Thursday, October 2, 2008

Practical assessment of STPM Chemistry

Check out the experiment! Will be updated from time to time....


Experiment 6 (Thermochemistry)

Purpose: to determine the hear of neutralisation of a strong acid with a strong base

Questions: c) heat released of each of the experiment, q = m x c x change of T = (10 + 30) x 4.2 x change of T

d) no. of moles of sollutions can be found by n = MV/1000

e) Ionic equations: H+ + OH- --H2O

f) Heat of neutralisation: H = c)/ d)

g) acid W is a diprotic acid h) - Mixture of solution must be sitrred through out the exp. - solutions must be mixed quickly to attain the maximum change of temperature.


Experiment 12 Question Answer provided served as reference,


e) From the graph of EO against lg [Zn2+], the value of Eo increases as the value of lg [Zn2+] decreases. Therefore the e.m.f. of the cell increases when the concentration of Zn2+ ions decreases.

f) (i) with reference of Nernst Equation, 0.059 [Zn2+] Ecell = EØcell + n lg [Cu2+] The value of lg [Zn2+]/[Cu2+] increases when the concentration of Cu2+ ions decreases. Hence the e.m.f. value decreases with the decrease in Cu2+ ions.

(ii) The Eo value for Al is larger than the Eocell value for zinc. Hence with the reference to the Nernst Equation, the Eocell value will be larger/

7 comments:

夕阳 said...
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winky said...
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winky said...

thx a lot guru! u helped me a lot.. as my teacher is quite fierce and we cant ask any question if we have any doubt or we don't know how to solve it so my class didn't manage to hand in the report on time twice and we got zero for that 2 experiments. hope u can post more experiment reports especially those hard ones.. THANK YOU!!

委纹 said...
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abdul wahab said...

nice Chemistry Exepriments

abdul wahab said...

nice Chemistry Exepriments

Chua Seng said...

THANK YOU!!!!!