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chemistry CIE past ppr doubt

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Sue T:
november 2003 (ppr2)
in question 3(bii)they ask us 2 calculate th heat released
n they gave th temp change as 12.2°C
now i used e=mc?t
n  ?t should be in kelvin, so ?t=(12.2 + 273) K
but in the ms, they jus kept it as 12.2 !
why? >:(
& (d) also - i don get it

nid404:
3b(ii)

In case of water
The specific heat capacity of water is:
o cwater = 1 cal/(g°C) = 1 cal/(g?K)
o cwater = 4.184 J/(g°C) = 4.184 J/(g?K)
o cwater = 4184 J/(kg°C) = 4184 J/(kg?K)

So u shouldn't change the rise in temp to Kelvin...A change in temperature of 12.2
oC is of the same magnitude as a change in temperature of 12.2 K.


For the (d) bit of it
The reaction is Ca+ 2H2O---> Ca(OH)2+ H2
1 mole=40g of Ca give 24dm3 of H2(1 mole of H2...1 mole of any gas at rtp is 24dm3)
therefore 1g of Ca will give 24/40dm3 of hydrogen 0.6dm3 or 600cm3

Hope u've got it

Sue T:
got it! thank you so much! ;D

nid404:

--- Quote from: Sue T on December 24, 2009, 09:58:23 am ---got it! thank you so much! ;D

--- End quote ---

ur welcome :)

sweetie:
can any1 help me in solving que.6 paper1 ( AS chem.)????

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