color of HCL

[jordehwa]

i bought some 31%hydrochloric acid from the home depot for the first time and i notice its has a tiny bit of greenish color to it is this normal?

[JGK]

Wikipedia describes HCL as "Clear, colorless to light-yellow liquid"

 

So a yellow/green colour wouldn't be unexpected.

[Justonium]

Try neutralizing it with a colorless base such as sodium sodium bicarbonate, sodium carbonate, or sodium hydroxide, and if the color remains, you know it is caused by impurities. If the color goes away, the test is inconclusive, though. Strange, I've never heard of hydrochloric acid having a color in high concentrations; I've used 12 molar before in small amounts, and I didn't notice any coloring, but maybe you can see it through a thicker cross section of the liquid, though I'd still be skeptical that hydrochloric acid would actually look green. I suspect that the green color is caused by contamination with ferrous ions. I don't see how pure hydrochloric acid could possibly look green, because neither hydronium ions nor chloride ions are green.

[UC]

Industrial HCl often has impurities in it. Pure material is completely colorless.

[jordehwa]

Should i purify it? my method of purification would turn 31% HCL in to 15% reagent grade, witch is good but will only 15% work for making chlorides from metal? like zinc, tin and aluminum?

[Fuzzwood]

For zinc? Sure, but I am not sure for the other metals. I know they should theoretically by wise of standard electrode potentials. But I am not sure if the acid is able to eat through the oxide layers of the other 2 metals.

[jordehwa]

do you think i can get away with using the impure HCL? because it takes me two weeks to purify only 100 ml of HCL.

[Fuzzwood]

Impurities can sometimes be organic stuffs, but can also be iron salts. Can't you simply distill it? It will also get rid of colorless impurities.

[jordehwa]

yeah i will do that. thanks guys

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hey guys 1 more question how much baking soda to neutralize 100 ml of 15% HCL.

 

thanks

[jordehwa]

Good news i opened the bottle to get a better look and its not green at all there is no color its super clear and works great. i got 2 galons of it for 10 bucks.

 

it must have ben the bottle that was sorry guys but thanks for answering anyway.

[Justonium]

yeah i will do that. thanks guys

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Merged post follows:

Consecutive posts merged

hey guys 1 more question how much baking soda to neutralize 100 ml of 15% HCL.

 

thanks

 

Calculate the molarity, (i believe its around 6M), and then you know that there will be 1/10th that many moles of HCL in 100mL (so about 0.6 moles). You need the same molarity of baking soda to neutralize it, so just multiply the moles by its molar mass (which is about 84g/mole), to get the grams of baking soda required. To make the solution safe to handle, add a little excess baking soda just in case, to get rid of any remaining acid.

[Arthur Dent]

Maybe there are some nickel impurities in your HCl... If I recall, nickel chloride is a yellowish-green salt.

 

The RONA brand HCL I buy at the hardware store in my area is perfectly clear, 20BÉ , and comes in a tightly sealed plastic bottle in a polythene bag.

 

EDIT: mmh. just saw you posting saying the HCl was clear afterall. Maybe it was a reflection from the label or something...

Edited April 3, 2010 by Arthur Dent