Acidic, basic and neutral salts (1 Viewer)

[jackc91]

Why are some salts acidic, basic and neutral?

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

but why?

 

[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

 

[kaz1]

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]

*fixed.

Hehe, thanks for the pick up

Just wondering, anyone know of any other acidic salts?

 

[Aerath]

Ammonium nitrate methinks.

 

[annabackwards]

Ammonium nitrate methinks.

Thanks

 

[jackc91]

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]

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]

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]

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

 

[markbradfield]

Re: Acidic, basic and neutral salts - EasyChem answer

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Here is a page containing a succint explanation of the above, with some good quality equations:


http://www.easychem.com.au/the-acidic-environment/acid-base-definitions/salts-and-solutions


Cheers,
M

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[~Fire Jade~]

Re: Acidic, basic and neutral salts - EasyChem answer

Completely Random acid and bases question:
1) If [H+] is 10^2 times of [OH-] what is the pH of the solution?
2) 1.68 KOH is dissolved in water to make 0.3 Litre of solution. Calculate the pH of the solution? (KOH= 56)===> FIGURED OUT THIS ONE...NO WORRIES XD

 

[Pwnage101]

Re: Acidic, basic and neutral salts - EasyChem answer

1)

[H+][OH-]=10^-14, but we know [H+]=100[OH-]

Thus we have 2 equations in 2 unknowns, which can be solved by substitution:

{100[OH-]}[OH-]=10^-14
100[OH-]^2=10^-14
[OH-]^2=10^-16
[OH-]=(10^-16)^0.5=10^-8
[H+]=10^-14/[OH-]=10^-14/10^-8=10^-6

pH=-log_10{[H+]}=-log_10{10^-6}=(-6)(-log_10{10})=(-6)(-1)(1)=6 I think...

2)

I think some words are missing:
"1.68 [missing word - 'grams' perhaps?] KOH..."

 

[~Fire Jade~]

Re: Acidic, basic and neutral salts - EasyChem answer

Thank you so much~ Does anybody know how to do the second one??

 

[~Fire Jade~]

Re: Acidic, basic and neutral salts - EasyChem answer

Another question I want to ask is that:
a solution was made by dissolving 5.13g of X(OH)2 in 6L final volume if pH of the solution was 12; what is the atomic weight of X=? (O= 16 and H=1 )

 

[~Fire Jade~]

Re: Acidic, basic and neutral salts - EasyChem answer

1)

[H+][OH-]=10^-14, but we know [H+]=100[OH-]

Thus we have 2 equations in 2 unknowns, which can be solved by substitution:

{100[OH-]}[OH-]=10^-14
100[OH-]^2=10^-14
[OH-]^2=10^-16
[OH-]=(10^-16)^0.5=10^-8
[H+]=10^-14/[OH-]=10^-14/10^-8=10^-6

pH=-log_10{[H+]}=-log_10{10^-6}=(-6)(-log_10{10})=(-6)(-1)(1)=6 I think...

2)

I think some words are missing:
"1.68 [missing word - 'grams' perhaps?] KOH..."

Um yeh, there is 1.68 grams of KOH.....

 

[~Fire Jade~]

Re: Acidic, basic and neutral salts - EasyChem answer

1 More question
A solution was made by dissolving 5.13g of X(OH)2 in 6L final volume if pH of the solution was 12, what is the atomic weight of X=? (O=16 H=1)