Question

4. Carotene, the pigment responsible for the color of carrots, has a percent composition of 89.49%--C and 10.51%--H. Its molecular mass was found to be 546.9g. Calculate its empirical formula and its molecular formula.

Answer 1

Assuming 100% composition you would take 0.8949g of carbon and 0.1051 g of hydrogen.

You then take the molecular mass given to find moles.

Answer 2

ok so Carbon has .0745 mol and hydrogen has .1043 mol. now what do i do?

Answer 3

so would the units be g/mol?

Answer 4

Divide the mol given by 0.745 for both.

Answer 5

0.0745*

Answer 6

so not by the molecular mass?

Answer 7

No. That's for molecular formula. Sorry.

Answer 8

like information to osrt of
"check"

Answer 9

okay so i got 1 for carbon and 1.4 for hydrogen

Answer 10

ok, round to the closest whole number ratio and that's your empirical formula

Answer 11

okay so what about the molecular formula? and so the empirical formula would be just 1 and 1?

Answer 12

Find the total mass of your empirical formula and divide that total by your molecular mass found out.

Answer 13

You should have: \[\frac{ 546.9g }{ 13.018g }\]

Answer 14

how did you get 13.018?

Answer 15

Well, your empirial formula give is CH.
The total mass of C + H = 13.018 g/ mol

Answer 16

okay so the answer to 546.9g/13.018g is 42.01.

Answer 17

Yep, now multiply that number by your empirical formula to get your molecular formula.

Answer 18

so multiply 42.01 with 1 or 2?

Answer 19

42(empirical formula)

Answer 20

what is the empirical formula though? 1 or 2?

Answer 21

1!

Answer 22

so its just 42.01..

Answer 23

Use whole numbers. So 42.

Answer 24

so thats it?