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ALL CIE CHEMISTRY DOUBTS HERE !!
Deadly_king:
--- Quote from: moon on November 13, 2010, 04:25:56 pm ---pls I need help in Nov.06 Q9, 11 12 31, 32.
thanks for ur help. :) :)
--- End quote ---
Nov 06 p1
9. Reaction : CO2(g) + H2(g) -----> CO(g) + H2O(g)
So we are converting CO2 to CO while H2 is being oxidised to H2O. However both H2 and H2O are in gaseous state. ;)
Conversion of CO to CO2 is given as -283 KJmol-1. Since we're converting CO2 to CO, it will be +283 KJmol-1.
Converting H2 to water in liquid is given -286 KJmol-1. But we have to convert it back to gaseous state, hence net energy will be (-286 + 44) = -242 KJmol-1
Hence Change in enthalpy of reaction : (+283 - 242) = +41 KJmol-1
Answer turns out to be C
11. For the reaction Kc = [CH3CO2C2H5][H2O] / [C2H5OH][CH3CO2H]
Since from the reaction mole ratio is 1:1 for every reactant and products, it becomes easier.
[C2H5OH] [CH3CO2H] [CH3CO2C2H5] [H2O]
Initially 1.0 1.0 0.0 0.0
At equilibrium 1- 1-
Therefore Kc = ()() / (1-)(1-) = 4
It also implies [/(1-)]2 = 4
Now you simplify and you'll get = 2/3
Hence number of moles of ethyl ethanoate formed is 2/3
Answer is B
12. At low temperature, less molecules will have have reached activation energy to undergo the reaction. Hence the graph with lower peak is to be used.
Energy of such a graph is found on the x-axis. ;)
Hence answer is D
31. The chlorine oxide radical is ClO..
It is made up of a covalent bond between the Cl and O atom. Since the oxygen atom carries only one bond, it has one more free electron available for bonding.
Hence the oxygen atom contains an odd number of electrons. However no dative bond is present in this molecule.
Hence answer is B
32. Strong acid imply that it dissociates rapidly to form the corresponding ions while a weak acid does not dissociate much.
Hence sulfuric acid is a strong one which implies it will form much H+ and HSO4-. The latter being a weak acid will not dissociate much such that SO4- will only be present in minimal amount. ;)
Answer is D.
haris94:
state 2 reasons why noble gases behave less ideally as you go down the group 8?
pls explain
thanx
Deadly_king:
--- Quote from: haris94 on November 14, 2010, 02:14:50 pm ---state 2 reasons why noble gases behave less ideally as you go down the group 8?
pls explain
thanx
--- End quote ---
1. As you go down the group, the atoms increase in size such that their volume become large enough. Hence their volume are no more negligible. ;)
2. As you go down the group the atoms of the noble gases become larger due to increase in number of shells. Hence the outermost electron is further away from the nucleus. Therefore the force of attraction decreases such that it is easier to remove an electron from it. It becomes less stable and it is easier to form attraction.
--- Quote from: http://www.glencove.k12.ny.us/highschool/ChemRev/ChemRev.html ---Ideal gases [How gases should behave but don’t]-
1. No attraction between molecules/atoms
2. Molecules have a negligible volume
3. Collisions are elastic
4. Particle movement is random
Real gases VERY RARELY BEHAVE LIKE IDEAL GASES since
1. There IS an attraction between particle (van der Waals)
2. The volume of particles are NOT negligible, esp. at low temps & high-pressure since atoms/molecules are close together
***HYDROGEN and HELIUM are the most IDEAL gases.*** Also, Diatomic molecules and nonsymmetrical molecules & noble gases act the most ideal. THE SMALLER THEY ARE THE MORE IDEAL THEY BEHAVE.
--- End quote ---
Hope it help :)
birchy33:
10. At a total pressure of 1.0 atm, dinitrogen tetraoxide is 50% dissociated at a temperature of 60 C,
according to the following equation.
N2O4 2NO2
What is the value of the equilibrium constant, Kp, for this reaction at 60oC?
A 1/3 atm
B 2/3 atm
C 4/3 atm
D 2 atm
Please explain. Its from MJ/06 P1 thank-you. Oh and please can you held with 18 and 20 from the same exam.
moon:
pls can u help in Nov.08 Q3,30,39 and Nov. 09 Varient 1 Q5,21,22,28,29,31. Thanx in advance.
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