IGCSE CHEMISTRY DOUBTS HERE !!!!

[Vin]

I hope I'm right.

1. Ce = 140g

n = 4.2/140
=0.03 moles

2. 5.16 - 4.2 = 0.96 g

3. moles of O2

n = 0.96/ (16+16)
= 0.03 moles

4. ratio = 1:1

5. Ce + O₂ ---> CeO₂

Formula = CeO₂

[~Dazzling Star~]

I hope I'm right.

1. Ce = 140g

n = 4.2/140
=0.03 moles

2. 5.16 - 4.2 = 0.96 g

3. moles of O2

n = 0.96/ (16+16)
= 0.03 moles

4. ratio = 1:1

5. Ce + O₂ ---> CeO₂

Formula = CeO₂

hmmmm,i think it should be done like this :
1 . n=m/Mr
     n=4.2/75
     n=0.056 moles
2 . mass of reacted Oxygen=5.96-4.2=0.96g
3 . n=m/Mr
     n=0.96/(16*2)=0.03 moles
4 . 0.056:0.03=2:1
5 . CeO
do u agree?

[Vin]

Hmm I think the Mr for Ce is 140g in the periodic table. :/ atomic number 58

[Most UniQue™]

M/j 2005 p62 Q8

Plz help got exam tomorrow Thanks in advance:D

[The Golden Girl =D]

can ya give me a link of the paper.

[Most UniQue™]

can ya give me a link of the paper.

http://www.freeexampapers.com/past_papers.php?l=Past_Papers%2FIGCSE%2FChemistry%2FCIE%2F2005+Jun/

[The Golden Girl =D]

M/j 2005 p62 Q8

Plz help got exam tomorrow Thanks in advance:D

I'll give you the General Idea behind it.

You put a known amount of hydrogen peroxide in a test tube  that is connected to a gas syringe and burn the test tube/allow the powder inside it to decompose ... for certain time intervals ex every 1 minute record the time and the volume of gas collected

the one the gave out the most gas in the same period of time is the best catalyst.

I hope I helped

[Most UniQue™]

I'll give you the General Idea behind it.

You put a known amount of hydrogen peroxide in a test tube  that is connected to a gas syringe and burn the test tube/allow the powder inside it to decompose ... for certain time intervals ex every 1 minute record the time and the volume of gas collected

the one the gave out the most gas in the same period of time is the best catalyst.

I hope I helped

Oh okaaa tnxxx!!!!

[Most UniQue™]

and By the way for the same paper,q6c, should i draw a chromatograph or explain?

[The Golden Girl =D]

and By the way for the same paper,q6c, should i draw a chromatograph or explain?

Explain but Whenever I had chromatography exps , My teacher used to say that we have to draw and explain.

[Most UniQue™]

Explain but Whenever I had chromatography exps , My teacher used to say that we have to draw and explain.

they havent given any lines for writing,they have just given a blank space so r u sure?

Yah in the other they give both line and blank space for both drawing and writing

[The Golden Girl =D]

I'm not sure .

[Most UniQue™]

I'm not sure .

ok By the way for the same question i should only show a drop of jam on the starting line and the spots which appear or i should also include 2 or 3 drops of other colours on the starting line also?

Thanks and sryt fr askign too many questions:D want to be sure:D:

[The Golden Girl =D]

ok By the way for the same question i should only show a drop of jam on the starting line and the spots which appear or i should also include 2 or 3 drops of other colours on the starting line also?

Thanks and sryt fr askign too many questions:D want to be sure:D:

It's  lemon drink ... Put a Drop at the starting line and a 2 drops since it's made of two colorings.

[Most UniQue™]

It's  lemon drink ... Put a Drop at the starting line and a 2 drops since it's made of two colorings.

ok got it:D