A sample of toluene, C7H8 has a mass of 74.5 g.

a) how many molecules does the sample contain?
b) How many carbon atoms does it contain? How many hydrogen atoms does it contain?

My work
For b would it be 7 carbon atoms and 8 hydrogen atoms

If it weighs any number of grams it has millions of atoms even if it is URANIUM!!!!!

6.02 * 10^23 molecules/mol
Avagadro's constant

7 C = 84 g/mol
8 H = 8 g/mol
so 92 g/mol

(74.5/92) * 6*10^23 = 4.86 *10^23 MOLECULES

7 times that many C atoms
8 imes that many H atoms

So would i multiply 4.86 x 10^23 by 7 to get the number of carbon atoms

And multiply by 8 to get the number of hydrogen atoms

To calculate the number of molecules in a sample, you need to use Avogadro's number, which is approximately 6.022 x 10^23 molecules per mole.

To find the number of molecules in the sample of toluene, follow these steps:

a) Calculate the number of moles of toluene in the sample using its molar mass. The molar mass of toluene (C7H8) is:
(7 carbon atoms x 12.01 g/mol) + (8 hydrogen atoms x 1.01 g/mol) = 92.14 g/mol

Number of moles = mass of the sample / molar mass
Number of moles = 74.5 g / 92.14 g/mol ≈ 0.808 mol

b) Once you know the number of moles, you can calculate the number of molecules. Multiply the number of moles by Avogadro's number:

Number of molecules = Number of moles x Avogadro's number
Number of molecules = 0.808 mol x (6.022 x 10^23 molecules/mol) ≈ 4.871 x 10^23 molecules

So, the sample of toluene contains approximately 4.871 x 10^23 molecules.

For part b of the question, to determine the number of carbon and hydrogen atoms in the sample of toluene, you need to know the molecular formula. In this case, the toluene formula is C7H8.

From the formula, we can see that toluene contains 7 carbon atoms and 8 hydrogen atoms. So your answer is correct:
The sample of toluene contains 7 carbon atoms and 8 hydrogen atoms.