question thirteen (1 Viewer)

euphoric

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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

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

euphoric

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

persephone

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

stevenwong86

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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

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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

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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)
 

lukebennett

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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
 

Komaticom

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"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

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dammit C??

edit: now i noe what i did wrong. thankz smelly and managore
i totally forgot about the 1-propanol burnt.
argh
 
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Steven12

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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

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

KungPow

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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

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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

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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!!
 

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