FAQ ; Chemical cell

SPM Frequently Ask Question :

TOPIC : ELECTROCHEMISTRY

CHEMICAL CELL

Structure question : You should study  these

• 1.       The function of  Salt bridge  and Porous Pot

• 2.       Energy changes in cell

• 3.       State/write all the  ions presence in electrolyte

• 4.       Which electrode will act as anode/ cathode or negative terminal/ positive terminal ( must based on Electrochemical series)

• 5.       Write half equation at anode and cathode

• 6.       State the colour change of electrolyte

• 7.       State the observation at electrode

• 8.       Show the direction of electron flow at connecting wire

 

Eg :

 

         Diagram 3 shows the set-up of apparatus of a chemical cell.

Rajah 3 menunjukkan susunan radas sebuah sel kimia.

(a)                What is the function of the porous pot?

Apakah fungsi pasu berliang?

to allow the movement/flow of the ions.                                                            [1 mark]

(b)               What is the energy change that occurs in the cell?

Apakah perubahan tenaga yang berlaku dalam sel itu?

Chemical Energy to electrical Energy                                                                  [1 mark]

(c)                Write the formula all ions present in the Copper(II) sulphate solution?

Tuliskan formula semua ion-ion yang terdapat dalam larutan kuprum(II) sulfat?

Cu²⁺ ,  SO₄^2- , H⁺ and OH^-                                                                 [1 mark]

(a)                State which metal plate acts as the

Nyatakan kepingan yang mana bertindak sebagai

negative terminal :

terminal negatif :

Zinc Plate *

positive terminal :

terminal positif :

                                Copper Plate   *

* mesti merujuk siri elektrokimia ; Logam yang berada di atas dalam siri elektrokimia bertindak sebagai terminal negative, manakala logam yang terletak di bawah bertindak sebagai terminal positif

 [1 mark]

(d)         Write the half equation of the reaction at the

Tuliskan persamaan setengah bagi tindak balas di

negative terminal :

terminal negatif :

                                Zn     →      Zn²⁺        +        2e

[1 mark]

positive terminal :

terminal positif :

Cu²⁺       +       2e     →    Cu

[1 mark]

(e)          What is the colour change of the copper (II) sulphate solution? Explain your answer.

Apakah perubahan warna yang berlaku kepada larutan kuprum(II) sulfat? Terangkan jawapan anda.

                         *Blue to colourless / becomes fade / paler

The number of copper(II) ions decrease //The concentration of copper(II) ions decrease

[2 marks]

* copper(II) sulphate colour is blue  - you must remember this

(f)           What will be observed at copper plate?

Apa yang diperhatikan pada kepingan kuprum ?

                plate becomes thicker / kepingan kuprum menebal

(g)          Draw arrows indicating the flow of electrons in Diagram 3.

                Lukis anak panah yang menunjukkan pergerakan elektron pada Rajah 3.

                As shown as in diagrams

[1 mark]