Edexcel Chemistry Unit 5 June 19 2012
Chemistry exam discussion - share revision tips in preparation for GCSE, A Level and other chemistry exams and discuss how they went afterwards.
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Re: Chemistry Unit 5 June 19 2012I dont get the ms for that question at all.. like idk where they're coming from with the answers(Original post by This Honest)
Not so much jun10 but jan 11 caused some problems such as the last Q and the dry oil Q
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Re: Chemistry Unit 5 June 19 2012You only need a D as you as said way earlier so you should be fine!(Original post by EffKayy)
LOL :/ Yeah the dry oil question
I hope this paper is OK, im a little scared now as the unit 4 paper seemed quite challenging in some parts -
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Re: Chemistry Unit 5 June 19 2012When you want to obtain something dry, most like a drying agent would be present such as anhydrous MgSO4(Original post by shahofiran)
I dont get the ms for that question at all.. like idk where they're coming from with the answers
They said adding water to oil so you add them then put them in a separating funnel.
That's all I understandLast edited by This Honest; 14-06-2012 at 17:31. -
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Re: Chemistry Unit 5 June 19 2012What determines if something is square planar or tetrahedral in shape? I know its related to it having co-ordination number of 4, but in the pearson book it also mentions how having complete d orbitals means its tetrahedral - like cobalt. It then says co-ordination number of 4 with incomplete d orbitals, like copper nickel etc. result in square planar. I dont get what it means by complete and incomplete d-orbital??
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Re: Chemistry Unit 5 June 19 2012d subshell.(Original post by shahofiran)
What determines if something is square planar or tetrahedral in shape? I know its related to it having co-ordination number of 4, but in the pearson book it also mentions how having complete d orbitals means its tetrahedral - like cobalt. It then says co-ordination number of 4 with incomplete d orbitals, like copper nickel etc. result in square planar. I dont get what it means by complete and incomplete d-orbital??
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Re: Chemistry Unit 5 June 19 2012could you please explain it fully? I really dont get it at all, like i cant visualize it.(Original post by sconter)
d subshell. -
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Re: Chemistry Unit 5 June 19 2012Think this is to do with the Born Haber cycle.. but can't really remember,(Original post by shahofiran)
Also, why is Mn(II) more stable than Mn(III)?
possibly to do with the fact that its more exothermic on its formation
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Re: Chemistry Unit 5 June 19 2012I figured it out; Mn2+ is more stable since its electrons are in 3d orbitals (5 electons each of which singly occupy one orbital) . Mn3+ is where 4 orbitals are singly occupied by each of 4 electrons. Mn 2+ is more stable because you need more energy to remove that extra electron.(Original post by EffKayy)
Think this is to do with the Born Haber cycle.. but can't really remember,
possibly to do with the fact that its more exothermic on its formation
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Re: Chemistry Unit 5 June 19 2012Mainly everything organic.(Original post by rvp123)
Anyone know what the synoptic parts tend to be, i need to nail that part to secure an A -
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Re: Chemistry Unit 5 June 19 2012Yep, the strongest oxidising agent has the largest positive electrode potential value. Remember, an oxidising agent is one which oxidises another species but is reduced itself.(Original post by keerthi3)
Guys, does the strongest oxidising agent have more postive standard electrode potential value?
For example,
1/2Fe2 + e- -> F- E = +2.87V
1/2I2 + e- -> I- E = +0.54V
Which one is the strongest oxidising agent and why? -
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Re: Chemistry Unit 5 June 19 2012Thank you(Original post by NutterFrutter)
Yep, the strongest oxidising agent has the largest positive electrode potential value. Remember, an oxidising agent is one which oxidises another species but is reduced itself.
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Re: Chemistry Unit 5 June 19 2012why does vanadium and nickel both have [Ar] 3d3 4s2 and [Ar] 3d8 4s2 electron configuration respectively because i would have guessed it would be [Ar] 3d5 4s0 and [Ar] 3d10 4s0 as i thought that would have made them both more stable
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Re: Chemistry Unit 5 June 19 2012I get confused on this too. Our teacher has told us that if the coordination number is 4, assume its Tetrahedral, unless the compound is Pt(NH3)2Cl2 which is the one we have to know as being square planar (and also (NiCl4)2-)(Original post by shahofiran)
What determines if something is square planar or tetrahedral in shape? I know its related to it having co-ordination number of 4, but in the pearson book it also mentions how having complete d orbitals means its tetrahedral - like cobalt. It then says co-ordination number of 4 with incomplete d orbitals, like copper nickel etc. result in square planar. I dont get what it means by complete and incomplete d-orbital??
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Re: Chemistry Unit 5 June 19 2012basically if there is only one type of ligand its going to be tetrahedral and if there are two different types of ligands its going to be square planar. thats how ive learnt it(Original post by giraffegiraffe)
I get confused on this too. Our teacher has told us that if the coordination number is 4, assume its Tetrahedral, unless the compound is Pt(NH3)2Cl2 which is the one we have to know as being square planar (and also (NiCl4)2-) -
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Re: Chemistry Unit 5 June 19 2012For questions like this that has nothing to do with chemistry just read through the passage and normally tells you what to write. For example in the passage it says in india/holland they used to grow their own dyes - if there are now quicker/easier/cheaper methods it means less people will buy the dyes from india/holland as its more expensive so they make less money = lower gdp = lower employment etc(Original post by This Honest)
Can some please explain to me Q24aii on Jan 12.
Sorry, can't post link, only have hard copy -
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Re: Chemistry Unit 5 June 19 2012Hi i was doing one of the older papers and one of the TM question asked when a compound known as F (containing empirical formula Cu2SO6H2) was dissolved in dil HCL acid, the resulting blue solution gives a white ppt with barium chloride solution. Suggest a formula for F given that all the hydrogen is present in hydroxide ions.
Firstly, I don't get the bit about hydrogen ions and secondly, the answer was CuSO4.Cu(OH)2...
are we supposed to know these types of complexes specially containing sulphate? :/ or is this off the syllabus now?
