P-1 Chemical reactions and equations — Science STD 10 — Question

1. Oxidation reaction
2. Reduction reaction.

1. Oxidation reaction:
Examples:
(1) When carbon burns in air, it forms carbon dioxide. In this reaction carbon accepts oxygen, therefore, this is an oxidation reaction.
$C _{( s )}+ O _{2( g )} \rightarrow CO _{2( g )}$
(2) When sodium reacts with ethyl alcohol, sodium ethoxide and hydrogen gas is formed. In this reaction, hydrogen is removed from ethyl alcohol, therefore this is an oxidation reaction.
$2 C _2 H _5 OH _{( i )}+2 Na \longrightarrow 2 C _2 H _5 ONa + H _2 \uparrow$
(3) Acidified potassium dichromate $\left( K _2 Cr _2 O _7 / H _2 SO _4\right)$ oxidises ethly alcohol to acetic acid.
$CH _3- CH _2- OH \frac{2( O )}{ K _2 Cr _2 O _7 / H _2 SO _4} CH _3- COOH + H _2 O$
2. Reduction reaction:
Examples:
(1) When hydrogen gas is passed over black copper oxide a reddish coloured layer of copper is
formed.
In this reaction an oxygen atom removed from $CuO$ to form copper, hence, this is reduction.
$
CuO _{(8)}+ H _{2( g )} \rightarrow Cu _{( s )}+ H _2 O _{( l )}
$
(2) when hydrogen gas is passed over red hot coke, methane is obtained.
Here, hydrogen is added to coke (carbon). Hence, this is reduction.
$C _{( s )}+2 H _{2( g )} \rightarrow CH _{4( g )}$