### Fundamentals M.25 Help

Posted: **Thu Oct 06, 2016 10:48 am**

by **Dominique Zuk 1G**

Though I've looked through the solutions manual for this problem (M.25 Fundamentals section), I still don't conceptually understand why the particular steps were taken to solve for the percent purity. We were given percentages of C (77.48%) and H (5.20%) that were present in the sample, and must calculate the percentage purity by mass of the sample. Why/How does one first approach this problem?

### Re: Fundamentals M.25 Help [ENDORSED]

Posted: **Thu Oct 06, 2016 12:37 pm**

by **mikezargari**

So you know that if the only molecule present was the 2-naphthol your percent of carbon would be 10(because you have 10 carbon atoms) times 12 grams/mol of carbon all divided by 144.16 g/mol( molar mass of 2-naphthol). Multiply whatever decimal you get by 100 and you well get your percentage of carbon. You can similarly calculate the percent of hydrogen. Your percentages are going to be higher because in our calculations the LiBr was not present.Now, take the percent purity that was given to you and divide it by your theoretical purity that you calculated and multiply by 100. Do this for both carbon and hydrogen and you should be fine.