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Answer part b) only A compound produced as a by-product in an industrial synthesis of...

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lak-86 | Student, Undergraduate | (Level 1) Salutatorian

Posted August 8, 2013 at 9:11 AM via web

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Answer part b) only

A compound produced as a by-product in an industrial synthesis of polymers was found to contain C, H, and I. A combustion analysis of 1.70 g of the compound produced 1.32 g of CO2 and 0.631 g of H20. The mass percentage of I in the compound was determined by converting the I in a 0.850 g sample of the compound into 2.31 g of PbI2.

a) What is the empirical formula of the compound? (This part is already answered in http://www.enotes.com/homework-help/compound-produced-by-product-an-industrial-446756)

b) Could the compound also contain oxygen? Explain your answer.?

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jeew-m | College Teacher | (Level 1) Educator Emeritus

Posted August 8, 2013 at 10:05 AM (Answer #1)

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From the previous part;


we have obtained that the empirical formulae of the compound is `C_3H_7I_2`

When we burn the compound with oxygen, Iodine has no effect on the reaction.

From mass balance in combustion;

Amount of `O_2` required for reaction `= (1.32+0.631)-1.7 = 0.251g`

Amount of `O_2` required for reaction `= 0.251/32 = 0.0078mol`

Amount of `H_2O` moles obtained `= 0.035`

Mole ratio

`H_2O:O_2 = 0.035:0.0078 = 9:2`

From mass balance the ratio of `O_2:H_2O=2:9` .

Let us assume that there is no oxygen in the compound. Then all the oxygen in `CO_2` and `H_2O` will be provided by `O_2` gas only.

But the results from the mass balance says that we have more O in `H_2O` than `O_2` gas. This means there should be another source that supplies O moles to the combustion reaction. So that would be the compound it self.This means the compound has contained Oxygen.

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