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Name: Sebastian
Status: student
Grade: 9-12
Date: June 2008


Question:
Why is it that some sulfuric acid is gold, while other sulfuric acid is colorless? My chemistry teacher said it is because of the age. Is gold sulfuric acid any different than colorless - like is one more potent than the other?



Replies:
Sebastian,

The first thing you have to consider is that, especially with clear liquids, a drop of something that gives color can have a strong effect on the final color of the liquid. You can put just a drop of ink in water and no amount of additional water can ever change that sample to colorless again. Our eyes are very sensitive to distinguishing colored solutions from colorless solutions.

Keeping that in mind, anything that could have contaminated the sulfuric acid, some oxidized substances, if the solution touched rubber (as the rubber stopper or the bulb of a medicine dropper), some oil or grease (maybe from the stopper), something leached from the bottle cover - anything can cause discoloration. Yellow or tan is about the most common color for organic substances.

So, the strength of the sulfuric acid is probably not affected. The bottle just contains some impurities.

Greg (Roberto Gregorius)



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