What Is the Molecular Formula of the Hydrocarbon in This Combustion Analysis?

[Ose90]

Homework Statement

6.0 cm^3 of a gaseous hydrocarbon was sparked with 34.5 cm^3 of oxygen. The volume of the gaseous products after cooling to room temperature was 22.5 cm^3. The volume was reduced to 4.5 cm^3 on passing the gases through aqueous potassium hydroxide. What is the molecular formula of hydrocarbon?

Homework Equations

The Attempt at a Solution

CxHy + ( x + y/4 ) O2 ----> x CO2 + Y/2 H2O

Is this equation correct?Do I miss out any product?

my doubts : First, I try calculating the volume of CO2 produced and It is 18cm^3 and the volume of H2O is apparently 4.5 cm^3. What should I do next?
How to find the volume of oxygen gas that has reacted? Should I convert them into moles by dividing the volume of room temperature? I'm confused :(

 

[chemisttree]

First, I try calculating the volume of CO2 produced and It is 18 cm³ and the volume of H₂O is apparently 4.5 cm³. What should I do next?
How to find the volume of oxygen gas that has reacted? Should I convert them into moles by dividing the volume of room temperature? I'm confused :(

You have found the volume of CO₂. Convert it to moles to determine 'x'. What remains is water vapor. Find the number of moles of that and determine 'y'.

 

[Blueshift5]

Based on the given information, the equation you have written appears to be correct. To find the molecular formula of the hydrocarbon, you will need to calculate the moles of each product (CO2 and H2O) using the ideal gas law (PV = nRT) and then use the mole ratio to determine the number of moles of carbon and hydrogen in the hydrocarbon. From there, you can use the molar masses of carbon and hydrogen to determine the molecular formula.

To find the volume of oxygen gas that reacted, you will need to use the initial volume of oxygen (34.5 cm^3) and the volume of the products (22.5 cm^3). The difference between these two volumes will give you the volume of oxygen that reacted.

I hope this helps. If you are still unsure, I recommend consulting with your teacher or a classmate for further clarification. Good luck!