T2N 4N1
>
>e-mail: nrmelvin at acs.ucalgary.ca
>Phone: (403) 220-4490 (lab)
>       (403) 220-7035 (office)
>       (403) 283-8731 (fax)
>

Hello,
This is an alumnus of U of C responding. Here goes:
M = molar= unit of concentration

when you dissolve a mole of a substance in a litre, you get a
standard solution of 1M (one molar) concentration.

mole= mole= unit of absolute mass.

a mole is the molecular mass of a substance in grams. Thus, a mole
of pure common salt (NaCl) is 58.44g. By the above example, therefore, 1mM
solution of NaCl will contain 1 mmole/litre or 0.05844g= 58.44mg of the
compound. If you sampled 1mL of this solution, you would find a total of 1
micromole or .001 mmole of NaCl in it.

Dr. Hiranya Sankar Roychowdhury
GENE LAB/ EPPWS
New Mexico State University
Las Cruces, NM 88003
Ph. (505) 646-5785
hroychow at nmsu.edu

```