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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: LeFowl on June 18, 2009, 01:14:44 AM

Title: Electrolysis NaCl
Post by: LeFowl on June 18, 2009, 01:14:44 AM

At the end of an electrolysis with an electrolyte of concentrated NaCl sol'n and inert elctrodes, will the electrolyte be acidic,neutral or basic????

Title: Re: Electrolysis NaCl
Post by: Borek on June 18, 2009, 02:57:37 AM

Write reaction equations.

Title: Re: Electrolysis NaCl
Post by: LeFowl on June 18, 2009, 11:16:05 AM

2Cl-(aq) -2e-  :rarrow: Cl2(g)
2H+(aq) +2e-  :rarrow: H2(g)

Title: Re: Electrolysis NaCl
Post by: killer120 on June 18, 2009, 11:48:22 AM

2Cl-(aq) -2e-  right arrow Cl2(g)
2H+(aq) +2e-  right arrow H2(g)
i think if the electrolysis experiment really continue until the end...the electrolyte will become basic because there will be a lot OH- ions inside it.....am i right? ???

Title: Re: Electrolysis NaCl
Post by: LeFowl on June 18, 2009, 11:49:44 AM

well i had a test yesterday and that was one of the questions XD. i put basic. we didn't even do this sstuff in class

Title: Re: Electrolysis NaCl
Post by: LeFowl on June 18, 2009, 01:42:48 PM

so can anyone tell me whether it will be acidic, neutral or basic?

Title: Re: Electrolysis NaCl
Post by: Stephen on June 18, 2009, 03:29:37 PM

Quote from: LeFowl on June 18, 2009, 01:14:44 AM

At the end of an electrolysis with an electrolyte of concentrated NaCl sol'n and inert elctrodes, will the electrolyte be acidic,neutral or basic????

Well, if I understand question well(not from USA or etc)....I'd say neutral...
You know that NaOH is strong base and HCl is strong acid ==>there is no electrolysis and there is going to be neutral solution....But this is just if i understood question good:D

Greetings

Title: Re: Electrolysis NaCl
Post by: Borek on June 18, 2009, 03:32:14 PM

killer is right.

Think: where does H⁺ come from? What must be left in the solution?

Title: Re: Electrolysis NaCl
Post by: LeFowl on June 18, 2009, 07:31:07 PM

Thanks alot =D

Title: Re: Electrolysis NaCl
Post by: dufengtao on June 18, 2009, 10:52:23 PM

NaCl+H₂O :rarrow:Cl₂+H₂+NaOH. This equation has the answer in it's production.

Title: Re: Electrolysis NaCl
Post by: 408 on June 19, 2009, 01:13:20 AM

Note that while you may think H2O is the strongest reducing agent present which would end up giving H+ to cancel the OH-, H2O needs an overpotential, so Cl- oxidation is preferred, giving Cl2.

Some Cl2 will react with the NaOH giving hypo chlorite and chlorate, but the amount that escapes means the cell goes basic.

Overpotential see here: http://en.wikipedia.org/wiki/Overpotential

Title: Re: Electrolysis NaCl
Post by: killer120 on June 19, 2009, 02:35:17 AM

but i got one question to ask you all....actually where does the water (H+ and OH-) come from?i thought the NaOH solution is concentrated....so why still has water exist in the solution?can you all help me?explain to me... ???

Title: Re: Electrolysis NaCl
Post by: Borek on June 19, 2009, 02:45:13 AM

Quote from: killer120 on June 19, 2009, 02:35:17 AM

actually where does the water (H+ and OH-) come from?i thought the NaOH solution is concentrated....so why still has water exist in the solution?

As long as it is solution it contains water (or some other solvent) by definition.

I am not sure what your problem is.

Title: Re: Electrolysis NaCl
Post by: pip on June 27, 2009, 11:16:02 PM

Electrolysis of saturated sodium chloride is THE lab synthesis of sodium chlorate all this Cl2 and H+ talk seems unlikely as H2 is formed not H+

NaCl + 3H2O → NaClO3 + 3H2