The combusion of 20.63 mg of compound Y whichcontain only C,H and O with excess oxygen gave 57.94 mg of CO2 and11.85 mg of H2O. calculat how many mg of C,H and O is present inthe original sample Y Carbon _____________________ mg C Hydrogen__________________mg H Oxygen_______________mg O The combusion of 20.63 mg of compound Y whichcontain only C,H and O with excess oxygen gave 57.94 mg of CO2 and11.85 mg of H2O. calculat how many mg of C,H and O is present inthe original sample Y Carbon _____________________ mg C Hydrogen__________________mg H Oxygen_______________mg O Hydrogen__________________mg H Oxygen_______________mg O
Explanation / Answer
The unknown compound contains only C, H and O and CO2and H2O are the only products. So all the carbon in the original compound is in CO2. 57.94 mg of CO2. % of C in CO2 = ( Atomic mass of C / Molar mass of CO2) *100 = ( 12 g/mol / 44 g/mol ) *100 =27.27 % So Mass of C in 57.94 mg of CO2 = (27.27 / 100 ) * 57.94mg =15.8 mg All the Hydrogen in the unknown compound is present inH2O. % of H in H2O = ( 1.008 g / 18 g/mol ) * 100 =5.6 % % of H in 11.85 mg of H2O = (5.6 / 100 ) * 11.85 mg =0.6636 mg So combined mass of H and C = 15.8 + 0.6636 = 16.46 mg So the remaining mass is oxygen = 20.63 mg - 16.46 mg = 4.17mg So Carbon - 15.8 mg Hydrogen - 0.6636 mg Oxygen - 4.17 mg