Name: Numerical Form of Nernst's Equation
Uploaded: 2019-07-19
Duration: 2 min 49 s
Description: Nernst equation provides the concentration dependence of the potentials of the electrodes and the cells. Let’s analyse the importance of this equation!

Question

Complete the table below to estimate the boiling point and atomic radius of caesium. Comment also on the reactivity of potassium and caesium with water.

Group I metal	Density $/ g / {Cm}^{3}$	Radius of metal atom $(nm)$	Boiling point $(° C)$	Reactivity with water
Sodium	$0.97$	$0.191$	$883$	Floats and fizzes quickly on the surface, disappears gradually and does not burst into flame.
Potassium	$0.86$	$0.235$	$760$	_____
Rubidium	$1.53$	$0.250$	$686$	Reacts instantaneously, fizzes and burst into flame then spits violently and may explode.
Caesium	$1.88$	_____	_____	_____

Accepted Answer

Reactivity of potassium with water: Potassium is the third alkali metal and its reaction with water is more vigorous than sodium. It floats on the surface of the water and fizzes vigorously. It disappears and catches fire with a lilac flame.

Reactivity of caesium with water: Caesium is the fourth alkali metal which is more reactive than the metals above it in the periodic table. It reacts vigorously with water and explodes. It can also shatter the container.

The radius of the atom is the distance between the outermost shell and the centre of the nucleus. As moving down the group we can see that the atomic radius is increasing and the boiling point is decreasing. Thus, the atomic radium of caesium atom is $0.265 nm$ , and its boiling point is $671 ° C$ .

The complete table is as follows:

Group I metal Density $/ g / {Cm}^{3}$ Radius of metal atom $0.191$ Boiling point $(° C)$ Reactivity with water

Sodium $0.97$ $0.191$ $883$ Floats and fizzes quickly on the surface, disappears gradually and does not burst into flame.

Potassium $0.86$ $0.235$ $760$ It floats on the surface of the water and fizzes vigorously. It disappears and catches fire with a lilac flame.

Rubidium $1.53$ $0.250$ $686$ Reacts instantaneously, fizzes and burst into flame then spits violently and may explode.

Caesium $1.88$ $0.265$ $671$ It reacts vigorously with water and explodes. It can also shatter the container.


At start	Colour of metal	grey	_____	silver-coloured	silver-coloured	_____
At start	Colour of solution	colourless	_____	blue	blue	colourless
At finish	Colour of metal	coated with silver coloured crystals	_____	coated with brown solid	silver-coloured	coated with silver-coloured crystals
At finish	Colour of solution	colourless	_____	colourless	blue	_____


At start	Colour of metal	grey	grey	silver-coloured	silver-coloured	brown
At start	Colour of solution	colourless	blue	blue	blue	colourless
At finish	Colour of metal	Coated with silver coloured crystals	Coated with brown solid	Coated with brown solid	silver-coloured	Coated with silver-coloured crystals
At finish	Colour of solution	colourless	colourless	colourless	blue	blue

Metal	Relative abundance in Earth's crust	Cost of extraction	Density	Strength	Melting Point $(° C)$	Electrical conductivity relative to iron
Iron	$2^{nd}$	low	high	high	$1535$	$1.0$
Titanium	$7^{th}$	very high	low	high	$1660$	$0.2$
Aluminum	$1^{st}$	high	low	medium	$660$	$3.5$
Zinc	$19^{th}$	low	high	low	$419$	$1.7$
Copper	$20^{th}$	low	high	medium	$1083$	$6.0$
Tin	$40^{th}$	low	high	low	$231$	$0.9$
Lead	$30^{th}$	low	very high	low	$327$	$0.5$

Important Questions on Patterns and Properties of Metals

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