Question

What are the emparical and
molecular formulas for a compound
with 83.625% carbon and 16 3 75%
hydrogen and a molecular
weight of 388.78?​

Answer 1

Answer:

ohuojpcjpcjchocu9xu0youfpgu0f0ufy969ypcpucpucupcupcupfupcpufufuodpufupfyofpufyoxupfpufupfupfupfupxyoxyofpuf

Answer 2

Answer:

For this kind of problem, you can assume that the weight of the unknown sample is 100g ( since 75%

C

+ 25%

H

= 100%).

Thus,

weight of

C

= 75g

weight of

H

= 25g

Since chemical formulas deal with number of moles rather than weight in grams, you need to convert each element by multiplying it to their respective atomic masses.

atomic mass of

C

=

12.01

g

mol

atomic mass of

H

=

1.01

g

mol

Thus,

mol

C

= 75

grams

x

1 mol

12.01

grams

= 6.245 mol

C

mol

H

= 25

grams

x

1 mol

1.01

grams

= 24.752 mol

H

Now we can see from the computation above that every

6.245 mol

C

= 24.752 mol

H

Dividing both sides by the smallest number of moles, (in this case 6.245 mol

C

)

C

=

6.245

mol

6.245

mol

= 1

H

=

24.752

mol

6.245

mol

= 3.98

≈

4

Therefore, empirical formula is

C

1

H

4

or simply,

C

H

4

.