## anonymous 4 years ago 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.

1. abb0t

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.

2. anonymous

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

3. anonymous

so would the units be g/mol?

4. abb0t

Divide the mol given by 0.745 for both.

5. abb0t

0.0745*

6. anonymous

so not by the molecular mass?

7. abb0t

No. That's for molecular formula. Sorry.

8. abb0t

like information to osrt of "check"

9. anonymous

okay so i got 1 for carbon and 1.4 for hydrogen

10. abb0t

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

11. anonymous

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

12. abb0t

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

13. abb0t

You should have: $\frac{ 546.9g }{ 13.018g }$

14. anonymous

how did you get 13.018?

15. abb0t

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

16. anonymous

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

17. abb0t

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

18. anonymous

so multiply 42.01 with 1 or 2?

19. abb0t

42(empirical formula)

20. anonymous

what is the empirical formula though? 1 or 2?

21. abb0t

1!

22. anonymous

so its just 42.01..

23. abb0t

Use whole numbers. So 42.

24. anonymous

so thats it?