Acidic, basic and neutral salts

jackc91 · 30 Oct 2009, 11:46 AM

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Why are some salts acidic, basic and neutral?

I know that salt formed from strong acid + strong base = neutral etc.

but why?

annabackwards · 30 Oct 2009, 11:57 AM

It's because they react further with water.

Example one - the neutral salt NaCl
It is neutral because the salt does not further react of water in solution.
Na+ + H20 --> Na+ + H20
Cl- + H20 --> Cl- + H20 ---> No Hydronium/Hydroxide ions produced, therefore neutral

Example two - the basic salt NaCH3COO or CH3COONa (doesn't matter which way you write it)
Na+ + H20 --> Na+ + H20
CH3COO- + H20 --> CH3COOH + OH- ---> Hydroxide ions produced, therefore basic

Example three - the acidic salt NH4Cl
NH4+ + H20 --> NH3 + H30+
Cl- + H20 --> Cl- + H20 ---> Hydronium ions produced, therefore acidic

kaz1 · 30 Oct 2009, 12:03 PM

Quote:

Originally Posted by annabackwards

It's because they react further with water.

Example one - the neutral salt NaCl
It is neutral because the salt does not further react of water in solution.
Na+ + H20 --> Na+ + H20
Cl- + H20 --> Cl- + H20 ---> No Hydronium/Hydroxide ions produced, therefore neutral

Example two - the basic salt NaCH3COO or CH3COONa (doesn't matter which way you write it)
Na+ + H20 --> Na+ + H20
CH3COO- + H20 --> CH3COOH + OH- ---> Hydroxide ions produced, therefore basic

Example three - the acidic salt NH4Cl
NH4+ + H20 --> NH3 + H30+
Cl- + H20 --> Cl- + H20 ---> Hydronium ions produced, therefore *acidic

*fixed.

annabackwards · 30 Oct 2009, 12:05 PM

Quote:

Originally Posted by kaz1

*fixed.

Hehe, thanks for the pick up

Just wondering, anyone know of any other acidic salts?

Aerath · 30 Oct 2009, 12:24 PM

Ammonium nitrate methinks.

annabackwards · 30 Oct 2009, 12:53 PM

Quote:

Originally Posted by Aerath

Ammonium nitrate methinks.

Thanks

jackc91 · 30 Oct 2009, 1:30 PM

Quote:

Originally Posted by annabackwards

It's because they react further with water.

Example one - the neutral salt NaCl
It is neutral because the salt does not further react of water in solution.
Na+ + H20 --> Na+ + H20
Cl- + H20 --> Cl- + H20 ---> No Hydronium/Hydroxide ions produced, therefore neutral

Example two - the basic salt NaCH3COO or CH3COONa (doesn't matter which way you write it)
Na+ + H20 --> Na+ + H20
CH3COO- + H20 --> CH3COOH + OH- ---> Hydroxide ions produced, therefore basic

Example three - the acidic salt NH4Cl
NH4+ + H20 --> NH3 + H30+
Cl- + H20 --> Cl- + H20 ---> Hydronium ions produced, therefore acidic

Thanks. Understand now. Much appreciated.

harry4 · 30 Oct 2009, 1:35 PM

ohhhh i thought always thought it was just because it was a strong acid and weak base the resulting salt would be weakly acidic, had no idea about the water

thanks

harry4 · 31 Oct 2009, 7:42 PM

Quote:

Originally Posted by annabackwards

It's because they react further with water.

Example one - the neutral salt NaCl
It is neutral because the salt does not further react of water in solution.
Na+ + H20 --> Na+ + H20
Cl- + H20 --> Cl- + H20 ---> No Hydronium/Hydroxide ions produced, therefore neutral

Example two - the basic salt NaCH3COO or CH3COONa (doesn't matter which way you write it)
Na+ + H20 --> Na+ + H20
CH3COO- + H20 --> CH3COOH + OH- ---> Hydroxide ions produced, therefore basic

Example three - the acidic salt NH4Cl
NH4+ + H20 --> NH3 + H30+
Cl- + H20 --> Cl- + H20 ---> Hydronium ions produced, therefore acidic

i'm a bit confused. isn't CH3COOH acetic acid so it would be acidic

oh i just realised is it because u have Na+ and OH- which is a strong base so strong base plus weak acid gives weak base

annabackwards · 31 Oct 2009, 8:07 PM

Quote:

Originally Posted by harry4

i'm a bit confused. isn't CH3COOH acetic acid so it would be acidic

oh i just realised is it because u have Na+ and OH- which is a strong base so strong base plus weak acid gives weak base

Acetic acid is indeed a weak acid, but its degree of ionisation is extremely low (< 2%), so low that the hydroxide ions produced still make the solution much more basic than the small concentration of hydronium ions produced by the acetic acid would make it acidic. Therefore it's still acidic.

Your reasoning is the basic idea, but if asked the question you would have to say that the salt further reacts with water and give an equation as i did or you won't get full marks

30 Oct 2009, 11:46 AM	#1 (permalink)
jackc91 rumpleshit HSC: 2009 Gender: Male Join Date: Feb 2008 Posts: 103 Last Activity: 20 Nov 2009, 11:17 PM	Acidic, basic and neutral salts You can hide this advertisement by registering. Why are some salts acidic, basic and neutral? I know that salt formed from strong acid + strong base = neutral etc. but why?

30 Oct 2009, 11:57 AM	#2 (permalink)
annabackwards <3 Prophet 9 AyyyTAR Hater HSC: 2009 Gender: Female Location: Sydney Join Date: Jun 2008 Posts: 3,279 Last Activity: Yesterday, 2:25 PM	Re: Acidic, basic and neutral salts It's because they react further with water. Example one - the neutral salt NaCl It is neutral because the salt does not further react of water in solution. Na+ + H20 --> Na+ + H20 Cl- + H20 --> Cl- + H20 ---> No Hydronium/Hydroxide ions produced, therefore neutral Example two - the basic salt NaCH3COO or CH3COONa (doesn't matter which way you write it) Na+ + H20 --> Na+ + H20 CH3COO- + H20 --> CH3COOH + OH- ---> Hydroxide ions produced, therefore basic Example three - the acidic salt NH4Cl NH4+ + H20 --> NH3 + H30+ Cl- + H20 --> Cl- + H20 ---> Hydronium ions produced, therefore acidic __________________ Courses: Extension 1 + 2 maths, Chemistry, Physics, Modern History and Advanced English UAI aim: 99+ Click the user bars to join the groups of the era Want a friendly tutor with experience and plenty of resources? Click here, but hurry as there's only one slot left! Last edited by annabackwards; 30 Oct 2009 at 12:05 PM. Reason: Kaz picked up a typo :)

30 Oct 2009, 12:24 PM	#5 (permalink)
Aerath Prophet 9 <3 HSC: 2009 Gender: Male Location: Sydney Join Date: May 2007 Posts: 4,543 Last Activity: Yesterday, 9:44 PM	Re: Acidic, basic and neutral salts Ammonium nitrate methinks. __________________

30 Oct 2009, 1:35 PM	#8 (permalink)
harry4 Member HSC: 2009 Gender: Male Join Date: Sep 2008 Posts: 139 Last Activity: 15 Nov 2009, 4:21 PM	Re: Acidic, basic and neutral salts ohhhh i thought always thought it was just because it was a strong acid and weak base the resulting salt would be weakly acidic, had no idea about the water thanks

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