Acid + Base > Salt (solid or aqueous?) + Water

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jo7777
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#1
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#1
I've just been doing a question and im a little confused.
I always assumed that in a neutralisation reaction acid + base makes a salt, and this salt is a solid.
However, I just read that HNO3 (AQ) + Ca(OH)2 (AQ) > Ca(NO3)2 (AQ) + H2O (L)
So are salts always aqueous or can they sometimes be solid?
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lerjj
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#2
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#2
(Original post by jo7777)
I've just been doing a question and im a little confused.
I always assumed that in a neutralisation reaction acid + base makes a salt, and this salt is a solid.
However, I just read that HNO3 (AQ) + Ca(OH)2 (AQ) > Ca(NO3)2 (AQ) + H2O (L)
So are salts always aqueous or can they sometimes be solid?
Depends whether they are soluble or not. Soluble salts will be in solution, insoluble will obv not be. I don't 100% trust your equation because I thought that Calcium Hydroxide was insoluble in water- hence the insoluble white precipitate when mixed with NaOH.

But for a correct (I think) example:
 \text{HCl}_{(aq)} + \text{NaOH}_{(aq)} \rightarrow \text{NaCl}_{(aq)} + \text{H}_2 \text{O}_{(l)}
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jo7777
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#3
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#3
(Original post by lerjj)
Depends whether they are soluble or not. Soluble salts will be in solution, insoluble will obv not be. I don't 100% trust your equation because I thought that Calcium Hydroxide was insoluble in water- hence the insoluble white precipitate when mixed with NaOH.

But for a correct (I think) example:
 \text{HCl}_{(aq)} + \text{NaOH}_{(aq)} \rightarrow \text{NaCl}_{(aq)} + \text{H}_2 \text{O}_{(l)}
So If I'm in an exam, how would I know whether or not it's a solid or aqueous salt? This is for AS chem btw
Is it safe to say I can assume it's aqueous?
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lerjj
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#4
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#4
(Original post by jo7777)
So If I'm in an exam, how would I know whether or not it's a solid or aqueous salt? This is for AS chem btw
I do GCSE, so I'm not expected to know how to work this out. I think there are rules of thumb- most sodium compounds are soluble, most hydroxides are soluble, a decent number of calcium ones are insoluble.

From a physics standpoint, if you were provided with the enthalpy and energy changes then you could work it out I suppose.

You probably just have to learn them, but I'll ask my sister (she does A2 so she ought to be able to help...)
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Borek
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#5
Report 8 years ago
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I don't know what is in which syllabus, but there is a set of rules of thumb, so called "solubility rules" (google them) which help remember which salts are soluble and which are not.
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