The characteristic odor of pineapple is due to ethyl butyrate a compound of 1.95mg ethyl butyrate produces 4.42mg of CO2 and 1.81mg of H2O what is the empirical formula of the compound?

Answer 1

this is the most helpful answer i found online when doing this problem...









a) A characteristic odor of pineapple

first lets find the mass of carbon & hydrogen, using molar masses:
6.3mg CO2 @ 12 mg C / 44mg CO2 = 1.72 mg Carbon
2.58 mg H2O @ 2.02mg H / 18.02mg H2O = 0.29 mg Hydrogen

now lets find mg of oxygen:
2.78mg total - 1.72mg Carbon - 0.29 mg Hydrogen = 0.77mg Oxygen

now let's find mmoles:
1.72mg Carbon @ 1mmol/ 12mg = 0.143mmol C
0.29 mg Hydrogen @ 1mmol/1mg = 0.29mmol H
0.77mg Oxygen @ 1mmol / 16mg = 0.048mmol O

dividing by the smallest to get a ratio of moles;
0.143mmol C / 0.048mmol = 3.0 moles Carbon
0.29mmol H / 0.048mmol = 6.0 moles Hydrogen
0.048mmol O / 0.048mmol = 1 mole oxygen

your first answer : C3H6O
===================================

b)Nicotine

first lets find the mass of carbon & hydrogen, using molar masses:
14.242mg CO2 @ 12 mg C / 44mg CO2 = 3.884 mg Carbon
4.083 mg H2O @ 2.02mg H / 18.02mg H2O = 0.458 mg Hydrogen

now lets find mg of nitrogen:
5.250 mg total - 3.884 mg Carbon - 0.458 mg Hydrogen = 0.908mg nitrogen

now let's find mmoles:
3.884 mg Carbon @ 1mmol/ 12mg = 0.324 mmol C
0.458 mg Hydrogen @ 1mmol/1.01mg = 0.453mmol H
0.908 mg nitrogen @ 1mmol / 14mg = 0.0648 mmol N

dividing by the smallest to get a ratio of moles;
0.324 mmol C / 0.065mmol = 5 moles Carbon
0.453 mmol H / 0.065mmol = 7 moles Hydrogen
0.065 mmol O / 0.065mmol = 1 mole nitrogen

next answer: impirical formula: C5H7N1
=========================

the formula C5H7N1 has
5C's @ 12 ea = 60
7 H's @ 1 ea = 7
1 n @ 14 = 14
the mass totals 81

so If the substance has a molar mass of 160+/- 5g,
then the molecular formula has twice the atoms...

your last answer : molecular formula = C10H14N2