kyzoo's Chem questions

[Martoman]

there'd be other losses of energy in the forms of light, noise, kinetic (knocking about inside the cell)

[kyzoo]

there'd be other losses of energy in the forms of light, noise, kinetic (knocking about inside the cell)

But then y is waste heat an invalid answer?

[kyzoo]

i need help for chem too:

*How do you know if the product from a chemical reaction is a salt from looking at the equation
*How do you determine if a precipitate is formed when two aqueous solutions are reacted together
*I dont get the concept that the more reactive metal will replace a less reactive metal ion in a solution
*2KCL + Ag2SO4 ---->  K2SO4 +2AGCL , if the precipitate in this reaction was filtered what would the compound of teh residue caught in filter paper? and what would be in the filtrate? 


ill karma you

1. Salt = Ionic compound

2. Umm...this was like Unit 2. You have this whole table of ions and whether they form soluble or insoluble compounds when combined with other ions. Hasn't really cropped in Unit 3/4 as much as I thought it would =/ I think it's mainly Ag+ ions will ppt with OH- ions.

3. I don't get the question

4. The filtrate is the stuff that is filtered out...I think X.X

[Martoman]

the last question of that lot is the AgCl its a solid. It will be caught i nthe filter paper

[samiira]

i need help for chem too:

*I dont get the concept that the more reactive metal will replace a less reactive metal ion in a solution

A more reactive metal will replace a less reactive metal in a compound.  If a more reactive metal is placed in a solution of an ionic compound of a less reactive metal, the more reactive metal will replace the less reactive metal (single replacement reaction), and the less reactive metal will precipitate out of solution...

i hope this makes sense:/

[Blakhitman]

ok another qusetion

VCAA 2008, the qusetion where it asks why the mass of methanol produced by the fuel clel is less than expected

Can I say "Assumption of previous part incorrect: Not all the current passing through the fuel cell is used to produce methanol" It wasn't oneo f the answers in the assessor's report, and I can't see anything ruling this answer out

That's pretty much what I said too lol. I thought it would be accepted :S

[Mao]

=/ Y is curent lost by haet wrong?

And this paper was really long =/

It said it in the paragraph underneath.  Doesn't apply to the context of this fuel cell or something.

And maybe it was sorta long, but very doable.  I don't mind if it goes ages as long as nothing stumps me haha...

I saw that too but i don't understand y it doesn't apply to the contxt of this fuel cell

Don't quote me on this, but I thought that fuel cells just go chemical > electrical energy, so they shouldn't produce heat.

=/ but its only 60-75%ish conversion arte from chemical to electrical, so there has to be waste heat

Yeah, but they are saying the ~30% loss is not due to heat, but because methanol reacted in a different reaction or evaporated.

We need Mao to clarify haha...

Nope, it'll be heat losses. There's always heat losses. Thermodynamics is a bitch, the minimum theoretical heat loss of a fuel cell is around 20%, add another ~10% on because of non-ideal conditions.

HEAT LOSSES. HEAT LOSSES, MORE HEAT LOSSES. When you learn about 'entropy', your'll understand why it's such a bitch.

[stonecold]

So jibbed on another mark cause that's what I said dammit.

bloody vcaa... nuff said.