Question

Determine the empirical formula of a compound with the following composition by mass...
62.1% Carbon
5.21% Hydrogen
12.1% Nitrogen
20.59% Oxygen

Answer 1

please! im not just copying and pasting my question, I actually really need help and an explanation

Answer 2

If you would have 100 grams of this compound how many grams would you have of each element?

Answer 3

the percentages, but just as numbers @LeibyStrauss

Answer 4

Correct. So can you convert the grams to moles?

Answer 5

just multiply by 6.02 x 10^21?

Answer 6

6.02 x 10^23 is Avogadro's number, it will give you the number of atoms in a mole. We need to do something else, how many moles are in Carbon, Hydrogen etc. Do you know how many moles are in 63.1 g of Carbon?

Answer 7

there are 12 grams per mole of Carbon, so do I take 63.1 times 12?

Answer 8

*in carbon

Answer 9

How many grams would be in 5 moles of carbon?

Answer 10

60

Answer 11

right?

Answer 12

You have 62.1 g of carbon, (i made a typo earlier it's not 63.1) which will be ~ 5 moles. If you multiply it by 12 you'll get a large number, not 5.

Do you know how to perform dimensional analysis?

Answer 13

i don't think so:/
it's 745.2

Answer 14

Were you taught how to convert from grams to moles?

Answer 15

okay I found the moles for all of them and it's
C: 745.2
H: 5.21
N: 169.4
O: 392.44

Answer 16

yes, i'm just not very good at it

Answer 17

sorry, I meant grams for all of them

Answer 18

You can't have 745.2 mole of C. 1 mole is 12.01 g. 5 mole is 60.05 g. You have 62.1 g so you have around 5 mole. You multiplied and got a high number.

Answer 19

i don't understand. why is that significant?

Answer 20

To find the empirical formula you need to know the number of moles of each element. The number needs to be correct. If you start with 62.1 g of carbon you need the number of moles of carbon to be around 5 (based on the reasoning of the previous post). If you have the wrong number you can't solve the problem.

Answer 21

okay so, it'd be 5.175

Answer 22

OHHHHH I THINK I GET IT

Answer 23

Good. So now calculate the moles of the rest of the elements.

Answer 24

C: 5.2
H.5.2
N: .86
o: 1.3

Answer 25

okay now i don't know what to do

Answer 26

According to your calculations you have \[C _{5.2 mol}H _{5.2mol}N _{0.86 mol}O _{1.3mol}\]
Divide each one by the smallest mole

Answer 27

okay so