Electrolysis Class-10 Goyal Brothers ICSE Chemistry Solutions Ch-6

Electrolysis Class-10 Goyal Brothers ICSE Chemistry Solutions Ch-6. Step by Step Goyal Brother Prakashan Chemistry Solutions of Exercise and Objective Type Questions Chapter-6 Electrolysis for ICSE Class 10 . Visit official Website CISCE  for detail information about ICSE Board Class-10 Chemistry .

Electrolysis Class-10 Goyal Brothers ICSE Chemistry Solutions Ch-6


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Exercise   Page-118 to 119

Electrolysis Class-10 Goyal Brothers ICSE Chemistry Solutions Ch-6

Question 1.

(a) What do you understand by the following terms

(i) electrolyte,

(ii) non-electrolyte?
(b) Pick out electrolytes and non-electrolytes from the following :

(i) sugar solution

(ii) dilute sulphuric acid

(iii) fused lead bromide

(iv) solution of sulphur in carbon disulphide
(v) aqueous sodium chloride solution,

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(vi) solid potassium chloride

(vii) ethyl alcohol

(viii) acidulated water

(ix) caustic soda solution   (x) petrol.

Answer :

(a)

(i) electrolyte-An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water. The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent

(ii) non-electrolyte- a substance that does not readily ionize when dissolved or melted and is a poor conductor of electricity.

(b) electrolytes and non-electrolytes :

(i) sugar solution– non-electrolyte

(ii) dilute sulphuric acid–electrolytes
(iii) fused lead bromide–electrolytes

(iv) solution of sulphur in carbon disulphide–Non electrolytes
(v) aqueous sodium chloride solution, –electrolytes

(vi) solid potassium chloride- — non-electrolyte

(vii) ethyl alcohol— non-electrolyte

(viii) acidulated water–electrolytes

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(ix) caustic soda solution–electrolytes

(x) petrol.– non-electrolyte

Question 2. What do you understand by the following terms :
(a) electrolysis, (b) electrode, (c) cathode, (d) anode, (e) cation, (f) anion, (g) voltameter ?

Answer :

(a) electrolysis– ,A process in which a chemical change, especially decomposition, is brought about by passing an electric current through a solution of electrolytes so that the electrolyte’s ions move toward the negative and positive electrodes and react with them.

 (b) electrode,-An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air)

 (c) cathode-A cathode is the electrode from which a conventional current leaves a polarized electrical device.

(d) anode- An anode is an electrode through which the conventional current enters into a polarized electrical device. This contrasts with a cathode, an electrode through which conventional current leaves an electrical device. A common mnemonic is ACID, for “anode current into device

 (e) cation-a positively charged ion that is attracted to the cathode in electrolysis. any positively charged atom or group of atoms (opposed to anion)

 (f) anion- a negatively charged ion, as one attracted to the anode in electrolysis. any negatively charged atom or group of atoms (opposed to cation)

 (g) voltammeter – A method of determining the chemical makeup of a sample substance by measuring electrical activity, or the accumulation of chemicals, on electrodes placed in the substance.

Question 3. Pick out the cations and anions from the following:
(i) SO42-   (ii) Pb+2    (iii) NH+4   (iv) OH-  (v) NO3-  (vi) H+   (vii) Ag+   (vii) Cu2+  (ix) CN –    (x) Cl-

Answer :

(i) SO42-  — anions

 (ii) Pb+2   — cations

 (iii) NH+4  — cations

(iv) OH-   — anions

(v) NO3-  — anions

 (vi) H+  — cations

(vii) Ag+  — cations

 (vii) Cu2+ — cations

 (ix) CN –   — anions

 (x) Cl- — anions

Question 4. Fill in the blanks.

(i) The metal plate through which current enters into an electrolyte is called _________. It has _______ of electrons.

(ii) The metal plate through which ________ leaves an electrolyte is called . It has __________ of electrons.

(iii) The ions which discharge on the negative electrode during electrolysis are________ electrons. Thus the ions are said to be __________.
(iv) The ions which discharge on the positive electrode during electrolysis are ___________  electrons. Thus the ions are said to be ___________ .

(v) Hydrogen and metallic ions are _________ , because they are __________ electrons.

(vi) Non-metallic ions are __________ because they are __________ electrons.

Answer :

(i) The metal plate through which current enters into an electrolyte is called _____Anode____. It has __Lack_____ of electrons.

(ii) The metal plate through which ____Current____ leaves an electrolyte is called . It has ____excess______ of electrons.

(iii) The ions which discharge on the negative electrode during electrolysis are____gain____ electrons. Thus the ions are said to be __cation________.
(iv) The ions which discharge on the positive electrode during electrolysis are _____loose______  electrons. Thus the ions are said to be ____anion_______ .

