An unknown compound contains only carbon, hydrogen, and oxygen combustion of 7.50 of this compound produced 11.0 of carbon dioxide and 4.50 of water.

1) how many moles of carbon, c, were in the original sample?
an unknown compound contains only carbon, hydrogen, and oxygen combustion of 7.50 of this compound produced 11.0 of carbon dioxide and 4.50 of water.

1) how many moles of carbon, c, were in the original sample?

7.50 g of a compound that contains hydrogen, carbon and oxygen, which produces 11.0 g of carbon dioxide and 4.5 g of water when burned, contains 0.25 moles of carbon in the original sample.

That is;

CxHyOn + O2  = CO2 + H2O  

Moles of carbon in the original sample of a Hydrocarbon  

In our case:

Mass of CO2 formed is 11.0 g  

Mass of the hydrocarbon is 7.5 g  

Mass of carbon:  

1 mole of CO2 contains 12.0 g of carbon

44.0 g/mol contains 12.0 g of carbon

Hence; 11.0 g of CO2 will contain;

= (11x 12)/44.0g

= 3 g of carbon  

This means; the original mass of Carbon in 7.5 g of the hydrocarbon is 3 g  

Number of moles = mass/R.A.M

                             = 3 g/ 12.0 g/mol

                             = 0.25 moles  

Hence; 7.5 g of the hydrocarbon contained 0.25 moles of carbon.

Level: High school  

Subject: Chemistry  

Topic: Empirical formula and molecular formula  

geosphere and hydrosphere.

this is because the geosphere has to do with geological events, while the hydrosphere controls all water on earth.