What does "excess" mean when talking about chemistry?

Asked by Les (10005

) August 27th, 2008

I’m giving this a try here. I saw this phrase in a book months ago and for the life of me, can’t find it again. I am doing titrations for iodine, and the phrase is “solutions containing an excess of iodine”. I want to make sure I understand this correctly. I have an idea of what this means, but I was hoping some chemist in the collective may know for sure. Thanks for any help.

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6 Answers

It means that has more iodine than other chemicals in the mixture.

winblowzxp (503

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It means that there’s more iodine in the solution than will react with the other chemicals. IOW, all of the other chemicals react with the iodine until they’re used up… and there’s still iodine left over. Add more of those other chemicals, and the reaction will continue.

robmandu (21331

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@rob and win : Thanks. That is sort of what I was thinking (and rob, your explanation especially makes sense for my project.)
Thanks for the help.

Les (10005

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To add to robmandu’s response, your reaction becomes a limiting reaction when you have components that prevent the procession of your experiment. Also, look into saturation and super-saturation of solutions.

Sloane2024 (1884

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