Chemistry: Post your doubts here!

[Thought blocker]

10.When solid ammonium chloride dissociates at a certain temperature in a 0.500 dm3 container,
ammonia and hydrogen chloride are formed.
NH4Cl (s) NH3(g) + HCl (g)
The initial amount of ammonium chloride was 1.00 mol, and when the system had reached
equilibrium there was 0.300 mol of ammonium chloride.
What is the numerical value of Kc for this reaction under these conditions?
A 0.490 B 1.63 C 1.96 D 3.27
ans is C But how do we get that?

Makee that initial, change and equilibrium moles table and do it.

 

[drowning-in-studies]

24 Oct-1-ene, CH3(CH2)5CH=CH2, is subjected to thermal cracking.
Which combination of compounds W, X, Y and Z can be obtained?
CH2=CH2 CH3CH=CH2 CH3CH2CH3 CH2=CHCH=CH2
W X Y Z
A W, X, Y and Z
B W, X and Z only
C W, X and Z only
D W and X only
Ans is A But how can there be more carbon atoms after thermal cracking?

 

[Cadence]

Anyone help me to solve this question thx~~~
Total removal of the pollutant So2 is difficult both for economic and technical reasons. the quantities emitted from furnace chimneys can be lowered by using desulfurization plants. The gases are scrubbed with Ca(oH)2 to removes so2. what is the main product formed initially?
9701/11/O/11 ques 18

 

[Thought blocker]

24 Oct-1-ene, CH3(CH2)5CH=CH2, is subjected to thermal cracking.
Which combination of compounds W, X, Y and Z can be obtained?
CH2=CH2 CH3CH=CH2 CH3CH2CH3 CH2=CHCH=CH2
W X Y Z
A W, X, Y and Z
B W, X and Z only
C W, X and Z only
D W and X only
Ans is A But how can there be more carbon atoms after thermal cracking?

Anyone help me to solve this question thx~~~
Total removal of the pollutant So2 is difficult both for economic and technical reasons. the quantities emitted from furnace chimneys can be lowered by using desulfurization plants. The gases are scrubbed with Ca(oH)2 to removes so2. what is the main product formed initially?
9701/11/O/11 ques 18

You guys check out that channel on youtube of metatutor.

 

[Adarsha Shrestha]

Did you get the answer?

 

[Adarsha Shrestha]

2 Equations involving four enthalpy changes are shown.

Na(g) → Na+(g) + e– Na(g) → Na2+(g) + 2e– Na(s) → Na(g)
Na(s) → Na2+(g) + 2e–

∆H= W ∆H = X ∆H = Y ∆H = Z

What is the second ionisation energy of sodium?A 2W B X – W C Y – W D Z – Y
help(

did you get the answer?

 

[Cadence]

did you get the answer?

The Ans is B

 

[Cadence]

Which halogenoalkane produces the highest percentage of product by an SN1 mechanism, when treated with Naoh (aq)
A 2-bromopropane
B 2-chloroprapane
C 1-iodo-2-methylpropane
D 2-iodo-2methylpropane

 

[Thought blocker]

Which halogenoalkane produces the highest percentage of product by an SN1 mechanism, when treated with Naoh (aq)
A 2-bromopropane
B 2-chloroprapane
C 1-iodo-2-methylpropane
D 2-iodo-2methylpropane

which year?

 

[Cadence]

which year?

9701/13/o/13

 

[Thought blocker]

9701/13/o/13

 

[Cadence]

Thank you!!

 

[Cadence]

Anyone pls explain 9701/11/m/14 ques 8 and 9

 

[Thought blocker]

Anyone pls explain 9701/11/m/14 ques 8 and 9

did u searched it on that channel?

 

[drowning-in-studies]

6 A white powder is known to be a mixture of magnesium oxide and aluminium oxide.
100 cm3 of 2 mol dm–3 NaOH(aq) is just sufficient to cause the aluminium oxide in x grams of the
mixture to dissolve.
The reaction occurring is Al 2O3 + 2OH– + 3H2O → 2Al (OH)4-
800 cm3 of 2 mol dm–3 HCl (aq) is just sufficient to cause all of the oxide in x grams of the mixture
to dissolve.
The reactions occurring are Al 2O3 + 6H+ → 2Al3+ + 3H2O
and MgO + 2H+ → Mg2+ + H2O.
How many moles of each oxide are present in x grams of the mixture?

aluminium magnesium
oxide oxide
A 0.05 0.25
B 0.05 0.50
C 0.10 0.25
D 0.10 0.50
How do you do this?
Ans D

 

[madridtas_CR7]

I am taking both AS level and A2, my major problems are with the practical papers. I am retaking chemistry AS level this year, along with the A2. Last year I scored 2 A's in my theory papers and a U grade on my practical paper. Have you got any suggestions on how I study both P3 and P5?

Work Hard and Believe in your seolf

 

[drowning-in-studies]

26 High-energy radiation in the stratosphere produces free-radicals from chlorofluoroalkanes,
commonly known as CFCs.
Which free-radical is most likely to result from the irradiation of CHFCl CF2Cl ?
A CHFClC*FCl
B *CHClCF2Cl
C *CHFCF2Cl
D *CFClCF2Cl
Ans is C. I don't understand the theory Why isn't it B or D?

 

[Cadence]

26 High-energy radiation in the stratosphere produces free-radicals from chlorofluoroalkanes,
commonly known as CFCs.
Which free-radical is most likely to result from the irradiation of CHFCl CF2Cl ?
A CHFClC*FCl
B *CHClCF2Cl
C *CHFCF2Cl
D *CFClCF2Cl
Ans is C. I don't understand the theory Why isn't it B or D?

Someone solved this ques tho
u can check the previous page
The ans is C because C-Cl bond is broken.

 

[Cadence]

6 A white powder is known to be a mixture of magnesium oxide and aluminium oxide.
100 cm3 of 2 mol dm–3 NaOH(aq) is just sufficient to cause the aluminium oxide in x grams of the
mixture to dissolve.
The reaction occurring is Al 2O3 + 2OH– + 3H2O → 2Al (OH)4-
800 cm3 of 2 mol dm–3 HCl (aq) is just sufficient to cause all of the oxide in x grams of the mixture
to dissolve.
The reactions occurring are Al 2O3 + 6H+ → 2Al3+ + 3H2O
and MgO + 2H+ → Mg2+ + H2O.
How many moles of each oxide are present in x grams of the mixture?

aluminium magnesium
oxide oxide
A 0.05 0.25
B 0.05 0.50
C 0.10 0.25
D 0.10 0.50
How do you do this?
Ans D

First u know n(NaOH)=0.2mol, so n(Al2O3) will be 0.1mol, The total n(HCL)=1.6mol
since n(Al2O3)=0.1mol, n(HCL) used to dissolve AL2O3 is 0.6mol, n(HCL) left to dissolve Mgo is 1.6-0.6=1mol, so n(MgO) will be0.5mol

 

[Cadence]

did u searched it on that channel?

yea i did but i can't find any paper for the year 2014
btw thx for the notes below