What is a primary battery? Provide a note on primary batteries and a note on dry cells.

(N/A) primary battery is a type of electrochemical cell in which the chemical reaction occurs only once. After use over a period of time,the reactants are consumed,the battery becomes dead,and it cannot be recharged or reused.
Dry Cell (Leclanché Cell):
It is the most common example of a primary battery.
Uses: It is commonly used in transistors,toys,and clocks.
Construction:
Anode: The cell consists of a zinc container that acts as the anode.
Cathode: The cathode is a carbon (graphite) rod,which is placed vertically in the center of the zinc cylinder.
Electrolyte: The space between the electrodes is filled with a moist paste of ammonium chloride $(NH_{4}Cl)$ and zinc chloride $(ZnCl_{2})$. The carbon rod is surrounded by a mixture of powdered manganese dioxide $(MnO_{2})$ and carbon.
Reactions:
Oxidation at the anode:
$Zn_{(s)} \rightarrow Zn^{2+} + 2e^{-}$
Reduction at the cathode:
$MnO_{2} + NH_{4}^{+} + e^{-} \rightarrow MnO(OH) + NH_{3}$
The $Zn^{2+}$ ions produced react with $NH_{3}$ to form a complex,$[Zn(NH_{3})_{4}]^{2+}$.
Overall cell reaction:
$Zn_{(s)} + 2MnO_{2} + 2NH_{4}^{+} \rightarrow Zn^{2+} + 2MnO(OH) + 2NH_{3}$
Cell potential: The potential of this cell is approximately $1.5 \ V$.