# Confusion between moles and molarity units

I am a total newbie in the field and i would like some kind of guidance.

So, I have been recently given 2 datasets with measurements regarding several phospholipid fatty acids of plasma HDL. Both datasets consist of the same classes of FAs but with different units of measurement (μΜ and mol%).

Since I have no previous experience with that kind of data, can someone give me a hint about how (and if) it is possible to convert from one unit to the other?

• yes it will be possible as $M$ is $mol dm^{-3}$ Dec 17, 2018 at 10:51
$$\ce{M}$$ is a shortcut for $$\frac{\ce{mol}}{\ce{l}}$$. $$\ce{mol}\%$$ on the other side is defined as $$\frac{n}{n_{\ce{tot}}}$$. In order to convert between the two you need to know the density $$\rho$$ and the molar mass $$M$$ (don't confuse this with the unit) of your solution/mixture. You can then do $$c_{\ce{mol}\%} = \frac{c_\ce{M} \cdot V_{\ce{mix}}}{V_{\ce{mix}} \cdot \rho \cdot M^{-1}} = \frac{c_\ce{M}}{\rho \cdot M^{-1}}$$ $$c_{\ce{mol}\%}$$ is the concentration in $$\ce{mol}\%$$ and $$c_M$$ the one in $$\ce{M}$$.