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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: Destiny on May 11, 2012, 05:46:30 pm

Title: Erm hydrolysis?
Post by: Destiny on May 11, 2012, 05:46:30 pm

I know hydrolysis is the breakdown of a molecule when water is added to it... but since when did adding water to ethene becoming hydrolysis? u-u The heinemann 2 workbook has a question on pg 77 Question 2 reaction 7... And so does the NEAP study guide on pg 64 (Exam 1 Question 3aiii)

I wonder what you guys think as both my tutor (a past examiner) and my teacher (a current examiner) say that it's technically not hydrolysis...
Or perhaps it's the textbook conspiracy :/

Title: Re: Erm hydrolysis?
Post by: charmanderp on May 11, 2012, 06:38:51 pm

AFAIK you're very much correct, hydration and hydrolysis are completely different!

Title: Re: Erm hydrolysis?
Post by: Bismuth on May 11, 2012, 08:19:02 pm

Yeah, it's simply an error. There's one (not sure for the new version) in the Heinemann textbook as well.

I take it you know what you're talking about now, but for future reference: Difference between Hydration and Hydrolysis?

Title: Re: Erm hydrolysis?
Post by: yellowsone31 on May 11, 2012, 09:39:51 pm

Yes you are right in saying they are different. Hydrolysis refers directly to the breaking down process of a molecule when it reacts with water (hydro meaning water and lysis meaning splitting). In hydration, water molecules are added to the substance, however, in contrast to hydrolysis no breaking down occurs.

Title: Re: Erm hydrolysis?
Post by: charmanderp on May 11, 2012, 10:20:14 pm

Hydration = Addition - you get one product and retain mass of both reactants.

Hydrolysis = breaking - you get two products.

Title: Re: Erm hydrolysis?
Post by: Mao on May 12, 2012, 12:35:04 pm

The definition of hydrolysis vs hydration is still a bit iffy.

Generally, hydration is the addition of H/OH across a double bond, i.e. ethene + water

Hydrolysis takes place whenever water participates in a substitution reaction. I.e. XY + H2O --> XOH + HY
A couple of examples:
CH3CH2Cl + H2O --> CH3CH2OH + HCl, in here, -OH substituted -Cl
CH3CH2OCH2CH3 (ether) + H2O --> CH3CH2OH + HOCH2CH3, in here, -OH substituted -OCH2CH3

Title: Re: Erm hydrolysis?
Post by: charmanderp on May 12, 2012, 01:24:53 pm

Ethanoic anhydride is another slightly confusing instance of hydrolysis which is part of the VCAA course.

Title: Re: Erm hydrolysis?
Post by: Destiny on May 12, 2012, 08:50:18 pm

._________. Thanks guys :3
Yeah, it's the bit that's a bit grey.  Well, if there's only one product (e.g. addition) I'm just going to put addition or hydration, and with two products, I'll do substitution if I can.  Ethanoic Anhydride... well, if it's two ethanoic acids + each other, I'll just put condensation (water loss).