CHEM AND BIO HELP AND TIPS HERE

[WARRIOR]

@Larimeeva  I strongly suggest lowering your tone; we are all here to help you, but we are NOT OBLIGED to help you.

Respect others and treat them fairly; most importantly be NICE.

my headphones almost blew my ears there ! thanks ari =.=  

[the_grim_reaper]

Why is everyone misunderstanding it. Fine, let me rephrase the whole thing in a language that everyone can understand.
I know like hell that cracking goes like this [Alkanes --> Alkene + Hydrogen]. This part understood?

Now in the Mark scheme they say that the answer to my question should be Alkane --> Alkene + Alkane + Hydrogen.

Get it? Now I want to know why they stated Alkane as a product in cracking. I'm not asking for a miracle.

So here's the link, and I hope a sensible person can answer me.
https://studentforums.biz/index.php/topic,54.msg253414.html#msg253414

Lady the mark scheme I have gives two options. alkene + alkane OR alkene + alkene + hydrogen. Now butene is the alkene and you can then have alkane which is hexane!!! What is wrong with that?? You can have an alkane as a product! As long as an alkene is made cracking is happening!!!

Now if you want to add hydrogen to it, then its butene, hydrogen and hexene (aka alkene+alkene+hydrogen)!!! You cant have an alkane here.

I'm not doing a miracle ...

[Dana]

Only gases huh? Lol, ryte, so in that case we can guess how much of something is formed (the volume) using the mole ratios? Thx..

yuup, learnt that from here too

[Raywin]

Ugh sigh , OFCOURSE Magnesium HYDROXIDE EXISTS OBVIOUSLY.. BUt where talking about the products when magnesium reacts with water .. its MgO sorry to disappoint you and your wiki

Lol i tot u were trying to say tht it doesnt exist.. hahaha.. XD

[MasterMath]

omg no it can form both! cuz there are diff types of lime slaked lime, quicklime, limestone

Well it forms CaO  just memorize it then

[Raywin]

take this reaction for example:
    2N₂     +      3H₂   -----> 2NH₃
          56g                            6g                         34g
Now you can use this for example if they tell you we gave you 5.6g of nitrogen.. how many grams will be produced of hydrogen
Then you can do this
      56              6
      5.6             x
then find X by .. (5.6*6)/56
The same can be done
If you change it
The mole ratio is simply the co-officent of the reactants and products
        2                                        3                             2
just follow the same if they give you a specific amount of moles of reactant/product!

Thanks a lot..

[elemis]

my headphones almost blew my ears there ! thanks ari =.=  

LOL ! Okay, your welcome.  The Lion exists to serve and protect his domain. 

I'm always watching.

[igext]

what conditions of rxns do we need to know other than contact and haber processes?
especially organic equations (e.g.cracking and polymerisation) do we need to know conditions for these?

[Dana]

Yo, I needed to ask, why does water act as a base when Sulphuric Acid dissolves in it?

cuz it accepts a proton!! (H+) WOO

[8T]

Could someone please explain may june 09 paper 32 q 5 b
I know it's for instance K3PO4 or T3 PO4.. but the other 2 marks not quite so any help??

Could someone pleaaaaaaaase answer i quoted above ? :S??

[MasterMath]

Could someone pleaaaaaaaase answer i quoted above ? :S??

YOu hvave to show that you know that the reaction ends at the 12 cm³ and the other i dont know i dont remember the question 8-)

[igext]

LOL ! Okay, your welcome.  The Lion exists to serve and protect his domain. 

I'm always watching.

what conditions of rxns do we need to know other than contact and haber processes?
especially organic equations (e.g.cracking and polymerisation) do we need to know conditions for these?

[MasterMath]

what conditions of rxns do we need to know other than contact and haber processes?
especially organic equations (e.g.cracking and polymerisation) do we need to know conditions for these?

haber : 450C and 200 atm .. iron as catalyst ( Finely divided)
Contact: 450C 2 atm.. Vanadium (V) oxide
Cracking : Al₂O₃/SiO₂ 500C and 10-12atm
for adding H₂O to ethene Phosphoric acid 300C 70 atm
For adding H₂ to ethene Ni 200C
Correct me if im wrong!

[8T]

YOu hvave to show that you know that the reaction ends at the 12 cm³ and the other i dont know i dont remember the question 8-)

Here's the link may june 09 5 b pleaaaaaase explain..
www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_3.pdf
P 32

[Vin]

Here's the link may june 09 5 b pleaaaaaase explain..
www.freeexampapers.us/IGCSE/Chemistry/CIE/2009%20Jun/0620_s09_qp_3.pdf
P 32

It;s been solved earlier, i need to look..