Question

What would be the reason for the following?
a) Aluminium foils are used to wrap food items.
b) Immersion rods for heating liquids are made up of metallic substances.
c) Copper cannot displace zinc from its salt solution.
d) Sodium and potassium are stored in kerosene.

Answer 1

We know very well that according to electrochemical series a more reactive element placed at the top can easily displace a less reactive element placed at bottom from their salt solution and the reactivity of the element is directly related to its oxidation and reduction potentials.

Complete answer:
As we know that according to electrochemical series a more reactive element placed at the top can easily displace a less reactive element placed at bottom from their salt solution and the reactivity of the element is directly related to its oxidation and reduction potentials. Also we know that metals have a property of conducting electricity and heat.

a) Keeping these properties in mind, let us discuss the given option one by one. So, the first one is Aluminium foils which are used to wrap food items, we know very well that Aluminium is the less reactive metal so when we wrap food into aluminium foils, it does not react with the substances present in the food material and thus do no change the taste of food and keep the food warm.

b) Next we have immersion rods which are used to heat liquids are made up of metallic substances, so we know that metals have a very good property of conducting heat and electricity. That is why immersion rods requiring electricity supply to get heated are composed of metallic substances.

c) Now we know that according to the electrochemical series, copper is less reactive than zinc metal and a more reactive element can displace a less reactive element so following the same reason we can say that zinc being more reactive can displace the less reactive copper from its salt solution but copper cannot displace zinc from its salt solution.

d) Lastly we have sodium and potassium which we already know are highly reactive metals and they can easily react with the oxygen present in the air and result in fire hazards, that is why they are stored in kerosene.

Note: Reactivity of metals decreases down the electrochemical series as the oxidation potential decreases and the reactivity increases when the reduction increases. Thus, zinc sulphate is stored in copper containers but copper sulphate is not stored in zinc containers.