Qualification > Queries

ANY DOUBTS HERE!!!

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nid404:
be a lil more specific
or do u want the whole q to be done?

ruby92:
b ii,iii
cii and d

nid404:
b)ii)H=mcdt
=200x4.2X12.2=10.25KJ

iii) 1g gives out 10.25 KJ
    1 mole=??
1 mole of calcium=40.1g
so H released with 40.1g=40.1X10.25=- 411KJ/mol  exothermix(heat released)

c)ii) Ca(s) + 2H2O(l) ? Ca(OH)2(aq) + H2(g) ?H = –411
dh of formation of water= -286kJ/mol  since 2 moles of water =2X-286= -  572
dh reaction= h of products-h of reactants
      -411  = X- (-572)
       X= -411-572=-983KJ/mol

d) In b(ii) 1g of Ca ws used...1g of ca= 1/40.1 moles=0.025moles
   Ratio of Ca:H2=1:1
therefore 0.025 moles of H2 formed
1 moles occupies 24dm3
0.025mol=0.025X24=0.6dm3/ 600cm3

sweetie:

--- Quote from: notty_me on April 07, 2010, 07:11:32 pm ---more chemistry doubts..

cud u plz help me in  Q.30> the ms says 'A' but why is it not ethanol?
                            Q.20> ms says "c"
                            Q.2>   ms says ' B'

plzzzzzzzz, sum1 answer my que's >:(
--- End quote ---

nid404:
Please be patient....y r u getting furious..
We all have to study here....some1 will always answer when free

2) 30% x= 144
x=144X100/30=480g

P2=32X2=64g
% of P2= 64/480 X100
=13.1%

20) U have to try out all the possible outcomes with 4 carbons
You get 5 possibilities....try it

30) Ethanol will not react with NaOH at all....
Ethanol will only react with metals, not metal compounds..keep that in mind

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