Consider a sample of 10.0 g of the gaseous hydrocarbon C2H6 to answer the following question: How many carbon atoms are present in a 10.0 g sample? (The question is asking for the number of carbons in the sample, not the molecule).

Question

When answering the question, include the following:

- State how to find the number of atoms for carbon in a 10.0 g sample.
- State how you know if you need to multiply or divide by Avogadro’s number.
- Give the correct number of significant figures and explain why the answer has that many significant figures.
- Give the numerical answer.

Do I multiply 10 as if I were figuring out the problem just being C2H6?

Answer 1

find moles ... 10.0 g / molar mass

there are two C atoms per molecule
... two moles of C for each mole of C2H6

moles of C = 2 * (moles of C2H6)

C atoms = (moles C) * (Avogadro's number)