HELP --->>>CHEMISTRY QUESTION (***HELPED***)

[CaptainDanger]

O-LEVEL

JUNE 2008 PAPER 2 Q-B9

b-ii part...???

With explanation please...

Thanks in advance...

 

[PrInCeSs AshLeY]

Re: HELP --->>>CHEMISTRY QUESTION

Gimme its link.

 

[CaptainDanger]

Re: HELP --->>>CHEMISTRY QUESTION

http://www.xtremepapers.net/CIE/index.p ... 8_qp_2.pdf

 

[SalmanPakRocks]

Re: HELP --->>>CHEMISTRY QUESTION

Is there a explanation in the marking Scheme ??

 

[scouserlfc]

Re: HELP --->>>CHEMISTRY QUESTION

Wohoooooo i love chemistry so here u go the answer.

As you must be knowing that HCL is a stronger acid than Ethanoic acid so it does this work fast.
What stronger means is that HCL disassociates to its fullest potential while ethanoic acid cannot and when it disassociates it mostly takes much more time because hcl fully ionises while the other cannot do that ill tell u the whole thing clearly but i am in a hurry so see u.

 

[PrInCeSs AshLeY]

Re: HELP --->>>CHEMISTRY QUESTION

Hey scouserlfc I wanted to answer. I am in love with chemistry huh
Well, if you don't understand hi answer I'll explain ohk? :$

 

[CaptainDanger]

Re: HELP --->>>CHEMISTRY QUESTION

Oh I know that... Its second part sorry... Not iii... Its ii....

The same question....

PrInCeSs AshLeY you have a chance...

 

[CaptainDanger]

Re: HELP --->>>CHEMISTRY QUESTION

Is there a explanation in the marking Scheme ??

Its there but I need a little explanation about it?

 

[Sehrish]

Re: HELP --->>>CHEMISTRY QUESTION

By solving part (i), we got to know that Mg is in excess and dat HCl is the limiting reactant.

We use limiting reactant to determine mass etc of the product cux anything that is limiting reactant tends to finish earlier (since itx in a lesser amount) so the reaction depends on limiting reactant. Itx example is very much like a shopkeeper has ten pens but 5 covers of the pen, hence he will only b able to sell 5 pens since his sale (and in terms of chemistry, reaction) depends on covers of the pen since itx in a lesser amount.

Ok coming back to the question,
The molar ratio of HCl and MgCl2 is 2:1 (by equation)
Therefore if there are 0.01 mol of HCl, moles of MgCl2 shall be the half ie; 0.005 mol
Now that we know the moles of MgCl2 we can find itx mass by Mol= Mass/Mr
Mr of MgCl2 is coming to be 95;
So mass is 0.005 X 95 = 0.475 ----> 0.48 g

 

[scouserlfc]

Re: HELP --->>>CHEMISTRY QUESTION

Arey yaar itna aasan to hai.

 

[CaptainDanger]

Re: HELP --->>>CHEMISTRY QUESTION

Thanks Alot Sehrish for that explanation...

&

scouserlfc

I got the ratio wrong I guess... But that explanation really helped...


Kabhi kabhi aasan chezon main atak jata hai insan... Thanks anyway...

 

[scouserlfc]

You are right captain danger,
but one thing u should note that since magnesium is in excess so taking it to calculate the mass of MgCl2 is wrong as it is in excess so u always take the mass of the thing that is not in excess in this case HCl but yup u already understood so good luck in Cie.

 

[Sehrish]

np im glad it helpd

 

[CaptainDanger]