Question

How many moles of carbon, hydrogen, and oxygen are present in a 100-g sample of ascorbic acid?

Answer 1

There are:

3.41 moles of C

4.54 moles of H

3.40 moles of O.

Why?

To solve the problem, the first thing that we need to do is to write the chemical formula of the ascorbic acid.

`C_(6)H_(8)O_(6)`

Now, we know that there are 100 grams of the compound, so, the masses of each element will represent the percent in the compound.

We have that:

`C_(6)=12.0107g*6=72.08g\\\\H_(8)=1.008g*8=8.064g\\\\O_(6)=15.999g*6=95.994g\\\\C_(6)H_(8)O_(6)=72.08g+8.064g+95.994g=176.138g`

To know the percent of each element, we need to to the following:

`C=(72.08g)/(176.138g)*100=0.409*100=40.92(percent)\\\\H=(8.064g)/(176.138g)*100=4.58(percent)\\\\O=(95.994)/(176.138g)*100=54.49(percent)`

So, we know that for the 100 grams of the compound, there are:

40.92 grams of C

4.58 grams of H

54.49 grams of O

We know the molecular masses of each element:

`C=12.0107(g)/(mol)\\\\H=1.008(g)/(mol)\\\\O=15.999(g)/(mol){mol}`

Now, to calculate the number of moles of each element, we need to divide the mass of each element by the molecular mass of each element:

`C=(40.92g)/(12.010(g)/(mol))=3.41mol\\\\H=(4.58g)/(1.008(g)/(mol))=4.54mol\\\\O=(54.49g)/(15.999(g)/(mol))=3.40mol`

Hence, we have that there are 3.41 moles of C, 4.54 moles of H, and 3.40 moles of O.

Have a nice day!