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A2 OCR Chemistry B F334 - June 2015

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guys just a random question.

Are we supposed to know how to name complex ions? (eg. hexaaquacopper(II) ion). The naming rules are just killing me.

Yes and also the colour. I ahd to do it in one of the Exam papers.
http://www.chemguide.co.uk/inorganic/complexions/names.html

Reply 301

suyoof123

Original post by kevintai0901

guys just a random question.

Are we supposed to know how to name complex ions? (eg. hexaaquacopper(II) ion). The naming rules are just killing me.

Yes we are,

Name the ligand/s first with the prefix for how many , then name the transition metal and depends if its negative or neutral/positive on what version of the name it will take along with the oxidation state.

Reply 302

MathsAddict

Original post by radhikagulati

What's the difference between a by-product and waste product? I saw it in an F335 paper somewhere and it could come up in f334 i guess

(sorry for posting loads I'm annoying i know)

By product is a result of a reaction i guess it could be useful? a waste product has no use so its a waste product but i am sure someone will use f332 revise book that i lost to give you a better answer.

Reply 303

MathsAddict

I am gonna sleep at 3am i know i won't be able to sleep and go college at 10:30 for a revision session.

Reply 304

chemistrykid123

Original post by EggsterminateMe

Hey Chem kid! Yes yes I remember you. (I wonder how the others are) I also got a C and also retaking F335. All of this is gonna be a pain in the butt for me. I feel as if i knew more last year than this.

Good good I'm glad, yes I bet they are great we had an actual amazing (and interesting) group last year, it does not feel as daunting now I know somebody going through with me, I know what you mean I have not been revising intensely as I did last year trying to go with the calm relaxed approach this time. You ready?

Reply 305

radhikagulati

Original post by MathsAddict

Thanks!

Reply 306

Anonymous696061

Original post by KittenMittens

Do you have bullet points for the process of doing a titration, its the practical technique i'm least familiar with and I don't think its in the notes you made? The notes are great btw so thanks! :smile:

Aww, thank you, & sure!

Acid-base titration:
1 - Fill your burette to zero with the solution of known conc (-in all the scenario is I've seen, this is usually the alkali).
2 - Using a pipette, transfer a known volume of your solution of unknown conc into a conical flask (-again, this is usually the acid from the scenarios I've seen!).
3 - Add in a few drops of suitable indicator, such as methyl orange or phenolphthalein. (-ONLY if it is a titration that requires indicators! Titrations with potassium permanganate do not require any indicators!)
4 - Start the titration, swirling the conical flask throughout; when you first see a colour change, immediately turn down the tap on the burette, so the solution of known conc is added drop-wise.
5 - When a permanent colour persists for 20 seconds, stop the titration & record the titre value in a table. (-For permanganate titrations, the end of the titration will be 'when a permanent pink'.)
6 - Repeat the titration until you have 2 concordant results (i.e. 2 titres within 0.1cm^3 of each other), then calculate the average of these titres.

There are 2 redox titrations in F334:
-Potassium manganate(VII) titrations - this an additional step of acidifying the solution of unknown conc, after transferring into the conical flask (step 2 above) -the rest of the steps are the same. (-KMnO4 is a strong oxidising agent, so can be used to find conc's of solutions containing Fe2+ ions or H2O2, through redox titrations.)

-Iodine-thiosulfate titrations - this is used to determine the conc of oxidising agents; it involves an additional step BEFORE carrying out the titration above: react a known vol of the oxidising agent with an excess of acidified potassium iodide solution. The iodine that is produced can then be titrate against sodium thiosulfate; also, towards the end of the reaction, add a few drops of starch solution. This will give an intense blue-black colour that will fade to clear at the end point.

Sorry this is so long, I hope it helps!

Reply 307

thedontom

My revision guide says polydentate is more than two coordinate bonds formed, but isn't it two or more? (or more than one?)

Reply 308

Shostakovish

Don't worry people.
Don't worry.
I will be here to lower the grade boundary.
You are all welcome.

Reply 309

nats927

if something has 4 pairs of electrons how do you know if its square planar or tetrahedral?

Reply 310

MathsAddict

some help me on june 2012 5 b iii how is it a cordination number of 6 i know edta4- is a polydentate so how many bonds can it form? 6? why 6 why not 4?

(edited 8 years ago)

Reply 311

ThePhoenixLament

Original post by nats927

if something has 4 pairs of electrons how do you know if its square planar or tetrahedral?

You don't- the mark scheme allows for both

Reply 312

MathsAddict

Original post by thedontom

My revision guide says polydentate is more than two coordinate bonds formed, but isn't it two or more? (or more than one?)

more than 2 is polydentate 2 is bidentate

Reply 313

nats927

Original post by ThePhoenixLament

You don't- the mark scheme allows for both

cool thankss

Reply 314

anni101

Original post by chemistrykid123

same, trying to be more relaxed. And I believe many people got Cs in chem due to f334. But, in sha allah, this time there will be success!!

Reply 315

Jaz_ace

do we really have to know how to name ligands, havent seen a past paper question about it???

Some notes.

Original post by Jaz_ace

do we really have to know how to name ligands, havent seen a past paper question about it???

dont take any chances they might exploit weak points revise it as well know everything and enter the exam confidently.

Reply 318

kingcobra007

Original post by MathsAddict

some help me on june 2012 5 b iii how is it a cordination number of 6 i know edta4- is a polydentate so how many bonds can it form? 6? why 6 why not 4?