What volume of oxygen at N.T.P is needed to cause the complete combustion of 200 mL of acetylene ? Also calculate the volume of carbon dioxide formed.

Explanation

The chemical equation representing the combustion of acetylene is :
`underset("2 Vol.")(2C_(2)H_(2))+underset("5 Vol.")(5 O_(2))rarr underset("4 Vol.")(4 CO_(2))+2H_(2)O`
Step 1. To calculate the volume of `O_(2)` at STP required to after complete combustion of `200 cm^(3)` of acetylene.
Applying Gay Lussac's Law of gaseous volumes,
2 Vol. of `C_(2)H_(2)` required `O_(2)` for complete combustion = 5 Vol.
`therefore 200 cm^(3)` of `C_(2)H_(5)` will require `O_(2)` for complete combustion `=(5)/(2)xx200=500 cm^(3)` at STP.
Thus, the volume of `O_(2)` required at STP.
Step 2. To calculate the volume of `CO_(2)` produced at STP.
Applying Gay Lussac's Law og faseous volumes, 2 Vol. of `C_(2)H_(2)` produce `CO_(2)=4` Vol.
`therefore 200 cm^(3)` of `C_(2)H_(2)` at STP will produce `CO_(2)=(4)/(2)xx200=400 cm^(3)` at STP
Thus, the volume of `CO_(2)` produced `= 400 cm^(3)` at STP.