A compound is composed of 85.6% Carbon and the rest is Hydrogen. The molecular mass of the compound is 42.078g/mol. What is the

Question

3 years ago

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molecular formula for the compound?

1 answer:

s344n2d4d5 [400] · Answer 1 · 2022-08-03T23:31:45+03:00

The molecular formula for the compound is $C_{3} H_{6}$

<u>Explanation</u>:

As with all of these problems, we assume 100 g of an unknown compound.

And thus, we determine the elemental composition by the given percentages.

Moles of carbon = 85.64 / 12.011

= 7.13 mol.

Moles of hydrogen = 14.36 / 1.00794

= 14.25 mol.

There are 2 moles of hydrogen per mole of carbon. And thus the empirical formula is CH $_{2}$ .

And molecular formula = n × (empirical formula)

Thus, 42.08 = n × (12.011 + 2 × 1.00794)

And thus n = 3, and molecular formula = $C_{3} H_{6}$