Question

What is the (mass) percent of carbon element in sugar?

Answer 1

Well, we need the product of the quotient...

`"Mass of carbon"/"Molecular mass of compound"xx100%`

Explanation:

And we know, or should know that the molecular mass of sugar is `C_6H_12O_6` (of course this means that the empirical formula is `CH_2O`, from which we could also calculate the `%C` by mass)...

SO...

`%H=(12xx1.00794*g*mol^-1)/(180.16*g*mol^-1)=6.71%`

`%O=(6xx16.00*g*mol^-1)/(180.16*g*mol^-1)=54.28.%`

...and `%C=(6xx12.01*g*mol^-1)/(180.16*g*mol^-1)=40.00%`

Capisce?