question thirteen (1 Viewer)

[euphoric]

i dont get it.
i spent like 5mins trying to solve this question.
none. of my answers matched the multiple choices.
how did you people do it???

 

[VVoody]

I didn't get it either, but I guessed (I think C) and apparently I got it right

 

[euphoric]

C????? dammits.
i guessed A ><
im so gonna fail chemistry.
it was sooo different to last years paper ><

 

[persephone]

i got C. i just substituted all of them until i found something that vaguely resembled the number they had

 

[stevenwong86]

I put (C)

I found the molecular mass of propanol, then the moles of propanol burnt, then the heat given off. Then just plug the numbers into q=mct to find t.

 

[smelly]

I got C...I think it's right...but then u never know
0.60g propanol = 0.01 moles
.: heat released by propanol = 2021 x 0.01 = 20.21 kJ = 20210 J
Use that heat formula
H = mct
20210 = 200 (mass of water) x 4.18 x t
.: t = 24.17... (24.2)
but t is the change in temperature so u add that to the initial temperature
24.2 + 21 = 45.2

 

[Managore]

I ended up with C.

the 0.6 grams of prop used and 60 molar mass, and the 10^3 following the 4.18 I ignored, I did:

2012 (or whatever) / 4.18 x 200

which gave 24.2 approx, which I added to 21 to get 45 (cant remember exact figures)

 

[euphoric]

wow. lots of C ><

 

[lukebennett]

i was a fool. i did the mass of the propanol and forgot to change to joules. other questions were good except for 3. we only ever learnt Ca and Ba flame tests

 

[greentree]

me and krina both guessed c, cos if in doubt, its usually c isn't it??

 

[Komaticom]

"Who needs time to write their Student Number and Centre Number on your papers? Okay you got 5 minutes."

(Komaticom spots the 4 blank circles for Q 13. Stealthily blobs in answer C.)

W00t!

 

[euphoric]

dammit C??

edit: now i noe what i did wrong. thankz smelly and managore
i totally forgot about the 1-propanol burnt.
argh

 

[Scanorama]

I put down C, this damn question took me 7 minutes to get it/

 

[The Bograt]

I did some calculations and got 2.42 so i figured it looked like 24.2, so I added that and got C!

 

[petayani]

Oops. I put A cos I forgot there was only 0.6g of propanol. Noooo! Reading the question wrong is one of my strong points.

 

[Steven12]

I cant believe this, i told myself before the exam(REEEEEEEEEEEAD the bloody question) . worked the answer but didnt add it to the original temp, idiotttttttttttttttttttttttttttttt

 

[euphoric]

lolz yeah same with me!!
i always miss-read questions ><

 

[KungPow]

Was the answer really C? Damn my calculations were nowhere near, so i thought "Gee, I think I'll guess C. I haven't had a C in a while"

Let's hope it works out!

 

[sub]

C was the closest....i tried working it out and it didn;t work...i ended up with like 60sumfink °'s for the anser, so then i started using the answers given to work it out...C was the closest...i think off by like 20ish kJ?

 

[wind]

Damn it!

I got the answer except I forgot to add it 21.0 degress to get 45.2 degrees! Argghhh!!

I stuck in 24.2 degress instead So stupid!!