CHEM AND BIO HELP AND TIPS HERE

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IGCSE Paper 3 Question 4 (b) (ii)

It says draw the new graph. How do u know where to draw the graph till. In the ms it says it should be drawn till 8cm3. How do u obtain this value and why this value ?

Help and plz explain well !!

Hey ari!!
could you also specify the year??

[holtadit]

woops... 2004 may jun

I simply dont get it at all

[Ghost Of Highbury]

this q irritated me a lot during my IGs

heres it..

first--> remember to use mole ratio in these types of Qs

the no. of moles of hydroxide ions => moles = conc. * vol = 1 * 12/1000 (i took 12 because at 12cm^3 in the x-axis the graph becomes constant, meaning anything further is an excess) = 0.012

the no. of moles of chloride ions = 1* 4/1000 = 0.004

mole ratio : 0.004:0.012 = 1:3

---------------------
Fe2+ + 2OH- = Fe(OH)2

from the above , u know that the mole ratio is 1:2

4.0 cm3 of aqueous iron(II) chloride = 0.004 dm^3

no. of moles of chloride ions = 1 * 0.004 = 0.004 moles
let the no. of moles of hydroxide ions be 'x'

therefore, 1:2 :: 0.004 : x

x = 0.008 moles of hydroxide ions

volume = moles/conc. = 0.008/1 = 0.008dm3 = 8cm3

so the shape shud be the same but it shud go constant at 8cm^3

[holtadit]

orry for taking so long...some important calls
Anyway

Na3PO4+ nTx(NO3)y----> NaNO3+ Thanks(PO4)z

all the variables are unknown at present

U know the reaction will give sodium nitrate which has the formula NaNO3[/sub]....now u also know the volume of the product is 8cm3
the volume of sodium phosphate is 2cm3...
The mole ratio of sodium phosphate and Tnitrate is 2:3, when u try to balance for NaNO3...and u get (NO3)2. The product side has 6NaNO3
This gives us the charge on T as +2...since (NO3)2-...u know PO4 will be twice and thus T will be thrice cuz of the charges
 
Little weird to understand...ill put down the balanced equation, which is likely to make it easy for u to figure it out

2 Na3PO4+ 3 T(NO3)2---->6NaNO3+ T3(PO4)2

I'll try explaining again...i tried my best to explain tho...

nid, im sorry i still dont get it..

[Saladin]

The ansa is attatched.

Hope this helps.

[holtadit]

I didn't

[SGVaibhav]

The ansa is attatched.

Hope this helps.

ansa
nice word

[nid404]

@dude- Maybe U r smart enough to understand....but u do not talk to any1 like that. I'm sorry but it is my duty to inform u that this is your 1st official warning

@aadi- unfortunately u haven't performed you duty well

@ Ari- If you still do not understand, lemme knw...I will try n explain it yet again And if there is anything that u find offensive, plz report the post and I will surely look into it....And im sorry I saw this a lil late

[Saladin]

For some ppl, they need to be insulted to actually work, that is a simple question, and is fully explained even n the book both Adi and I helped Ari out, and we explained every bit, but if he still does not get it, then he is hopeless, it was a simple thing. I saw both my and Adi's explanation and we both explained all the parts. Now even after that if he does not get it, he is definitely hopeless!!!!

Secondly, the word that I have used has been used may times, no body has been given a warning for that, I do not expect to be either. Furthermore, it was in an attachment!

so, if u can stop being such a goody-two-shoes then that would be helpful. Wat u do nid is something called spoon feed ppl! That results the person being even more dependent on u as a result! wat will happen to ari when he has to rely on himself???

Sure he did not like it, but I am sure it gave him some incentive to work it out by himself and not give up!
My purposes were that of psychological change to change how he works, not to insult him!

Moreover, telling another moderator whether he has done his duty or not is a matter of perspective, as much as I respect urs, u shud respect mine!

Lastly, if u have something against me, or just that u are over-sensitive about an issue please tell me in a pm, that is what they are for!

@ari, its a joke man, and something to actually get u working! Dont take it so seriously!

[nid404]

Well if some1 takes time to understand, it doesn't mean he/she is hopeless.......
You need to be aware that not every1 here is a 98-99%.....

If there have been cases of others using that word in such circumstances, I would definitely take action...You can send me the link if you have seen the word being used to humiliate other members

If he were to do it by himself, why would he join the forum in hope of some help from others. I'm sure if he understands this, he will be able to do similar questions. But If he doesn't understand this, there will be more of the same type comin in(and when u answer each one of it for him, that's when u call it spoon-feeding) and that's when ur frustration grows...It would be better if he gets it now....
And if u change that tone of yours, I will be obliged
It may be simple for u....He is not the same as you

And to that psychological change u wanted to bring about...there are better ways to motivate ppl to work harder and analyse things for themselves
No personal grudges or anything if u think there is....just to make it clear...I'm just doing my job

Thanks.
And there will be no more discussion about this on this thread.
P.S. If u want to amend any of these rules, you can make a suggestion

[holtadit]

WOW !!! I make one statement and we have a war going on.

I know all discussions regarding this were supposed to end with nid's post BUT lets set the record straight :

1.) The Dude 321 you have a very brusque manner of dealing with people... many people would infer that you are being an arrogant twat BUT I know that you aren't. I understand you were trying to help me and that you felt you were helping 'motivate' me.

THUS, I have a message for you. I dont need to be 'motivated' by you... I am not a 4 year old and it just so happens that I am not a HOPELESS case when it comes to chemistry or any subject as a matter of fact. I am darn good at my studies and I plan on getting all A*s

Now if u have a FUC***n* problem with that then I suggest you simply ignore my kind of people and carry on with your life...

2.) Thank you nid and aditoxic for your help in math and chem.

                                                                             THE END  

[Ghost Of Highbury]

@dude- Maybe U r smart enough to understand....but u do not talk to any1 like that. I'm sorry but it is my duty to inform u that this is your 1st official warning

@aadi- unfortunately u haven't performed you duty well

@ Ari- If you still do not understand, lemme knw...I will try n explain it yet again And if there is anything that u find offensive, plz report the post and I will surely look into it....And im sorry I saw this a lil late

I answered his doubt and I consider that as my duty. You have just typed an extremely meaningless generalized statement.

[Saladin]

Typing in arguments is not what I do, in-fact it bores me. I mean not to be arrogant and not to be rude. I have always tried to help people, many people have taken my examples and still thank me for the things that I do. Aadi being just one of them.

Now, back to business. I understand that both you me and Aadi are mods. I would kindly and sincerely like you Nid404, to understand that we do not need to be taught how to handle people! Furthermore, you do not have the right to give me a warning under any circumstances, that is the sole authority of an administrator, if you would like to consult with them, please do so or simply 'get a life'. To begin with, Aadi explained it perfectly fine, perfectly, it was the best explanation that he would get! I doubt that anyone will provide such a dedicated answer. But people totally miss the point of this, it was a joke and to some extent a motivating factor! That was its purpose!

Again I will stress, you are no more superior to me or to Aadi! Wielding an axe does not mean that other weapons are inferior, and other skills are inferior. Try to understand that the 'greatness' with which you handle your job is no more than simple oversensitiveness. Kindly refrain from making commands, I am not obligated to execute yours, and neither is Aadi.

[SGVaibhav]

to come back to the chemistry topic

how is

2H + O ---->   H₂O

it should be either     2H+O
or it should be
                             2HO

haha
silly doubt

[Ghost Of Highbury]

ok lets stop it here and discuss in the lounge. this isnt the right place to be doing so. no offence, Respect

@vaibhav --> 4H + O2 --> 2H2O