ENTRANCE EXPERT

ISOMERISM TRICK For ALDEHYDE AND KETONES REMEMBER THIS TABLE FIRST Carbon Number No. of Isomers 1 1 2 1 3 2 4 4 5 8  ALDEHYDES AND KETONES If carbon and hydrogen are in this relation C nH 2n O then be sure the given molecular formula gives ALDEHYDE and KETONE isomers. We know general formula for aldehyde is R-CHO and that of ether is R-CO-R [Since aldehydes and ketones are functional isomers  so from the provided molecular formula both the isomers of aldehydes and ketones can be obtained.] First you should place the provided molecular formula in the above format. Eg. a)  CH 2 O H- CHO [You should omit the carbon of functional group]  no carbon atoms, so total no. of aldehyde isomer =1. To form ketone minimun 3 carbon atoms are required Total isomer = 1 aldehyde isomer only. b)  C 2 H 4 O CH 3 -CHO [Don't count the carbon atom of functional group] Carbon no. 1  so, 1 aldehyde isomer Total ...

ISOMERISM TRICK For Alchols and Ethers REMEMBER THIS TABLE FIRST Carbon Number No. of Isomers 1 1 2 1 3 2 4 4 5 8  ALCOHOLS AND ETHERS If carbon and hydrogen are in this relation C nH 2n+2 O then be sure the given molecular formula gives alcohol and ether isomers. We know general formula for alcohol is R-OH and that of ether is R-O-R [Since alchols and ethers are functional isomers  so from the provided molecular formula both the isomers of alchols and ethers can be obtained.] First you should place the provided molecular formula in the above format. Eg. a)  CH 4 O CH 3 -OH  Here there is only one carbon so from above table it is clear that this formula contains only one alcohol isomer.  To be ether two carbon must be present but there is only one carbon so no ether isomer exists. b)  C 2 H 6 O C 2 H 5 -OH   Carbon no. 2  so, 1 alcohol isomer Now, for ether CH 3 -O-CH 3 Rem: See the car...

 ALKANES Total no. of isomers of alkane can be calculated by this formula : Carbon Number No. of Isomers Upto Heptane 2 n-4 + 1 Octane 2 n-4 + 2 Nonane 2 n-4 + 3 Where n is the no. of  Carbon atoms Eg: C 7 H 16 n = 7 Total no. of alkane isomers: 2 7-4 + 1= 2 3 + 1 = 8+1 = 9 If the carbon and hydrogen atoms are in this format C n H 2n+2  then remember the provided molecular formula gives the isomers of alkane.