Urgent Purty Problem

[physicsss]

A sample of C10H7OH was found to be contaminated with a small amount of LiBr. The combustion analysis of the sample gave the following results: 77.48% C and 5.20% H. Assume that the only species present are C10H7OH and LiBr, calculate the percentage purity by mass of the sample.

First of all, what is the percentage of purity by mass...? And second, does it mean that 100%-77.48%-5.20% gives the percentage of O and LiBr?

[Gokul43201]

First of all, what is the percentage of purity by mass...? And second, does it mean that 100%-77.48%-5.20% gives the percentage of O and LiBr?If you had 100g of the sample and found that it contained x grams of LiBr, then the percentage purity would be 100-x.

From the formula of the compound, can you not determine how much O there is in it ?