Question

When a sample of cyclohexEne is burned in oxygen, 4.822 g of CO2 and 1.650 g of H2O are obtained. What is the simplest formula for cyclohexene?

Answer 1

The empirical formula of cyclohexene is C₃H₅

Step-by-step explanation:

Given parameters:

Mass of CO₂ produced = 4.822g

Mass of H₂O produced = 1.650g

Unknown:

Simplest formula of cyclohexene or empirical formula of cyclohexene = ?

Solution:

We first write the balanced combustion equation of the cyclohexene in oxygen gas:

Cyclohexene = C₆H₁₀

2C₆H₁₀ + 17O₂ →12CO₂ + 10H₂O

From the gases produced, we can obtain the masses of the constituent atoms that makes up cyclohexene. Cyclohexene which is a hydrocarbon is made up of hydrogen and carbon atoms:

Mass of C in CO₂ =
`(molar mass of C)/(molar mass of CO_(2) )` x mass of CO₂

Mass of C =
`(12)/(44)` x 4.822 = 1.3151g

Mass of H in H₂O =
`(molar mass of H)/(molar mass of H_(2)O )` x mass of H₂O

Mass of H =
`(2)/(18)` x 1.650 = 0.1833g

Using these masses, we can find the empirical formula of the hydrocarbon:

C H

Masses(g) 1.3151 0.1833

Number

of moles
`(1.3151)/(12)`
`(0.1833)/(1)`

0.1096 0.1833

Simplest

form
`(0.1096)/(0.1096)`
`(0.1833)/(0.1096)`

1 1.672

Empirical formula is usually expressed to the simplest whole number ratios. Therefore, to obtain the simplest whole number ratio here, simply multiply by a factor of 3:

1 x 3 1.672 x 3

3 5

The empirical formula of cyclohexene is C₃H₅