Answer:
C₅H₇N
Explanation:
Empirical formula is defined as the simplest positive integer ratio of atoms present in a compound
The reaction of combustion of nicotine, CₐHₓNₙ produce:
CₐHₓNₙ + O₂ → a CO₂ + x/2 H₂O + n NO₂
As you can see, moles of carbon are the same of CO₂, that is:
18.515mg CO₂ ₓ (1mmol / 44mg) = 0.4208mmol Carbon
In mass:
0.4208mmol Carbon ₓ (12mg / 1mmol) = 5.0496mg C
Moles of water are 1/2 moles of hydrogen, that are:
5.308mg H₂O ₓ (1mmol / 18gm) = 0.2959mmol water ₓ (2mol H / 1mol H₂O) =0.5898mmol H
In mass:
0.5898mmol H ₓ (1mg / 1mmol) = 0.5898mg
mg of nitrogen are:
6.825mg - 5.0496 - 0.5898 = 1.1856mg N
Moles are:
1.1856 mg N ₓ (1mmol / 14mg) = 0.0847mmol N
The ratio between moles of nitrogen, hydrogen and carbon are:
C: 0.4208mmol / 0.0847mmol = 5
H: 0.5898mmol / 0.0847mmol = 7
N: 0.0847mmol / 0.0847mmol = 1
That means empirical formula is:
C₅H₇N
I hope it helps!
