Chemistry Doubts: IGCSE Paper 3

[tribianni]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w09_qp_31.pdf Q6 c ASAP

 

[wooowooowoo]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w09_qp_31.pdf Q6 c ASAP

Moles, my love.
Ok
So moles of FeSO4 = 9.12 / 152 = 0.06
Fe2O3 moles formed = 0.06 / 2 = 0.03 (2:1 ratio)
16x3 = 48
56x2 = 112
112 + 48 = 160g


Mass of iron(x) oxide formed 0.03x160= 4.8g
Moles of SO3 = 0.03
Volume of sulphur = 0.03*24 = 0.72

Check with ms, since you said asap, i couldn't do it mself

 

[ThatReallyReallyWeirdDude]

I just spent the past half-hour solving a chemistry paper, and was like "WOW! This is super easy, I'm amazing at chemistry"
Obviously since I'm not amazing at chemistry I started to doubt this was even a paper, took a look down.. realize its paper 2..
Im going to go shoot myself, brb.

LOL I FEEL YOUR PAIN!
I remember opening an A Level past paper in curiosity
And being like...WOAH I CAN SOLVE HALF OF THIS!
Then i realized not only is it CORE but it's AS not A2 >.>
*monumental facepalm*

 

[Z.A.M]

Moles love of my life tooo

 

[ZainH]

LOL I FEEL YOUR PAIN!
I remember opening an A Level past paper in curiosity
And being like...WOAH I CAN SOLVE HALF OF THIS!
Then i realized not only is it CORE but it's AS not A2 >.>
*monumental facepalm*

LOL WHAT? You could solve half of an AS paper?!
Even if it's core that makes you a GENIUS. My case was worse >.<

 

[tribianni]

Moles, my love.
Ok
So moles of FeSO4 = 9.12 / 152 = 0.06
Fe2O3 moles formed = 0.06 / 2 = 0.03 (2:1 ratio)
16x3 = 48
56x2 = 112
112 + 48 = 160g


Mass of iron(x) oxide formed 0.03x160= 4.8g
Moles of SO3 = 0.03
Volume of sulphur = 0.03*24 = 0.72

Check with ms, since you said asap, i couldn't do it mself

kk thnxx diss toooo http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_qp_31.pdf Q8b

 

[wooowooowoo]

kk thnxx diss toooo http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w10_qp_31.pdf Q8b

Weirdude is here, he shall take care of it.
I thought it was an emergency so I answered.

 

[Z.A.M]

http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Chemistry (0620)/0620_w09_qp_31.pdf Q6 c ASAP

Since woowoooo as alredy solved ur question which i just did for u
I can give you these formula
n=m/Mr
where n=no. of moles
m=mass given for e;g 9.12 in the question
Mr= mass of 1 mole of the substance
For volume of gases
n=V/24 dm3
n=no of moles
V=volume u wana find out
Remember divde by 24 always in dm3 not cm3
Hope i helped

 

[wooowooowoo]

LOL I FEEL YOUR PAIN!
I remember opening an A Level past paper in curiosity
And being like...WOAH I CAN SOLVE HALF OF THIS!
Then i realized not only is it CORE but it's AS not A2 >.>
*monumental facepalm*

You smart smart smart kid. Send me the paper please? I wanna try solving it too, I'm too bored in life, really

 

[ThatReallyReallyWeirdDude]

You smart smart smart kid. Send me the paper please? I wanna try solving it too, I'm too bored in life, really

LOL It was back in December and unlike Taylor Swift I can't just go Back to December. :|

 

[Dsilentkila]

Alright the difference is that structural actually shows the positioning/structure of the atoms
Now the first thing you do when drawing structural formulas is draw the skeleton of carbon atoms.
For example lets say they tell you to draw pent-2-ene
We know three things as soon as they tell us pent-2-ene
a) It has a formula of C5H10
b) The double bond is located after the second carbon atom (hence the 2)
c) It has 5 carbon atoms
SO first thing you do is draw the carbon atoms since they form like the main structure
in this case it is:
C-C=C-C-C
Then you have to remember; carbon atoms can form four bonds, so you have to fill whatever bonds that are not filled!
The first carbon atom only has one bond, so add three hydrogens
The second carbon atom has three bonds, so add one hydrogen
The third carbon atom also has three bonds so add one hydrogen
The fourth carbon atom has 2 bonds so add two hydrogens.
The last carbon atom has 1 bond so add 3 hydrogens.

The end result is this:

View attachment 11052
In general you can apply this anywhere. If they said to draw 1,3 dichloropentane, you know there is 2 chlorines and that they are located on the first and third carbon atom. You have to understand what the numbers mean so you can put things such as hydroxyl groups, halogens and double bonds in the right place.

Wow man, thanks a heaven of a lot, thats some clear cut explanation.
anyways we do this when they say draw right, what if they say write the structural formual? this what should be written right? CH3-CH=CH-CH2-Ch3.
thanks again man

 

[ZainH]

Could someone with a few minutes to spare, post the SYMBOL equation for the reduction of Iron (III) oxide to iron.
Mark scheme just says "Correct equation" .. Need to make sure mine's correct x)

 

[Z.A.M]

Could someone with a few minutes to spare, post the SYMBOL equation for the reduction of Iron (III) oxide to iron.
Mark scheme just says "Correct equation" .. Need to make sure mine's correct x)

Fe2O3+3CO=2Fe+3CO2
Iron oxide + carbon mono oxide = iron+ carbon dioxide
If u have the book Chemistry for o level by Christopher Prescott there's whole description in there about various metals certify useful

 

[Penalopi]

By the way it doesn't.

It does! but it doesn't help alot.. all you need to know is how electrons flow from the negative terminal to the iron preventing it from ionising/ rusting

 

[ZainH]

Fe2O3+3CO=2Fe+3CO2
Iron oxide + carbon mono oxide = iron+ carbon dioxide
If u have the book Chemistry for o level by Christopher Prescott there's whole description in there about various metals certify useful

Thank you kind sir x)

 

[Penalopi]

Question: When fat is hydrolysed by boiling with NaOH what are the products?

 

[Jspake]

Can someone please explain hydrolysis.. i'm clueless.. and its use in fats, amino acids.. etc. Please reply! I'm eating my book to get the concept..

 

[ThatReallyReallyWeirdDude]

Question: When fat is hydrolysed by boiling with NaOH what are the products?

The product is sodium stearate (i.e. soap) and a complicated alcohol.

 

[Penalopi]

The product is sodium stearate (i.e. soap) and a complicated alcohol.

umm, is that complicated alcohol glycerol??

 

[Penalopi]

Can someone please explain hydrolysis.. i'm clueless.. and its use in fats, amino acids.. etc. Please reply! I'm eating my book to get the concept..

open this website: http://www.chemguide.co.uk/orgmenu.html <--- it helps