(v) Hydrogen and metallic ions are ___cation______ , because they are ______lack____ electrons.

(vi) Non-metallic ions are _____electronegative_____ because they are _______gain___ electrons.

Question 5.

(a) What do you understand by the term “electrolytic dissociation'”?

(b) The dissociation of sodium chloride solution in water is 99%. What do you mean by the statement?

Answer

(a)  electrolytic dissociation-In electrolytic, or ionic, dissociation, the addition of a solvent or of energy in the form of heat causes molecules or crystals of the substance to break up into ions (electrically charged particles). Most dissociating substances produce ions by chemical combination with the solvent

(b)  It means that NACL when dissolved in water gets dissociated and can be used as an electrolyte and it allows 99% of current through it

Question 6. Solid sodium chloride is a bad conductor of electricity. However, fused sodium chloride conducts electric current. Explain on the basis of the theory of ionisation.

Answer :

1. In solid sodium chloride there is the force of attraction between the two atoms as they form the ionic bond by sharing of electrons .Therefore as a result there is no flow of electricity.
2.In case of molten sodium chloride the atoms dissociate and form ions .As a result there are free electrons which are required to the flow of electricity . Therefore molten sodium chloride conduct electricity

Question 7. How does lead bromide ionise in water when water is a polar covalent compound?

Answer :

Rather, compounds with covalent bonds dissolve in water. The water surrounds the polar sites of the molecules at the interface with the solute (whether it is a solid, a liquid, or a gas) and strips the molecules away. … The solvent particles must move apart to make room for solute particles

Question 8. By giving at least four examples, define or explain the meaning of (a) strong electrolyte (b) weak electrolyte, (c) non-electrolyte.

Answer :

(a) strong electrolyte —

HCl, HBr, , HNO3, HClO3, HClO4, and H2SO4 NaOH, KOH, LiOH, Ba(OH)2, and Ca(OH)2 NaCl, KBr, MgCl

(b) weak electrolyte-HF, HC2H3O NH3 (ammonia),

(c) non-electrolyte.- A common example of a nonelectrolyte is glucose, or C6H12O6. Glucose (sugar) readily dissolves in water, but because it does not dissociate into ions in solution, it is considered a nonelectrolyte; solutions containing glucose do not, therefore, conduct electricity. “nonelectrolyte.” “solute

Question 9. Pick out strong electrolytes and weak electrolytes from the following aqueous solutions :

(i) copper sulphate,

(ii) carbonic acid,

(iii) limewater,

(iv) sodium hydroxide,
(v) sodium carbonate,

(vi) nitric acid,

(vii) lead nitrate

Answer :
(i) copper sulphate,–strong electrolytes

(ii) carbonic acid,–weak electrolytes

(iii) limewater,—strong electrolytes

(iv) sodium hydroxide,–strong electrolytes
(v) sodium carbonate,–strong electrolytes

(vi) nitric acid,–strong electrolytes

(vii) lead nitrate.–strong electrolytes

Question 10. Write all the ions present in aqueous solutions of the following :
(i) caustic potash,

(ii) acetic acid,

(iii) magnesium sulphate,
(iv) acetic acid,

(v) phosphoric acid,

(vi) NH4Cl solution.

Answer :

(i) caustic potash, K+ ion OH-  ion

(ii) acetic acid, CH3COO-    and H+ ion

(iii) magnesium sulphate, SO4-    and Na+ ion
(iv) acetic acid,

(v) phosphoric acid, PO4-    and H+ ion

(vi) NH4Cl solution. Cl-    and NH4+ ion

Question 11.

(a) Al3+ : Cu2+ ; Na+ ; Zn2+  ions are present in an aqueous solution, such that the concentration of ions is the same. Write the order of discharge of ions.

(b) Amongst the OH ions and Br ions which are likely to discharge first?

Answer :

(a )The order of discharge of ions is Al+3 ,Cu+2 ,Na+ ,Zn+2 because as the concentration is same, an ion placed lower in electrochemical series get preferentially discharged.

(b )OH is likely to discharge first in comparison to Br ions

Question 12.  By giving an example, explain how nature of the anode changes the preference of discharge of anions.

Answer :

Nature of the Electrode: This is not as important as either of the other two factors, except in certain cases. For example in the electrolysis of molten sodium chloride using a mercury cathode, sodium ions are discharged in preference to hydrogen ions which are lower in the series.

Question 13.  By writing ionic reactions at the cathode and anode, describe electrolysis of water using platinum electrodes

Answer :

Electrolysis of water is the process of using electricity to decompose  water into oxygen and hydrogen gas. Hydrogen gas released in this way can be used as hydrogen fuel, or remixed with the oxygen to create oxyhydrogen gas, which is used in welding and other applications

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