Redox reactions 2

Question 1

HNO 3 acts only as an oxidizing agent while nitrous acid acts as both oxidizing and reducing agent. Justify

Answer 1

In HNO3, N is in its max. oxidation state. It can only gain electrons and cannot lose. Whereas HNO2, N has Oxidation state +3, it can give or lose electrons, hence it is an oxidizing and reducing agent.

Question 2

Define direct redox reactions

Answer 2

Redox reactions in which oxidation and reduction occurs in the same vessel are known as direct redox reactions.

Question 3

Define indirect redox reaction.

Answer 3

Redox reactions in which oxidation and reduction takes place in different vessels are called indirect redox reactions.
(Medium used -> Electrochemical cell)

Question 4

Define an electrochemical cell

Answer 4

Device used to convert chemical energy produced in an indirect redox reaction into electrical energy.
also called Galvanic cell/ Voltaic cell/ Daniel cell.

Question 5

what is a salt bridge and write its function.

Answer 5

The salt fridge is a U tube containing potassium chloride or ammonium nitrate solution usually solidified by boiling with agar agar gel and later cooling with a jelly like substance.
FUNCTION: -
1. It allows the moment of ions without mixing the two solutions.
2. Helps maintain electrical neutrality of the solutions in the two half cells due to flow of Electrons.

Question 6

/

Answer 6

Interphase between solid and aqueous solutions

Question 7

//

Answer 7

Salt bridge

Question 8

Electron potential

Answer 8

Tendency of an electrode to lose or gain electrons it is the potential associated with each electrode.

Question 9

Standard electrode potential.

Answer 9

If the concentration of each solution taking part in the electrode reaction is unity. ( If any gas appears in electrode reaction, it is taken as one atmosphere).

Question 10

EMF

Answer 10

Electromotive cell

Question 11

The Standard Electrode potential of Hydrogen is ___

Answer 11

0

Question 12

-ve and +ve EMF

Answer 12

• Negative E o Means that the Redox couple is a stronger reducing agent than H+/H2 couple.
• Positive E o means that the redox couple is a weaker reducing agent than H+/ H2 couple.

Question 13

Redox couple

Answer 13

• It is defined as having together the oxidized and reduced form of a substance taking part in an oxidation or reduction.
• Represented by separating the oxidized form from the reduced form by a vertical line or slash.

Question 14

Describe an Electrochemical cell.

Answer 14

• Left beaker contains zinc road dipped in zinc sulfate solution and the right speaker contains copper road dipped in copper sulfate solution
• They are connected by a thin wire and zinc sulfate and copper sulfate solutions they are connected by salt bridge.
• The electrons move from zinc road to copper road while the current flows from cathode to anode.
• The Baker in which oxidation and reduction takes place oxidation half cell and reduction half cell respectively.