Can someone check this answer?

Moderators: Chem_Mod, Chem_Admin

Julia Mazzucato 4D
Posts: 64
Joined: Fri Aug 30, 2019 12:17 am

Can someone check this answer?

Postby Julia Mazzucato 4D » Sun Nov 17, 2019 6:05 pm

Doing a problem from a Test Bank exam, and I just wanted to check my answer.

A 2.00 g sample of a compound containing only C, H, and O undergoes complete combustion and gives off 4.86g CO2 and 2.03g H2O. What is the empirical formula of the substance?

My answer was C2H4O5 but i just wanted to check?

Jiyoon_Hwang_2I
Posts: 101
Joined: Sat Sep 14, 2019 12:17 am

Re: Can someone check this answer?

Postby Jiyoon_Hwang_2I » Sun Nov 17, 2019 6:33 pm

I actually got C4H8O.

First, I used the grams of CO2 given to determine the grams of carbon. Next, I used the grams of H2O to determine the grams of hydrogen. Then, add these values together and subtract from 2.00 g of the sample compound to determine how many grams of oxygen there are. Afterwards, convert the grams of carbon, hydrogen, and oxygen into moles. Then, divide each value by the smallest number of moles that was calculated (in this case, oxygen has the smallest number of moles so divide the moles of carbon, hydrogen, and oxygen by this value). Then, you should get 4 moles of carbon, 8 moles of hydrogen, and 1 mole of oxygen which means the empirical formula is C4H8O.

Julia Mazzucato 4D
Posts: 64
Joined: Fri Aug 30, 2019 12:17 am

Re: Can someone check this answer?

Postby Julia Mazzucato 4D » Sun Nov 17, 2019 8:25 pm

Jiyoon_Hwang_4D wrote:I actually got C4H8O.

First, I used the grams of CO2 given to determine the grams of carbon. Next, I used the grams of H2O to determine the grams of hydrogen. Then, add these values together and subtract from 2.00 g of the sample compound to determine how many grams of oxygen there are. Afterwards, convert the grams of carbon, hydrogen, and oxygen into moles. Then, divide each value by the smallest number of moles that was calculated (in this case, oxygen has the smallest number of moles so divide the moles of carbon, hydrogen, and oxygen by this value). Then, you should get 4 moles of carbon, 8 moles of hydrogen, and 1 mole of oxygen which means the empirical formula is C4H8O.


Ok just redid the problem and I messed up my calculations early on. Just got your answer. Thank you!


Return to “Empirical & Molecular Formulas”

Who is online

Users browsing this forum: No registered users and 2 guests