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A 0. 271-g sample of an unknown vapor occupies 294 ml at 140°c and 847 mmhg. The empirical formula of the compound is ch2. What is the molecular formula of the compound?.

Respuesta :

Answer:when the molar mass M = mass (g)/ no.of moles (Mol)

∴ moles= 0.271 g / M

By using the gas equation:

PV = n RT

when P is the pressure = 847 mmHg / 760 = 1.11 atm

V is the volume = 0.294 L

n = 0.271 / M

R is constant = 0.0821

T= 140+273 = 413 K

so by substitution:

when n = PV/RT

∴ 0.271/ M = 1.11 atm *0.294 L/ 0.0821 *413

∴ M = 28

when the empirical formula of CH2 = 12+2 = 14

∴ the exact no.of moles = 28/14 = 2

∴the molecular formula = 2(CH2) = C2H4

Explanation:

hope it helps

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