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Chemistry P1 Challenging Questions Preparation

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fishcook

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1ajia1 said:
density =mass/ volume so density/ mass is 1/ volume
2 is wrong because PV=moles ( n ) RT and while the option is PV=M(molar mass)RT
Click to expand...
Thank you so much.
One more thing are their any other formulas behind like kc kp formulas for moles that we should know?
 
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1ajia1

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white rose said:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_qp_11.pdf
can anyone explain me q.10, 15 & 23...ur help is highly appreciated..
Click to expand...
q10: the equation is C2+3H2 --->C2H6
Using the hess cycle 2(enthalpy change of combustion of carbon) +3(-286)- (-1560)= -158
solve it and you will get the answer :)
Q15 : assuming the element as X, the equation will be X(NO3)2---> XO +2 NO2 + 0.5O2
moles of the nitrate equals the mole of the oxide formed
2/(X+ 14*2 +16*6) = (2-1.32)/(X+16)
solve for X and then match the Mr in the periodic table to find the element.
Q23: D is wrong because odd number wont give hydrocarbons with equal number of carbon atoms
A and B if n is 4 and 6 respectively then the carbon number in the hydrocarbons will be 2 and 3 (these cant have isomers)
The correct option is C because 8/2 will give you 4 and you can make chained isomers from hydrocarbons with 4 atoms
Hope that helps :)
 
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1ajia1

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fishcook said:
Thank you so much.
One more thing are their any other formulas behind like kc kp formulas for moles that we should know?
Click to expand...

Anytime :) and what do you mean by other formulas for moles?
Kp and Kc are for equllibrium calculations
 
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fishcook

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1ajia1 said:
Anytime :) and what do you mean by other formulas for moles?
Kp and Kc are for equllibrium calculations
Click to expand...
Sorry I actually meant like other formulas that we haven't done in chemistry. Other than kp kc calculations and the formulas for moles.
Like the density equation and others like that? If there are any
 
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1ajia1

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fishcook said:
Sorry I actually meant like other formulas that we haven't done in chemistry. Other than kp kc calculations and the formulas for moles.
Like the density equation and others like that? If there are any
Click to expand...
They are just basic ones like density =mass/ volume , concentration=moles/volume, moles=Mass/Mr, Volume of gas= Moles * 24
 
white rose

white rose

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1ajia1 said:
IN
q10: the equation is C2+3H2 --->C2H6
Using the hess cycle 2(enthalpy change of combustion of carbon) +3(-286)- (-1560)= -158
solve it and you will get the answer :)
Q15 : assuming the element as X, the equation will be X(NO3)2---> XO +2 NO2 + 0.5O2
moles of the nitrate equals the mole of the oxide formed
2/(X+ 14*2 +16*6) = (2-1.32)/(X+16)
solve for X and then match the Mr in the periodic table to find the element.
Q23: D is wrong because odd number wont give hydrocarbons with equal number of carbon atoms
A and B if n is 4 and 6 respectively then the carbon number in the hydrocarbons will be 2 and 3 (these cant have isomers)
The correct option is C because 8/2 will give you 4 and you can make chained isomers from hydrocarbons with 4 atoms
Hope that helps :)
Click to expand...
thanks a lot...but i m nt getting the ans for q.10...cud u please show me the calculations...
 
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1ajia1

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