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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: CSG on May 10, 2010, 10:57:58 AM

Title: Iodine Numbers
Post by: CSG on May 10, 2010, 10:57:58 AM

Hi,

I understand that the iodine number is the number of moles of iodine reacting with one mole of fat/oil which indicates the number of double bonds present in the fat/oil molecule.

However I am having trouble calculating them.

Can someone show me how to solve the following question please?

0.014 moles of a particular oil was found to react exactly with 14.2g of iodine. Calculate the number of moles of iodine that reacted and state what can be deduced about the structure of the oil from this information.

This is as far as I got:

Number of moles of iodine: 14.2/126.9 = 0.112mol

Title: Re: Iodine Numbers
Post by: MOTOBALL on May 11, 2010, 07:24:24 PM

Your starting point is the definition of the Iodine number

1 mole of Iodine reacts with 1 mole of fat/oil that contains 1 double bond,

then,

0.112 moles of I2 . 0.112 moles fat that contains 1 DB
0.112 moles of I2...0.014 moles fat that contains 0.112/0.014 = 8 DB

You have 8 x >C=C< in your sample.

Title: Re: Iodine Numbers
Post by: Borek on May 12, 2010, 02:56:50 AM

Quote from: CSG on May 10, 2010, 10:57:58 AM

Number of moles of iodine: 14.2/126.9 = 0.112mol

As we have already found somewhere else - it is not 0.112, as iodine is not atomic.

Title: Re: Iodine Numbers
Post by: JGK on May 12, 2010, 02:57:29 PM

This may be of help http://www.kyoto-kem.com/en/pdf/industry/FatVegetableOil/ETIB-99424.pdf (http://www.kyoto-kem.com/en/pdf/industry/FatVegetableOil/ETIB-99424.pdf)

Title: Re: Iodine Numbers
Post by: MOTOBALL on May 12, 2010, 07:44:31 PM

Correction, you have 4 x DB

Mea culpa !!!