h2 chem tys qns
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hi, i dont know how to do this qns at all -_- electrolysis of concentrated NaCl(brine) should only give Na and Cl2 right? but i saw the answer got OH or something one, i dont understand...thanks.
part b i said that steel contains metals such as iron that can react with the chlorine produced. should be correct i think. but for the rest of the questions on this page i have no clue :)
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The oxidation potential of Na is too positive (ie. the reduction potential of Na+ is too negative); hence Na+ will not be reduced to Na. Even in a concentrated solution, it is still a solution, and the solvent water molecules will be reduced at the cathode to generate hydrogen gas and hydroxide ions. Cl2, H2 and NaOH are produced in the molar ratio of 1:1:2. This industrial process is used to manufacture 3 different useful products of chlorine, hydrogen and sodium hydroxide. As to the purpose of the diaphragm : "In diaphragm cell electrolysis, an asbestos (or polymer-fiber) diaphragm separates a cathode and an anode, preventing the chlorine forming at the anode from re-mixing with the sodium hydroxide and the hydrogen formed at the cathode." http://en.wikipedia.org/wiki/Chlorine_production#Diaphragm_cell_electrolysis_.28Bipolar.29 You should also be able to write the equations for these undesirable reactions that would occur, should the diaphragm be absent, if the question asks for it.
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oh, so the diaphragm prevents Cl2 and OH- ion to react in the disproportionation reaction of Cl2 we learnt in Grp 7? but is it the hot reaction or cold reaction?
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In the exams, if the temperature is not stated, write both with qualifications. That is, don't just write the equations, but write the equations with the relevant temperatures clearly stated in each case.
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huh. so electrolysis of concentrated and dilute NaCl will give the same thing?! .....
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Depending on the exact molarity, very dilute NaCl(aq) will see mainly water or hydroxide ions oxidized at the anode, rather than chloride ions.
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Is HCl a product formed ?..
H2(g) + Cl2(g)--> 2HCl(aq) ??
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Originally posted by arxoz:
Is HCl a product formed ?..
H2(g) + Cl2(g)--> 2HCl(aq) ??
Hi arxoz,
I believe H2(g) + CI2(g) ===> 2HCI(g)
Please do pardon me if I am wrong, it has been more than 10 years since I did chemical equations.
Cheers.
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That's right. Hydrogen chloride gas would dissociate to ionize during hydrolysis forming hydrochloric acid.