Question

⤵⤵Question⤵⤵

Mention the drawback of Leclanche Cell.

Thanks❤​

Answer 1

$\huge\underline\mathfrak\red{Hello\:Mate}$

$\huge\boxed{\fcolorbox{blue}{white}{Answer}}$

_____________⤵⤵⤵⤵___________

✍️These are the shortcomings of leclanche dry cells

✒️Propensity to leak✒️⤵⤵⤵⤵

✍️The basic zinc carbon battery has a lower energy density than the competing alkaline batteries

⤵⤵⤵⤵

✍️Poor low temperature performance. Do not function well in sub-zero temperatures.

⤵⤵⤵⤵

✍️The use of naturally occurring manganese dioxide from different sources can lead to wide performance variations due to the presence of small quantities of impurities such as nickel, copper, arsenic, and cobalt.

______________________________________

$<b><marquee behavior= "alternate">PLEASE FOLLOW ME ✋:</marquee>$

Answer 2

Answer:

The Leclanché cell is a battery invented and patented by the French scientist Georges Leclanché in 1866.The battery contained a conducting solution (electrolyte) of ammonium chloride, a cathode (positive terminal) of carbon, a depolarizer of manganese dioxide (oxidizer), and an anode (negative terminal) of zinc (reductant).The chemistry of this cell was later successfully adapted to manufacture a dry cell.

The redox reaction in a Leclanché cell involves the two following half-reactions:

– anode (oxidation of Zn): Zn → Zn2+ + 2e−

– cathode (reduction of Mn(IV)): 2 MnO2 + 2NH4+ + 2e− → 2 MnO(OH) + 2 NH3

The chemical process which produces electricity in a Leclanché cell begins when zinc atoms on the surface of the anode oxidize, i.e. they give up both their valence electrons to become positively charged Zn2+ ions. As the Zn2+ ions move away from the anode, leaving their electrons on its surface, the anode becomes more negatively charged than the cathode. When the cell is connected in an external electrical circuit, the excess electrons on the zinc anode flow through the circuit to the carbon rod, the movement of electrons forming an electric current.

After passing through the whole circuit, when the electrons enter the cathode (carbon rod), they combine with manganese dioxide (MnO2) and water (H2O), which react with each other to produce manganese oxide (Mn2O3) and negatively charged hydroxide ions. This is accompanied by a secondary acid-base reaction in which the hydroxide ions (OH–) accept a proton (H+) from the ammonium ions present in the ammonium chloride electrolyte to produce molecules of ammonia and water.

Zn(s) + 2 MnO2(s) + 2 NH4Cl(aq) → ZnCl2(aq) + Mn2O3(s) + 2 NH3(aq) + H2O(l),

or if one also considers the hydration of the Mn2O3(s) sesquioxide into Mn(III) oxy-hydroxide:

Zn(s) + 2 MnO2(s) + 2 NH4Cl(aq) → ZnCl2(aq) + 2 MnO(OH)(s) + 2 NH3(aq)

Alternately, the reduction reaction of Mn(IV) can proceed further, forming Mn(II) hydroxide.

Zn(s) + 2MnO2(s) + 2 NH4Cl(aq) → ZnCl2(aq) + Mn(OH)2(s) + 2 NH3(aq)