AS Chemistry P2 Prep.

[robotic94]

Anode: oxidation, since chloride ion reacted to form chlorine gas, oxidation number rises from -1 to 0.
Cathode: reduction, since hydrogen ion reacted to form hydrogen gas, oxidation number drops from +1 to 0.
And just a small hint: oxidation always happens at the anode and reduction at the cathode.

phew! I was right!
the markscheme scared me!

 

[DragonCub]

phew! I was right!
the markscheme scared me!

What does the MS say then?

 

[robotic94]

Anode: oxidation, since chloride ion reacted to form chlorine gas, oxidation number rises from -1 to 0.
Cathode: reduction, since hydrogen ion reacted to form hydrogen gas, oxidation number drops from +1 to 0.
And just a small hint: oxidation always happens at the anode and reduction at the cathode.

Oh btw tysm

 

[robotic94]

What does the MS say then?

the ms says (iii) anode Cl goes from -1 to 0 (1)
cathode H goes from -1 to 0 (1)

 

[JulyMei]

Thanks a lot littlecloud!

Just one question.



Are we supposed to take the specific heat capacity of water as 4.18 or 4.2? o-o; I always thought its supposed to be taken to 1 decimal place...

should use 4.18, unless the question ask u to use 4.2

 

[littlecloud11]

mmm
1)whats the advantage and disadavatages of fuel cells compared to combustion of hydrogen fuels ?

2)how reaction of esterification is carried out in a laboratory/school?

3)Eutrophication?

yea thats all

Anyone ?

1)Fuel cell-
Advantages: High efficiency conversion- converts chemical energy directly to electrical energy without the combustion process.
Quiet operation- due to their nature of operation, are extremely quiet in operation, thus reducing noise pollution
operates indefinitely as long as there is continuous supply of fuel
Does not pollute, as H20 is the only emission product.
Disadvantages: expensive.
Energy sources are extremely flammable
Operation requires replenish able fuel supply.


2) heat a mixture of alcohol and carboxylic acid with conc. H2SO4

3) excessive growth of algae/ water plants on the surface of water bodies due to leaching of fertilizers into lake, that causes plants at the bottom to die and be decomposed by bacteria that use up oxygen in the process. And this in turns leads to the death of aquatic animals.

 

[littlecloud11]

Thanks a lot littlecloud!

Just one question.



Are we supposed to take the specific heat capacity of water as 4.18 or 4.2? o-o; I always thought its supposed to be taken to 1 decimal place...

4.18 unless the question states otherwise.
4.18 is the value quoted in the data booklet.

 

[DragonCub]

the ms says (iii) anode Cl goes from -1 to 0 (1)
cathode H goes from -1 to 0 (1)

H goes from minus 1 to 0??? That's a huge mistake.

 

[Silent Hunter]

Is structure of DNPH in our syllabus?

 

[leosco1995]

Is structure of DNPH in our syllabus?

No, but you need to know its reaction with aldehydes/ketones.

 

[Silent Hunter]

The condensation one?

 

[Nibz]

The condensation one?

Yes, where Orange ppt. forms. You should be able to draw the structural (displayed) formula of the resulting product after its reaction with Aldehyde or Ketone.

 

[RGBM211]

mmm why does electrons enter 4s level before 3d level ?

 

[Gémeaux]

mmm why does electrons enter 4s level before 3d level ?

because the orbital s is at a lower energy level than d. 4s is filled first, *emptied* first.

 

[angelgirl:)]

explain y cracking is useful/?

 

[Hassi123]

Is structure of DNPH in our syllabus?

yes it is! its STRUCTURAL reaction with aldehyde and ketones has been asked so many times

 

[Hassi123]

explain y cracking is useful/?

it breaks large H-Cs into smaller more useful HCS. for example lets say c50h100 which isnt of much use is broken into many smaller hcs, lets say one is ch4 which is methane and is very useful

 

[Silent Hunter]

Yes, where Orange ppt. forms. You should be able to draw the structural (displayed) formula of the resulting product after its reaction with Aldehyde or Ketone.

Thanks alot

 

[angelgirl:)]

it breaks large H-Cs into smaller more useful HCS. for example lets say c50h100 which isnt of much use is broken into many smaller hcs, lets say one is ch4 which is methane and is very useful

is it ok if we write that introduction of alkane grp gives more reactive products

 

[Hassi123]

can someone explain hybridisation?