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Topic: regarding question..  (Read 4064 times)

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Offline firzzy87

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regarding question..
« on: July 18, 2007, 08:54:34 AM »
Why does benzoic acid precepitate out when the aqueous layer is acidified with HCl??

and

is it ok to leave a bottle of anydrous sodium sulfate or calcium chloride open??
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Offline macman104

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Re: regarding question..
« Reply #1 on: July 18, 2007, 09:00:17 AM »
Benzoic Acid precipitates, because it forms an insoluble salt with HCl.

EDIT:  Apologies for the incorrect information for the first part.  I never liked solubility separations.

No, they are anhydrous for a reason.  Don't leave them open.
« Last Edit: July 18, 2007, 09:31:25 AM by macman104 »
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Offline firzzy87

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Re: regarding question..
« Reply #2 on: July 18, 2007, 09:05:43 AM »
i can't understand your 2nd answer , anyhydrous means no water .. so if we leave it, is it will contributed to an explosion...
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Offline macman104

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Re: regarding question..
« Reply #3 on: July 18, 2007, 09:16:01 AM »
Correct, it does mean without water, if you leave it open for extended periods of time, it will slowly absorb water, and wreck the compound.
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Offline vladi307

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Re: regarding question..
« Reply #4 on: July 18, 2007, 09:23:47 AM »
benzoate acid is insoluble in water. Sodium Benzoate is soluble and if a solution of this salt acidified with HCl we have the reaction:

PhCOONa + HCl= PhCOOH + NaCl

Sodium sulfate and calcium chloride are hygroscopic salts and very useful to remove water from a substance or a solution. They absorb moisture from the atmosphere and you must don't leave them open.
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