A fuel cell converts the chemical energy of a fuel into electrical energy. In Chapter 7, you have learnt that hydrogen has a very high calorific value, but cannot be used the way we use other fuels because it forms an explosive mixture with air. A fuel cell is a safe way of utilising the chemical energy of hydrogen. What is great about this idea is that hydrogen can be produced by the electrolysis of water, and water is not in short supply the way fossil fuels are.
In a hydrogen fuel cell, hydrogen splits into ${\mathrm{H}}^{+}$ ions and electrons at the anode. The hydrogen ions pass through a selective membrane to the cathode. The electrons, on the other hand, travel along the external circuit (outside the cell) from the cathode to the anode, giving rise to a current that we can draw. At the anode, the hydrogen ions combine with electrons (that have travelled through the external circuit) and oxygen to form water. This is the other great thing about a hydrogen fuel cell—the only waste produced is water, which is not a pollutant. So, why have we not started using fuel cells on a large scale? That is because they are not yet efficient and inexpensive enough for common use.

What are the two advantages of a hydrogen fuel cell?

A fuel cell converts the chemical energy of a fuel into electrical energy. In Chapter 7, you have learnt that hydrogen has a very high calorific value, but cannot be used the way we use other fuels because it forms an explosive mixture with air. A fuel cell is a safe way of utilising the chemical energy of hydrogen. What is great about this idea is that hydrogen can be produced by the electrolysis of water, and water is not in short supply the way fossil fuels are.
In a hydrogen fuel cell, hydrogen splits into ${\mathrm{H}}^{+}$ ions and electrons at the anode. The hydrogen ions pass through a selective membrane to the cathode. The electrons, on the other hand, travel along the external circuit (outside the cell) from the cathode to the anode, giving rise to a current that we can draw. At the anode, the hydrogen ions combine with electrons (that have travelled through the external circuit) and oxygen to form water. This is the other great thing about a hydrogen fuel cell—the only waste produced is water, which is not a pollutant. So, why have we not started using fuel cells on a large scale? That is because they are not yet efficient and inexpensive enough for common use.

Explain briefly how a hydrogen fuel cell works.

A fuel cell converts the chemical energy of a fuel into electrical energy. In Chapter 7, you have learnt that hydrogen has a very high calorific value, but cannot be used the way we use other fuels because it forms an explosive mixture with air. A fuel cell is a safe way of utilising the chemical energy of hydrogen. What is great about this idea is that hydrogen can be produced by the electrolysis of water, and water is not in short supply the way fossil fuels are.
In a hydrogen fuel cell, hydrogen splits into ${\mathrm{H}}^{+}$ ions and electrons at the anode. The hydrogen ions pass through a selective membrane to the cathode. The electrons, on the other hand, travel along the external circuit (outside the cell) from the cathode to the anode, giving rise to a current that we can draw. At the anode, the hydrogen ions combine with electrons (that have travelled through the external circuit) and oxygen to form water. This is the other great thing about a hydrogen fuel cell—the only waste produced is water, which is not a pollutant. So, why have we not started using fuel cells on a large scale? That is because they are not yet efficient and inexpensive enough for common use.

Why are hydrogen fuel cells not used extensively?

“An image formed by a plane mirror is virtual, erect, laterally inverted and smaller than the object.” Is there anything wrong with this statement?

White light splits into its components on refraction because the components _____.

(Choose from the following: disperse/ refracts)

The spectrum of white light consists of _____ colours.

What is the sclera?

Cataract is caused by dietary deficiency.