O-Level Chemistry

[uptas]

achun708\" post_id=\"1967260\" time=\"1584339352\" user_id=\"184516:

Hello Everyone,

Can you please help me with this? My son is a bit confused with this problem and me too. Thanks.

Predict the products formed (i) at the cathode, (II) at the anode, when copper (II) sulfate solution is electrolysed using carbon electrodes.

Hello achun. The ANSWER to this problem is below.

Ions present:

From copper (II) sulfate: Cu2+ ions and SO4 2- ions

From water: H+ ions and OH- ions.


(i)

At cathode, Cu2+ and H+ ions are present.

Cu2+ ions are selectively discharged to form copper metal.

Cu2+ (aq) + 2e- will produce Cu (s)




(ii)

At anode, OH- and SO4 2- ions are present.

OH- ions are selectively discharged to form oxygen gas.

4OH- (aq) will produce 2H2O (l) + O2 (g)+ 4e-


Thanks!

[uptas]

Important Notes Related to Speed of Reaction:


1. The speed of reaction is the amount of reactant used up or the amount of product obtained per unit time.

2. Activation energy is the minimum energy that the reacting particles must possess for a reaction to occur.

3. An effective collision is a collision that is successful in producing a chemical reaction.

4. A catalyst is a substance that increases the speed of a chemical reaction.

5. An enzyme is a substance that catalyses biochemical reactions (chemical reactions in plants and animals).

[uptas]

Factors Affecting Speed of Reaction


1. The smaller the particle size

* the larger is the total surface area exposed to collisions
*the higher is the frequency of effective collisions
*the greater is the speed of reaction


2. The higher the concentration of the reactant

*the greater is the number of particles per unit volume
*the higher is the frequency of effective collisions
*the greater is the speed of reaction.


3. The higher the pressure of gaseous reactants

*the smaller is the volume
*the greater is the number of particles per unit volume
*the higher is the frequency of effective collisions
*the greater is the reaction.

Pressure has no effect on reaction that do not involve gases.


4. At higher temperature

*the reactant particles absorb energy and move faster
*more reactant particles have the minimum activation energy to react
*the number of effective collisions increases
*the greater is the speed of reaction.


5. Presence of Catalyst or Enzyme

*a catalyst provides an alternative route that requires a lower activation energy
*more reactant particles can overcome the lower activation energy
*this increases the frequency of effective collisions and hence the speed of reaction increases

[uptas]

Hello there!

Let's learn Organic Chemistry!

1st PART:
https://postimg.cc/MvDMVmjH

[chemanywhere15]

Learning Organic Chemistry


Part 2:


https://postimg.cc/QBp0JqrC

[chaocheng12]

chemanywhere15\" post_id=\"1973203\" time=\"1588129315\" user_id=\"185208:

Learning Organic Chemistry

Part 2:


https://postimg.cc/QBp0JqrC

Hello,

You are talking about homologous series. Is it correct to say that organic compounds with the same molecular formula does not necessarily belong to the same homologous series?

[chemanywhere15]

Hi chaocheng,


Yes, you are precisely right. This is a good point to remember since many commits error because of this.

An example is the molecular formula C2H4O2. This can be ethanoic acid or methyl methanoate. These two compounds belong to different homologous series carboxylic acid and ester.

[ANWI]

Hi All,

I m looking for O-level past year paper pdf for physics Chemistry and Biology.
Any suggestions?

[xinxin]

Hi can anyone help with this? Tks


https://postimg.cc/HjW3nFBH

[uptas]

xinxin\" post_id=\"1973998\" time=\"1588606213\" user_id=\"13771:

Hi can anyone help with this? Tks

https://postimg.cc/HjW3nFBH

Can check this solution out.
https://postimg.cc/0MRKBfjC