Q.
n-butane is produced by monobromination of ethane
followed by Wurtz's reaction. Calculate volume of ethane at
NTP required to produce 55gn-butane, if the bromination
takes place with 90% yield and the Wurtz's reaction with
85% yield.
Reactions involved are C2H6+Br2→C2H5Br+HBr 2C2H5Br+2Na→C4H10+2NaBr
Actual yield of C4H10=55g which is 85% of theoretical yield. ⇒ Theoretical yield of C4H10=8555×100=64.70g
Also, 2 moles (218g)C2H5Br gives 58g of butane. ⇒64.70g of butane would be obtained from 582×64.70=2.23 mole C2H5Br
Also yield of bromination reaction is only 90%, in order to have
2.23 moles of C2H5Br , theoretically 902.23×100=2.48 moles of C2H5Br required.
Therefore, moles of C2H6 required =2.48 ⇒ Volume of C2H6(NTP) required =2.48×22.4=55.55L.