Question

A sample of C25H52 weighs 29.29 g. Its molar mass is 352.77g/mol. How many grams of carbon are in this sample?

Any help is much appreciated!

Answer 1

`24.93g`, rounded to two decimal places.

Explanation:

Given is sample of `"C"_25"H"_52`

We see that `1" g mol"` of sample has `25` carbon atoms

Taking Average atomic mass of carbon `"C"=12.011" amu"`, we obtain gram molecular weight of carbon in 1 mol of sample`=25xx12.011`
`=300.275`
Setting up the equation

`352.77g` of sample has carbon`=300.275g`
`1g` of sample has carbon`=300.275/352.77g`
`29.29 g` of sample has carbon`=300.275/352.77xx29.29`
`=24.93g`, rounded to two decimal places.

Answer 2

Approx. `25*g`

Explanation:

`%"by mass of carbon with respect to 1 mole of "C_25H_52` `=` `(25xx12.011*g*mol^-1)/(352.77*g*mol^-1)xx100%=85.12%`

And thus, in a `29.29*g` mass, `%C=29.29*gxx85.12%=??`