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Topic: Color of sulfuric acid?  (Read 30801 times)

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Halma

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Color of sulfuric acid?
« on: December 24, 2005, 01:20:55 PM »

First of all, Merry Christmas everybody!

Just a quick question:  What color is pure sulfuric acid?  Wikipedia tells me it's clear and colorless, but maybe that's just an approximation?

I got some from a hardware store, and it's an oily brown color.  It's concentrated enough that it doesn't eat metal very much unless you add water.

But got some "battery acid" today, and it's pretty clear, but not nearly as concentrated.  (It doesn't even boil the water you add it to.)

So is the hardware store stuff impure, or is the battery acid version too dilute to show the color?

BTW, what is the scooby snack thing?  Is it one of those reputation systems, where I give a snack to somebody who helps me?

Offline Bakegaku

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Re:Color of sulfuric acid?
« Reply #1 on: December 24, 2005, 01:35:23 PM »
I think that pure sulphuric acid is colourless, but common impurities may make it a yellow or brownish colour.  

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Offline jdurg

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Re:Color of sulfuric acid?
« Reply #2 on: December 25, 2005, 12:33:25 AM »
Yes, pure sulfuric acid should be a completely colorless, oily liquid.  As has been mentioned already, numerous contaminants can make it seem yellowish or brownish.  Especially if those contaminants are organic in nature.

I also noticed in your post that you talked about adding water to an acid.  PLEASE don't do that.  ALWAYS add a concentrated acid to water and not the reverse.  Many people underestimate the amount of heat generated when a concentrated acid is diluted, and if you're not careful you may wind up with a face full of concentrated acid.  (As the water instantly boils and sprays the acid up in a steam explosion).  Even if you're confident in what you're doing, it's always best to make it a habit to add the concentrated to the dilute.   ;D
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Chrataxe

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Re:Color of sulfuric acid?
« Reply #3 on: December 26, 2005, 05:30:33 AM »
Definitely clear.  We used some 97% sulfuric acid in lab and it was clear.  Also, "concentrated" is a vague term.  I was looking at some HCl at the hardware store the other day and it was only like 60% or so...don't remember off the top of my head.

Offline Borek

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Re:Color of sulfuric acid?
« Reply #4 on: December 26, 2005, 06:40:42 AM »
Also, "concentrated" is a vague term.  I was looking at some HCl at the hardware store the other day and it was only like 60% or so...don't remember off the top of my head.

In case of sulfuric acid "concentrated" means usually about 96-98%, as that's how it is sold.

HCl you have seen was not 60%, as HCl can't be made more concentrated than about 40%.
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Halma

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Re:Color of sulfuric acid?
« Reply #5 on: December 27, 2005, 03:42:06 PM »

Thanks for the replies!

Also, jdurg, no, I don't add water to acid!  I know I said "add water", but I meant mix with water, not as in adding water literally.

If I may ask, where might I find the FAQ?  All I found was the forum rules.

Offline Bakegaku

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Re:Color of sulfuric acid?
« Reply #6 on: December 28, 2005, 05:13:10 PM »
Quote
If I may ask, where might I find the FAQ?  All I found was the forum rules.

Oh, sorry. I forgot, they're under "help."  The link to help is on the green bar underneath the Chemical Forums logo.
"True knowledge exists in knowing that you know nothing"
-Socrates

"I see, I forget.  I hear, I remember.  I do, I understand"
-Confucius

"Nothing will benefit human health and increase chances for survival of life on Earth as much as the evolution to a vegetarian diet."
- Albert Einstein?

"American cartoons place characters in situations; anime
places situations around characters.  Anime characters
are not like fictional characters but more like fictional
people; their actions stem directly from their personalities,
and not just as a means to move the story's plot
forward.  We are made to sympathize with them, and
not simply be entertained by them."
~John Oppliger~

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