O Level 5072 Chemistry Aftermath Report

last SG · 2008-11-12T20:42:09+00:00

i minus 3. One is careless about the humber of H in ester. Fark man. I forgot to count the H at the end of the acid.another is keroseneanother one is the whi...

Garrick_3658 SG

Qn 11 also wrong, the water is a liquid, not a gas.

So you cannot compare the ratio of water. Answer should be A

Maybe you would like to look more properly?

[e].Le-V SG

You are the one that should look more properly. Lmao

davidche SG

hmm but according to your theory. B can also be the choice right? Cos A and B are too alike. SO i chose C

[e].Le-V SG

hmm but according to your theory. B can also be the choice right? Cos A and B are too alike. SO i chose C

A and B alike? Erm...

A : 6 moles to 3 moles = decrease 50%

B : 7 moles to 2 moles = decrease ~ 71%

C : 3 moles to 1 mole = decrease ~ 67%

A and B don't seem to alike, and answer is clearly A... smallest % change.

davidche SG

say 2 mol of liquid occupies one mole of gas, its almost the same. Moreover you cant be sure it is 2:1. I think need to ask the pros here bout the qn lar.

Craappiboy SG

lol what 2 mol of liquid occupy 1 mol of gas? what's this suppose to mean? post the qn

[e].Le-V SG

Volume of liquid and volume of gas are so much different!

1 mole of H20 gas occupies 24000 cm³

1 mole of H20 liquid = 18g = 18 cm³

so u cannot assume 2 moles of liquid occupies 1 mole of gas

Garrick_3658 SG

I already said, heck care the volumes of solids and liquids. 1 mole of gas already beat them hands down, 24000 cm^3 fight with ~~~100 cm^3.

Hmm, yes [e].Le-V, I just realised about the percentage. I was looking at the change in volume directly. Looks like one more mistake for me :P I guess this is why they made P2 so no kick. Thanks btw.

And btw, I was referring to you LOOK MORE CAREFULLY talking about water. WHEN I ALREADY SAID I DIDN'T COMPARE LIQUIDS.

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