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Physics Paper 2, MAy/June. 2009  
Questions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Main
General Comments
Weakness/Remedies
Strength



























Question 6

    • State Faraday’s second law of electrolysis.
    • An electric charge of 9.6 x 104 C liberates 1 mole of substance containing 6.0 x 1023 atoms.  Determine the value of the electronic charge.


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Observation

In part (a), many candidates were able to state the law correctly.  Candidates’ performance in part (b) was poor due to lack of knowledge of the appropriate formula.

The expected answers are as follows:

(a) If the same quantity of electricity is passed through different  voltameters/electrolytes connected in series the masses of the substances liberated/deposited during electrolysis is (directly) proportional to their chemical equivalents.                                                                                        
OR The mass of an element deposited/liberated during electrolysis is (directly) proportional to the chemical equivalent of the element.

 

 

(b)        Let e represent the electronic charge.
                       
                        e  =   Faraday’s constant
                                 Avogadro’s number                                                                              

                        =          9.6 x 104                                                                                                                            
                                    6. 0. x 1023

=  1.60 x 10-19C                                  

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