Question

Ethanol has the chemical formula C2 H6 O . A sample of ethanol contains 164grams of C. How many molecules are in the sample? (4.11E24 molecules C2 H6 O)

Answer 1

We have 8.22
`*` 1
`0^(24)` C atoms

We have 4.11
`*` 1
`0^(24)` ethanol molecules

Step-by-step explanation:

Step 1: Data given

Molecular formula of ethanol =
`C_(2) H_(6) O`

Mass of C = 164 grams

Molar mass C = 12.01 g/mol

Step 2: Calculate moles C

Moles C = mass C / molar mass C

Moles C = 164 grams / 12.01 g/mol

Moles C = 13.66 moles

Step 3: Calculate molecules of C

Atoms C = moles C
`*` number of Avogadro

Atoms C = 13.66 moles
`*` 6.02
`*` 1
`0^(23)` molecules/ mol

Atoms C = 8.22
`*` 1
`0^(24)` C atoms

Step 4: Calculate molecules in the sample

For 1 mol
`C_(2) H_(6) O` we have 2 moles C

For 13.66 moles C we have 13.66/ 2 = 6.83 moles
`C_(2) H_(6) O`

Molecules
`C_(2) H_(6) O` = 6.83 moles
`*` 6.02
`*` 1
`0^(23)` = 4.11
`*` 1
`0^(24)` molecules.