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Topic: Distinguishing qualitatively HCl and CH3COOH  (Read 7754 times)

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Offline zeoblade

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Distinguishing qualitatively HCl and CH3COOH
« on: March 01, 2010, 09:26:31 PM »
I'm trying to think of a qualitative test to distinguish between HCl and CH3COOH and I can come up with nothing other than the reaction rate.

For example:

HCl(aq) + Zn(s) --> ZnCl2(aq) + H2(g)
The reaction will happen very fast relative to:

CH3COOH(aq) + Zn(s) --> Zn(O2CCH3)2(aq) + H2(g)

Is there a better way to distinguish qualitatively? I'm so tempted to use a pH metre but the purpose is qualitative, not quantitative

Offline zeoblade

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Re: Distinguishing qualitatively HCl and CH3COOH
« Reply #1 on: March 01, 2010, 09:34:49 PM »
I was also thinking of using AgNO3(s) so that with HCl(aq) --> HNO3(aq) + AgCl2(s) forms that can be heated to produce Ag(s) and Cl2(g)

However, AgNO3(s) + CH3COOH(aq) --> HNO3(aq) + AgO2CCH3(s) forms that won't give off the yellow-green coloured Cl2(g)

Is this fair to state?

Also would the acetate decompose to CO2(g) + H2O(l)?

Offline Borek

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Re: Distinguishing qualitatively HCl and CH3COOH
« Reply #2 on: March 02, 2010, 03:04:45 AM »
Silver idea is not a bad one - what do you know about solubility of siver chloride and silver acetate? What should you observe adding AgNO3 to both acids?

Note: silver chloride is NOT AgCl2.
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Offline 408

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Re: Distinguishing qualitatively HCl and CH3COOH
« Reply #3 on: March 02, 2010, 03:20:46 AM »
Smell.  ( I am serious)

Offline Borek

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Re: Distinguishing qualitatively HCl and CH3COOH
« Reply #4 on: March 02, 2010, 03:21:49 AM »
Deadly serious  ;D
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Offline zeoblade

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Re: Distinguishing qualitatively HCl and CH3COOH
« Reply #5 on: March 02, 2010, 04:40:06 AM »
Thanks guys,

I have been mainly targeting solubility to get a precipitate on one but not the other since the cation really influences the colour of the solution. But it seems to be a tedious process of blindly choosing complementary ions and checking their solubility. Isn't there some easier way of dichotomously coming to the appropriate ion?

I'm not allowed to use any instrumental techniques such as ion chromatography, just simple qualitative tests involving the use of cations or anions. I instantly thought of odour and pH but I've been restricted to manipulation of ions.

It mainly seems you have to be creative and pluck an ion out of thin air from a VAST knowledge of product solubility, colour, stability. Is there some logical rationale I could use?

Offline 408

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Re: Distinguishing qualitatively HCl and CH3COOH
« Reply #6 on: March 02, 2010, 12:13:39 PM »
Knowing solubility tables far too well.  Use lead nitrate or silver nitrate as said above.  Seeing as you cannot go the easy route of smelling them.

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