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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: helloworld123 on July 24, 2012, 10:38:23 pm

Title: Equilibrium SAC Rates of reaction heplplp
Post by: helloworld123 on July 24, 2012, 10:38:23 pm

What are the effects of adding the list below to the following equation?

Fe3+   + scn-     ><  Fe(SCN)2+ ; exothermic   btw   F- IONS CONVERTED FE3+ TO FEF63-           Ag+ and SCN-   PRECIPITATE AgSCN

fe pale yellow               scn- colorless              fescn2+ red

By adding:( Predictions on what i think) plz tell if right or wrong

Fe3(NO3)3   
not sure

KSCN
colorlesss?

NaF
not sure

AGNO3
lighter no loner fe(SCN) BUT AG(SCN)

Water
system has been diluted and system will go backwards therefore lighter


Whats is going to happen?


thanks

Title: Re: Equilibrium SAC Rates of reaction heplplp
Post by: Jenny_2108 on July 24, 2012, 11:11:45 pm

Do you go to the same school with me?
Because we will have chem SAC about rate of reactions next week and my teacher gave us exactly this question today :P
Here is the attachment of the answer, if you dont understand, I can explain further

Title: Re: Equilibrium SAC Rates of reaction heplplp
Post by: helloworld123 on July 25, 2012, 12:35:58 pm

no i go to a school in orbost lol.

could u explain why this happened red----> colorless using le chantliers principle plz

thx

Title: Re: Equilibrium SAC Rates of reaction heplplp
Post by: Jenny_2108 on July 25, 2012, 06:55:35 pm

Quote from: helloworld123 on July 25, 2012, 12:35:58 pm

could u explain why this happened red----> colorless using le chantliers principle plz

which part is it? whats the change?

Title: Re: Equilibrium SAC Rates of reaction heplplp
Post by: helloworld123 on July 25, 2012, 07:05:58 pm

ok heres my understanding:)

Fe3+ + SCN-(aq) = [Fe(SCN)]2+

Make up a solution of Fe3+ and SCN-.
Pour into test tubes.
To each test tube add: Fe3(NO3)3; KSCN; NaF, AgNO3, WATER
Watch for a reaction.

by adding water system will go backwards towards most particles hence appearing more pale
Agno3- a product has been substitued and hence not forming the red solution Fe(SCN)2+ normally would hence red

Im not sure for the rest:(

thanks:)

Title: Re: Equilibrium SAC Rates of reaction heplplp
Post by: Jenny_2108 on July 25, 2012, 07:54:14 pm

From Le Chatelier's principle, when the system is changed at equilibrium, it will act to partially offset the change

1. Adding Fe(NO3)3=> [Fe3+] increases, shifting the reaction to the right => more red

2. Adding KSCN=> [SCN-] increases => forwards reaction=> more red

3.Adding NaF=> FeF3 precipitated=> [Fe3+] decreases=> backward reaction=> less red/ more pale yellow

4. Adding AgNO3=> AgSCN precipitated=> [SCN-] decreases=> backward reaction=> less red/ more pale yellow

5. Adding H20: yep, you are right :)

Correct me if I'm wrong.