AS level chemistry- help!!

a.f.x.d

A sample of 50 cm3 of ethanol gas is burned completely in 200 cm3 of oxygen.
C2H5OH(g) + 3O2(g) → 2CO2(g) + 3H2O(g)
All volumes are measured at a temperature of 400 K and 1 atm pressure. What is the total volume of gas when the reaction is complete?

A 150 cm3
B 200 cm3
C 250 cm3
D 300 cm3

the answer is D but I don't know how

Reply 1

an150

Original post by a.f.x.d

For ethanol and O2 to react in a 1:3 ratio (as in the equation), 150cm3 of O2 will be used - leaving 50cm3 unreacted because it is in excess.

The products will take up 250 cm3 - (50cm3 of ethanol x 5), but the question asks for the total volume of gas, not just the volume of products, so there will be 300 cm3 in total.

Hope this helps lol

Reply 2

jewelbuster

Original post by an150

For ethanol and O2 to react in a 1:3 ratio (as in the equation), 150cm3 of O2 will be used - leaving 50cm3 unreacted because it is in excess.
The products will take up 250 cm3 - (50cm3 of ethanol x 5), but the question asks for the total volume of gas, not just the volume of products, so there will be 300 cm3 in total.
Hope this helps lol

why does the product take up 250cm3? could u pls elaborate?