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प्रश्न
Explain electrolysis of lead bromide.
उत्तर
A steel rod is connected to the negative terminal and a graphite rod to positive terminal of a battery. A silica crucible is filled to about two thirds with solid lead bromide and the rods are dipped into into it and is then melted by heating it over a Bunsen burner.
Lead bromide contains :
PbBr2 ⇌ Pb+2 + 2Br-
Reaction at cathode : Lead ions are positively charged they get discharged at cathode. It receives two electrons from cathode and changes to atom of lead and get deposited at the cathode.
Pb+2 + 2e- → Pb
Reaction at the anode : Bromide ions, being negatively charged discharge at anode. It loses its only elctron and becomes an atom of bromine. Thus the atoms of bromine combine in pairs to form molecules of bromine which escape as red vapours, at the anode.
Br- + e- → Br
Br + Br → Br2
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संबंधित प्रश्न
Give reason for the following:
Lead bromide undergoes electrolytic dissociation in the molten state but is a non-electrolyte in the solid state.
Write down the word or phrase from the bracket that will correctly fill in the blank in the following sentence:
Pure water consists entirely of ________________ (ions/ molecules).
(a) Copy and complete the following table, which refers to two practical applications of electrolysis.
| Anode | Electrolyte | Cathode | |
| (i) Silver plating of a spoon | A solution of potassium argentocyanide | ||
| (ii) Purification of copper | |||
| (iii) Extraction of sodium |
(b) Write the equation taking place at the anode for Q. (a).
Fill in the black.
The metal plate through which ____________ leaves from an electrolyte is called ____________ .It has ______________ of electrons.
How electrolysis can be used in extraction of aluminium? Why aluminium cannot be reduced by conventional reducing agents?
Define or explain the term: Electrolysis.
Give one example of a substance which contain :
both ions and molecules.
Choosing only words from the following list, write down the appropriate words to fill in the blanks (a) to (e) below:
anions, anode, cathode, cations, electrode, electrolyte, nickel, voltameter.
To electroplate an article with nickel requires an (a) ________ which must be a solution containing (b) ________ions. The article to be plated is placed as the (c) _________of the cell in which the plating is carried out. The (d)________ of the cell is made from pure nickel. The ions that are attracted to the negative electrode and discharged are called (e)________.
Name the gas released at the cathode when acidulated water is electrolyzed.
Identify the following reactions as either oxidation or reduction : K - e- → K+
