Molecular Weight for nucleotides

mountain

When it says; "Molecular Weight: daltons (g/M)" What does daltons mean and what does (g/M) stand for? Does g/M stand for g/mol or what?

How can they calculate Molecular Weight for nucleotides?


Thanks for any inputs.

Monique

A dalton is an atomic mass. For instance C12 has a mass of 12.0000 Da. The mw is the mass of 1 mole of a particular molecule. By definition 1 mole of carbon atoms weighs 12 grams.

mountain

Thanks.

But what does M stand for in g/M?

Moonbear

You had it right...mole.

gerben

(why only four zeros?)

(1) C12 has a mass of 12 Da (by definition; exactly 12, there is no uncertainty)
(2) a mol of C12 atoms weighs 12 grams (by definition)

From (1) and (2) it follows that a dalton is the number of grams that go into a mol (gram/mol)
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(1) C12 = 12 Da <--> mol C12 = mol 12 Da
(2) mol C12 = 12 gram
(substitute 2 into 1) 12 gram = mol 12 Da <--> gram/mol = Da

kalladin

doesn't g/M mean g/mol/L?

cronxeh

its not exactly 12, and its not exactly 16 for oxygen either

but they decided to make it 12 anywho. so just use 12 as a whole number

6 protons = 6 x 1.007277 6.043662
6 neutrons = 6 x 1.008665 6.051990
6 electrons = 6 x 0.000548 0.003288
Total 12.098940

Monique

Carbon was easy to purify, that is why they used it as a reference and why it is the whole number 12.