FBISE 9th Class Chemistry Chapter 7 Electrochemistry Short Questions Answers
FBISE 9th class Chemistry Chapter 7 Electrochemistry Short Questions with answers are combined for all 9th class(Matric/ssc) Level students. Here You can prepare all Chemistry Chapter 7 Electrochemistry short question in unique way and also attempt quiz related to this chapter. Just Click on Short Question and below Answer automatically shown. After each question you can give like/dislike to tell other students how its useful for each.
Class/Subject: 9th Class Chemistry
Chapter Name: Electrochemistry
Board: Federal Board
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FBISE 9th Class Chemistry Chapter 7 Electrochemistry Short Questions Answers
What is meant by electrochemistry?
The branch of chemistry that deals with the relationship between electricity and chemical reactions are called electrochemistry.
Oxidation is defined as the gain of oxygen atoms or loss of hydrogen atoms by an element.
What is an oxy-acetylene flame?
Acetylene (C2H2) is commercially used for cutting and welding metals. When acetylene burns, it produces a very hot flame known as oxy-acetylene flame.
Reduction is defined as the removal of oxygen or addition of hydrogen or gain of electron or decrease in oxidation number during a chemical reaction.
Define oxidation states or oxidation numbers?
Oxidation state or oxidation number is defined as the number of charges an atom will have in a molecule of a compound.
Define oxidizing agent?
An oxidizing agent is a reactant containing the element that is reduced (gains electrons) in a chemical reaction.
Define Reducing agent?
A reducing agent is a reactant containing the element that is oxidized (loses electrons) in the chemical reaction.
Define Oxidation-reduction reaction or redox reactions?
Such a reaction that involved the transfer of electrons is known as an oxidation-reduction reaction. These reactions are also called redox reactions.
Define Electrochemical cell?
Devices that convert chemical energy into electrical energy or vice versa are called electrochemical cells.
Define Electrolytic cell?
An electrochemical cell that uses electrical energy to drive a chemical reaction is called an electrolytic cell.
Define Galvanic cell?
An electrochemical cell that converts chemical energy into electrical energy is called a galvanic cell.
Define spontaneous reaction?
The reaction that takes place of its own, without any external assistance is called spontaneous reaction.
Define non-spontaneous reaction?
The reaction which is the reverse of a spontaneous reaction and takes place by supplying energy to the system from an external source is called a non-spontaneous reaction.
The apparent charge on an atom, ion, or molecule is called valency, is written as the sign followed by the number i.e. 2+.
What are electrolytes?
The substances, which can conduct electricity in their solutions or molten states, are called electrolytes. For example, solutions of salts, acids, or bases are good electrolytes.
What are strong electrolytes?
The electrolytes which ionize completely in an aqueous solution and produce more ions are called strong electrolytes. For example, NaCl, NaOH, H2SO4, are strong electrolytes.
Chemical species which carry a positive charge. E.g. Na+, K+, etc.
Chemical species carry a negative charge. E.g. O2-, Cl-, etc.
What is a half cell?
A galvanic cell consists of two cells one having a cathode while the other having anode end which is connected with a salt bridge. Each of these is known as a half cell.
What is meant by the salt bridge?
Salt-bridge is a U-shaped glass tube that consists of a saturated solution of strong electrolyte supported in a jelly-type material. The ends of the U-shaped glass tube are sealed with a porous material like glass wool. The function of the salt bridge is to keep the solutions of two half cells neutral by providing a pathway for the migration of ions.
It is a redox reaction that takes place by the action of air and moisture with metals. For example, rusting of iron.
What is meant by rust?
It is a redox reaction that takes place when the iron is exposed to air and moisture. The chemical formula of rust is Fe2O3 H2O.
Alloy is a homogeneous mixture of one metal with one or more metals or nonmetals. For example, stainless steel is an alloy of iron, chromium, and nickel.
Write oxidation numbers of oxygen in its binary compounds?
i. Normal oxides -2
ii. Peroxides -1
iii. OF2 +2
Write construction of Down’s cell?
This electrolytic cell is a circular furnace. In the center, three is a large block of graphite, which acts as an anode while the cathode around it is made of iron.
What is meant by galvanizing?
The process of coating a thin layer of zinc on iron is called galvanizing.
