Question

Part A A mixture of cyclopropane gas and oxygen is used as an anesthetic Cyclopropane contains 85.7% C and 14.3% H by mass. Al 50.0 C and 0.984 at pressure. 1.56 g cyclopropane has a volume of 1.00 L. What is the molecular formula of cyclopropane? - AED 0 ? Submit Request Answer < Return to Assignment Provide Foedback

Answer 1

Given:
P = 0.984 atm
V = 1.0 L
T = 50.0 oC
= (50.0+273) K
= 323 K

find number of moles using:
P * V = n*R*T
0.984 atm * 1 L = n * 0.08206 atm.L/mol.K * 323 K
n = 3.712*10^-2 mol

mass(solute)= 1.56 g


use:
number of mol = mass / molar mass
3.712*10^-2 mol = (1.56 g)/molar mass
molar mass = 42.02 g/mol

we have mass of each elements as:
C: 85.7 g
H: 14.3 g


Divide by molar mass to get number of moles of each:
C: 85.7/12.01 = 7.136
H: 14.3/1.008 = 14.19


Divide by smallest to get simplest whole number ratio:
C: 7.136/7.136 = 1
H: 14.19/7.136 = 2

So empirical formula is:CH2

Molar mass of CH2,
MM = 1*MM(C) + 2*MM(H)
= 1*12.01 + 2*1.008
= 14.026 g/mol

Now we have:
Molar mass = 42.02 g/mol
Empirical formula mass = 14.026 g/mol
Multiplying factor = molar mass / empirical formula mass
= 42.02/14.026
= 3

So molecular formula is:C3H6
Answer: C3H6