Sulfuric Acid Color
Date: June 2008
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?
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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Update: June 2012