Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
Decomposition reactions are those in which a compound breaks down to form two or more substances. These reactions require a source of energy to proceed. Thus, they are the exact opposite of combination reactions in which two or more substances combine to give a new substance with the release of energy.
Decomposition reaction : $AB +$ Energy $\longrightarrow A + B$
$2{{H}_{2}}{{O}_{(l)}}\xrightarrow{\text{ Electroly}sis}2{{H}_{2(g)}}+{{O}_{2(g)}}$
Combination reaction : $A+B \longrightarrow A B+$ Energy
$2{{H}_{2(g)}}+{{O}_{2(g)}}\to 2{{H}_{2}}{{O}_{(l)}}\,+$ Energy
Explain the ''Rancidity'' terms with one example.
What do you mean by a precipitation reaction? Explain by giving examples.
Write the balanced chemical equation for the following and identify the type of reaction in each case.
$(a)$ Potassium bromide $(aq)$ $+$ Barium iodide$(aq)$ $\rightarrow$ Potassium iodide$(aq)$ $+$ Barium bromide$(s)$
$(b)$ Zinc carbonate$(s)$ $\rightarrow$ Zinc oxide$(s)$ $+$ Carbon dioxide$(g)$
$(c)$ Hydrogen$(g)$ $+$ Chlorine$(g)$ $\rightarrow$ Hydrogen chloride$(g)$
$(d)$ Magnestum $(s)$ $+$ Hydrochloric acid$(aq)$ $\rightarrow$ Magnesium chloride$(aq)$ $+$ Hydrogen $(g)$
Identify the substances that are oxidised and the substances that are reduced in the following reactions.
$(i)$ $4 Na ( s )+ O _{2}( g ) \rightarrow 2 Na _{2} O ( s )$
$(ii)$ $CuO ( s )+ H _{2}( g ) \rightarrow Cu ( s )+ H _{2} O ( l )$
Oil and fat containing food items are flushed with nitrogen. Why ?