0
$\begingroup$

How would my sample be affected if the sample was not totally dry? What would happen to the mass percent composition? I believe that it will increase but someone argues that due to ratios, it will decrease.

$\endgroup$
  • $\begingroup$ If sample is not fully dry, obviously this would increase the mass or weight of sample. $\endgroup$ – Khan Aug 28 '16 at 4:14
2
$\begingroup$

The IUPAC Compendium of Chemical Terminology defines the mass fraction $w$ as the

mass of a constituent divided by the total mass of all constituents in the mixture

$$w_i = \frac{m_i}{\sum\limits_{i=1}^{N}m_i} \tag{1}$$

This means that $w_i$ can adopt values between 0 ( = 0 %) when the compound in question is not contained in the sample), and 1 ( = 100 %) when the sample only consists of the compound.

If your sample isn't totally dry, the mass of water adds to the total mass of the sample.

As a result, the denominator in $(1)$ will become larger and the mass fraction $w_i$ for any component (except the water) will decrease.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.