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Re: ml and cm^3



Robert Cohen asks, "Isn't 1 ml equivalent to 1 cm^3? Isn't g/ml
equivalent to g/cm^3?"

I think it depends upon whom you ask. Now that we have a meter (and
from that, centimeter) defined by light, it turns out that 1 cm^3 of
water, at water's maximum density (at 3.98 Celsius) is not exactly one;
rather, it is 0.999972 g/cm^3. Therefore, water never gets more dense
than this, i.e. it never reaches exactly one. For chemists it is most
convenient to calibrate volumes using mass of water. Therefore chemists
still want one milliliter of water at 3.98 Celsius to come out exactly
one gram.

My Merck Index says... density of water at 3.98 Celsius = 1.000000 g/ml
= 0.999972 g/cc. However, I believe NIST does define one liter (and
from that, ml) as one cubic decimeter. I don't know what the latest
word is, but in chemistry circles the people and texts I am familiar
with make a slight distinction between ml and cm^3. Does anyone have
updated information on that?

Michael D. Edmiston, Ph.D.
Professor of Physics and Chemistry
Chair of Sciences
Bluffton College
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu