Question

Calculate the empirical formula of the hydrocarbon which has 81.8%carbon and 18.2% Hydoogen.
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Answer 1

Answer:

Please mark me brilliant

Explanation:

Please mark me brilliant

Answer 2

Explanation:

This is an empirical formula problem. To do one, you need to know what mass of each element in the formula you have. Since this one gives % by mass, you will assume you have 100 grams of compound, then the percents given will be the same as the mass in grams of that element in the compound.

So, convert the mass of each element to moles using molar mass of the element (not of the element in a compound, like use mass of H, not that of H2). Then, when you have moles of each element, you must find the mole ratio. To do this, and have the ratio be in reference to the smallest amount of moles of an element present (as formulas have to) you must divide each number of moles by the smallest number of moles. In many cases, you will get whole numbers when you do this, as 1.003 is close enough to round to 1 or 1.998 is close enough to round to 2. But if the ratio comes out not close to a whole number, as ending in 0.1 or 0.2, or 0.25, etc., you will have to multiply each of the ratios by the same number, in order to get whole numbers. Here’s a list from my teaching handout on this topic

If mole ratio ends in 0.1, multiply all the ratios by 10

If mole ratio ends in 0.2, multiply all the ratios by 5

If mole ratio ends in 0.33, multiply all the ratios by 3

If mole ratio ends in 0.4, multiply all the ratios by 5

If mole ratio ends in 0.5, multiply all the ratios by 2

If mole ratio ends in 0.66, multiply all the ratios by 3

If mole ratio ends in 0.75, multiply all the ratios by 4

If mole ratio ends in 0.8, multiply all the ratios by 5

once you have the mole ratios in whole numbers, those numbers are the subscripts of those elements in the formula. For example if you had a compound of oxygen and nitrogen and the ratios came out 2.5 for oxygen and 1 for nitrogen, you’d multiply them both by 2 to get the whole numbers 5 and 2 and the formula N2O5.

Hopefully, you can now do the problem.