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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: meenu on January 14, 2009, 07:32:52 AM

Title: unknown compound
Post by: meenu on January 14, 2009, 07:32:52 AM: When compound A is treated with HNO3 , no gas is evolved but the solution has yellow colour. Identift the compound.

1 - NaCL 2- KI 3- Na2CO3 4- Na2HPO4 5 - Na2SO4 6 - not any of above

I know
NaCL + HNO3 -------> NaNO3 aq + HCL gas
KI + HNO3 -----> KNO3 aq + HI
this option is possible but question say ' no gas is evolved ' so how the solution turns yellow. does HI give the yellow color to solution ?
Na2CO3 + 2HNO3 ----> NaNO3 aq + H2O (l) + CO2 gas
Na2HPO4 + HNO3------> NaNO3 aq + H3PO4 aq
i dont know color of resulting solution
Na2SO4 + HNO3 ------->NaNO3 aq + H2SO4 aq
again i dont know color of solution
:(
or the answer is not any of above mentioned compounds
Title: Re: unknown compound
Post by: Arkcon on January 14, 2009, 08:15:30 AM: OK, try to look at the products, if they're the same every time (most of the time,) and you're looking for a yellow color, would this reaction work to differentiate them? Afterward, you will have to look up some of these compounds, to see what color they give in solution.
Title: Re: unknown compound
Post by: AWK on January 14, 2009, 09:33:26 AM: HI is a strong reductor, HNO3 is an oxidizer
Title: Re: unknown compound
Post by: firedamage on January 15, 2009, 10:35:24 AM: HNO3 act as an oxidizer?what is an oxidizer?
Title: Re: unknown compound
Post by: Adamcp898 on January 15, 2009, 10:44:39 AM: Quote from: firedamage on January 15, 2009, 10:35:24 AM
HNO3 act as an oxidizer?what is an oxidizer?

An oxidizer or oxidzing agent is the chemical that is reduced in a redox reaction, i.e. it gains electrons
Title: Re: unknown compound
Post by: firedamage on January 16, 2009, 06:10:45 AM: Na2HPO4 + HNO3------> NaNO3 aq + H3PO4 aq(colourless solution)

Na2SO4 + HNO3 ------->NaNO3 aq + H2SO4 aq(colouless solution)