Question

15. (a) What is rancidity? Mention any two ways by which
rancidity can be prevented.
[2]
(b) What is redox reaction? Identify the substance oxidised and
reduced in the following reaction :
[1]
MnO2 + 4HCI
MnCl2 + 2H2O + Cl2​

Answer 1

Answer :

a)${\purple{\boxed{\large{\bold{Rancidity}}}}}$

In our day - day to life , we aware that When the food materials prepared in fats and oils are kept for a long time, they start giving unpleasant smell and taste.

The oxidation of oils and fats in food resulting in a bad taste and smell is called rancidity.

➝Charactersitics of a rancid food

• It gives out unpleasant smell
• and also have a unpleasant taste .

➝Rancidity is called 'Vikritgandhita' in Hindi .

➝Rancidity of food can be prevented by following ways :

1. By adding anti - oxidants to food containing fats and oils . Example of anti - oxidants : BHA , BHT .
2. By storing foods away from light.
3. By packaging fat and oil containing foods in nitrogen gas.
4. By storing food in air - tight containers .
5. By keeping food in refrigerator.

b)${\purple{\boxed{\large{\bold{Redox\:Reaction}}}}}$

The reaction in which oxidation and reduction both occur simultaneously are called redox reactions.

➝Given Reaction :

$\sf\:MnO_{2}+4HCl\longrightarrow\:MnCl_{2}+2H_{2}O+Cl_{2}$

Here , HCl is oxidized to $\sf\:Cl_{2}$ and

$\sf\:MnO_{2}$ is reduced $\sf\:MnCl_{2}$.

$\rule{200}2$

More About the topic :

➝Oxidation

1. Addition of oxygen
2. Removal of hydrogen

➝Reduction

1. Removal of oxygen
2. Addition of hydrogen.

Answer 2

Answer :-

15 (a) What is Rancidity? Mention any two ways by the which rancidity can be prevented.

☛ The oxidation of oils or fats in a food resulting into a bad as bad smell and a bad test is called rancidity.

we have often noticed that of food containing oil or fat ,if left for a long time i. e., stale food, develops a bad taste and bad smell .This is because the oil and fats present in soft foods gets oxidized with the passage of time the product formed as a result of this oxidation are violets and have a bad smell for this reason the test of the food also change.

▪ Methods to rancidity ▪

☛ By adding anti -oxidants.

• In the food industry , a number of a special type of substance are added before packing which slow down the process of oxidation substance are called antioxidants.

☛ Vacuum Packing.

• In a number of cases after packing the food, the container is evacuated before sealing so that no air/oxygen is available to bring about the oxidation of the food.

☛ Replacing air by Nitrogen.

• In some food stuffs the air present around them is replaced by nitrogen in the packet containing the food stuff. Thus the oxidation of the food stuff is prevented.
• For example bags of chips are flushed with nitrogen to prevent them from oxidation.

☛ Refrigeration of the food-stuff.

• This method is very common at home .We keep the food stuff in the refrigerator due to lower temperature ,oxidation is slowed down.

(b) What is Redox reaction? Identify the substance oxidised and reduced in following reaction.

(i) MnO2+4HCL ➝ MnCl2 + 2H2O +Cl2

☛ Reduction and Oxidation always occur together.Hence, these reactions are called Redox reaction.

(i) MnO2+4HCL ➝ MnCl2 + 2H2O +Cl2

Here, HCL is oxidised to Cl2 and Mno2 is reduced to MnCl2.

_______________________________

More information!!!!!!

☛ Oxidation is a process which involves gain of oxygen or lose of hydrogen.

☛ Reduction is a process which involves gain of hydrogen or loss of oxygen.

☛ Reducing agent is a substance which gives hydrogen organs oxygen.

☛ Oxidizing agent is a substance which gives oxygen or gain hydrogen.