Basic principle of hydrogen economy is transportation and storage of energy in the form of liquid or gaseous hydrogen. Which property of hydrogen may be useful for this purpose? Support your answer with the chemical equation if required.
Basic principle of hydrogen economy is transportation and storage of energy in the form of liquid or gaseous hydrogen. Hydrogen is a gas at room temperature.
However, by cooling and applying high pressure, gaseous $\mathrm{H}_2$ can be converted into liquid $\mathrm{H}_2$ which has much smaller volume and hence can be transported easily. Thus, the basic property of hydrogen which is useful for hydrogen economy is that it can be converted into a liquid by cooling under high pressure.
50 What is the importance of heavy water?
Following are the importance of heavy water
(i) It is extensively used as a moderator in nuclear reactors.
(ii) It is used as a tracer compound in the study of reaction mechanism.
(iii) It is used for the preparation of other deuterium compounds such as $\mathrm{CD}_4, \mathrm{D}_2 \mathrm{SO}_4$, etc.
Write the Lewis structure of hydrogen peroxide.
The Lewis structure of hydrogen peroxide is
An acidic solution of hydrogen peroxide behaves as an oxidising as well as reducing agent. Illustrate it with the help of a chemical equation.
Following are the chemical equation of $\mathrm{H}_2 \mathrm{O}_2$ in which it behaves as an oxidising as well as reducing agent
(i) $\mathrm{H}_2 \mathrm{O}_2$ oxidises acidified KI to iodine.
$$2 \mathrm{KI}+\mathrm{H}_2 \mathrm{O}_2+\mathrm{H}_2 \mathrm{SO}_4 \longrightarrow \mathrm{I}_2+\mathrm{K}_2 \mathrm{SO}_4+2 \mathrm{H}_2 \mathrm{O}$$
(ii) $\mathrm{H}_2 \mathrm{O}_2$ reduces $\mathrm{KMnO}_4$ to $\mathrm{MnO}_2$ in alkaline medium.
$$2 \mathrm{KMnO}_4+3 \mathrm{H}_2 \mathrm{O}_2 \longrightarrow 2 \mathrm{MnO}_2+2 \mathrm{KOH}+3 \mathrm{O}_2+2 \mathrm{H}_2 \mathrm{O}$$
With the help of suitable examples, explain the property of $\mathrm{H}_2 \mathrm{O}_2$ that is responsible for its bleaching action?
The bleaching action of hydrogen peroxide is due to the nascent oxygen which it liberates on decomposition.
$$\mathrm{H}_2 \mathrm{O}_2 \longrightarrow \mathrm{H}_2 \mathrm{O}+[\mathrm{O}]$$
The nascent oxygen combines with colouring matter, in turn, gets oxidised. Thus, the bleaching action of $\mathrm{H}_2 \mathrm{O}_2$ is due to the oxidation of colouring matter by nascent oxygen. It is used for the bleaching of delicate materials like ivory, feathers, silk, wool etc.
Colouring matter $+[\mathrm{O}] \longrightarrow$ Colourless matter