What is the principle of electroplating?
The principle of electroplating is to establish an electrolytic cell in which anode is made of the metal to be deposited and cathode of the object on which metal is to deposit. The electrolyte is an aqueous solution of a salt of the respective metals.
Why tin-plated steel is used to make food cans?
They are made from steel with a thin coating of tin to prevent corrosion. Tin plated steel I used to make cans. The food and beverage industries use tin-plated steel cans. This is because the components of food beverages and preservatives contain organic acids or salts. They may from toxic substances by reacting with iron. Tin plating is non-poisonous and prevents corrosions.
Write three uses of the electrolytic cell?
i. Down’s cell is used for the commercial preparation of sodium metal. It produces chlorine gas as a by-product.
ii. Nelson’s cell is used for the commercial preparation of sodium hydroxide.
iii. It is used for the purification of copper.
In which direction do electrons flow when the key is pressed?
Electrons leave the Zn-electrode and then move towards Cu-electrodes.
Describe how a battery produces electrical energy?
A battery is a galvanic cell or a group of galvanic cells joined in series. It generates an electric current by a redox reaction. When connected in a circuit its anode oxidizes by releasing electrons. These electrons through the external circuit are to flow towards the cathode. At the cathode, these electrons reduce oxidizing agent present in the electrolyte.
Why the process of rusting does only occur on iron and not on the surface of aluminum?
Aluminum corrodes but it does not rust. Rust refers only to iron and steel corrosion. A very hard material aluminum oxide protects the aluminum from further corrosion. In comparison to that when iron corrodes. Its color changes and produces large red flakes known as rust. Unlike aluminum oxide, the expanding and flaking of rust exposes the new metal to further rusting.
Explain the role of O2 in rusting?
The free electrons move through iron sheets; until they reach a region of relatively high oxygen concentration, near the surface surrounded by a water layer. This region acts as a cathode and electrons reduce the oxygen molecule in the presence of H+ ions.
O2 + 4H+ → 2H2O
What is the shape of the cathode Nelson’s cell? Why it is perforated?
In Nelson’s cell, the cathode is internally lined with the asbestos diaphragm. The cathode is a U-shaped perforated iron from where sodium hydroxide solution slowly percolates in a catch basin.
In the following reaction, how can you justify that H2S is oxidized and SO2 is reduced?
SO2 + 2H2S → 2H2O + 3S
As hydrogen is removal from H2S, therefore H2S is oxidized, while removal of oxygen takes place in SO2, therefore SO2 is reduced.
How can you justify that the following reactions are not only an oxidation reaction but also a complete redox reaction?
FeO Co → Fe + CO2
When FeO reacts with CO, oxygen is removed from FeO which shows a reduction process. On the other hand, when oxygen is added to CO it shows an oxidation process. Therefore, it is a complete redox reaction.
Write application of galvanic cell?
As a result of the redox reaction, an electric current is produced. The batteries which are used for starting automobiles, running calculators and toys, and to lit the bulbs work on the same principle.
What do you know about anodizing aluminum?
Anodized aluminum sheets are widely used in buildings nowadays. Anodized aluminum can absorb dyes. The dying of aluminum can produce metallic red, metallic blue, or other metallic colors on the metal surface.
What is electroplating?
The electrolytic process used to deposit one metal on another metal is called electroplating.
Where do the electrons flow from the Zn electrode in Daniel’s cell?
In Daniel’s cell, the electron takes to flow from the Zn electrode (anode) towards the cathode made up of copper through the external circuit.
Why an iron grill is painted frequently?
The iron grill is painted frequently to protect it from rusting. The paint layer protects iron from the attack of moisture and oxygen.
In electroplating silver, from where Ag+ come and where they deposit?
In the electroplating of silver, Ag+ ions come from an anode while they deposit at the cathode.
What is the nature of the electrode used in the electroplating of chromium?
In the electroplating of chromium, the anode is made of antimonial lead while the object to be electroplated acts as a cathode.
Who was A. Volta?
Volta (1745 – 1827) was an Italian physicist known especially for the development of the first electric cell in 1800.
What is meant by stainless steel?
It is an alloy that is made up of iron, chromium, and nickel. This does not corrode.