Explain the ''Corrosion'' terms with one example.
Corrosion:
Corrosion is defined as a process where materials, usually metals, deteriorate as a result of a chemical reaction with air, moisture, chemicals, etc.
For example, iron, in the presence of moisture, reacts with oxygen to form hydrated iron oxide.
$4Fe + 3{O_2} + n{H_2}O \to \mathop {2F{e_2}{O_3}.n{H_2}O}\limits_{Hydrated\,\,iron\,\,oxide} $
This hydrated iron oxide is rust.
Why should a magnesium ribbon be cleaned before burning in air ?
A solution of a substance $‘X’$ is used for whitewashing.
$(i)$ Name the substance $‘X’$ and write its formula.
$(ii)$ Write the reaction of the substance $‘X’$ named in $(i)$ above with water.
What is a balanced chemical equation ? Why should chemical equations be balanced ?
Balance the following chemical equations.
$(a)$ $HNO _{3}+ Ca ( OH )_{2} \longrightarrow Ca \left( NO _{3}\right)_{2}+ H _{2} O$
$(b)$ $NaOH + H _{2} SO _{4} \longrightarrow Na _{2} SO _{4}+ H _{2} O$
$(c)$ $NaCl + AgNO _{3} \longrightarrow AgCl + NaNO _{3}$
$(d)$ $BaCl _{2}+ H _{2} SO _{4} \longrightarrow BaSO _{4}+ HCl$
What does one mean by exothermic and endothermic reactions ? Give examples.