የምዕራፍ ማስታወሻዎችና የመልመጃ ጥያቄዎች

የ12ኛ ክፍል ኬሚስትሪ ምዕራፍ 2፦ ኤሌክትሮኬሚስትሪ

በዚህ ገጽ ያለው ሁሉ ለ12ኛ ክፍል የኬሚስትሪ መፅሐፍ ምዕራፍ 2 ነው፦ ምዕራፉ የሚሸፍነው፣ አጭር ማስታወሻዎቹ፣ የመልመጃ ጥያቄዎች ከመልሶቻቸው ጋር፣ እና ቪዲዮ ባለበት የትምህርቱ ቪዲዮ።

5
ካርዶች: 10
የምዕራፍ 2 የመልመጃ ጥያቄዎች: 57–135
የምዕራፍ 2 የመፅሐፍ ገጾች

ምዕራፍ 2 የሚሸፍነው

1.Oxidation-Reduction Reactions
2.Oxidation
3.Reduction
4.Balancing Oxidation-Reduction (Redox) Reactions
5.Electrolysis of Aqueous Solutions
6.Electrolytic Cells
7.Preferential Discharge
8.Electrolysis of Some Selected Aqueous Solutions
9.Quantitative Aspects of Electrolysis
10.Faraday's First Law of Electrolysis
11.Faraday's Second Law of Electrolysis
12.Industrial Application of Electrolysis
13.Volatic Cells

የምዕራፍ 2 አጭር ማስታወሻዎች

በ12ኛ ክፍል የኬሚስትሪ ገጽ ላይ በዚህ ምዕራፍ ሥር የተመዘገቡት ካርዶች። አንድ በአንድ ይክፈቱ።

Balancing Redox Reactions in Basic Mediumዘዴ

መቼ እንደሚጠቀሙበት

በ basic ወይም alkaline solution ውስጥ የሚካሄዱትን redox equations በ half-reaction method ለማመጣጠን ይጠቀሙ።

ይጠንቀቁ

መጀመሪያ በ acidic medium እንዳለ ሆኖ በ H+ እና H2O ያመጣጥኑ፤ ከዚያም ለእያንዳንዱ H+ እኩል OH- በሁለቱም በኩል በመደመር H+ እና OH- ን ወደ H2O ይቀይሩ።

ከGrade 12 Chemistry፣ ገጽ 57-135 የተዘጋጀ፤ ከመውጣቱ በፊት ሁለት ጊዜ ተረጋግጧል

Electrolysis Products of Aqueous Solutionsየማጣቀሻ ሠንጠረዥDilute NaCl (inert) · Concentrated NaCl / Brine (inert) · Dilute H_2SO_4 (inert) · +2

Electrolyte እና Electrodes	Cathode Product	Anode Product	ውጤት
Dilute $\text{NaCl}$ (inert)	$\text{H}_2\text{ (g)}$	$\text{O}_2\text{ (g)}$	የውሃ decomposition
Concentrated $\text{NaCl}$ / Brine (inert)	$\text{H}_2\text{ (g)}$	$\text{Cl}_2\text{ (g)}$	$\text{NaOH}$ በ solution ውስጥ ይቀራል
Dilute $\text{H}_2\text{SO}_4$ (inert)	$\text{H}_2\text{ (g)}$	$\text{O}_2\text{ (g)}$	የውሃ decomposition
$\text{CuSO}_4$ ከ inert electrodes (Pt) ጋር	$\text{Cu (s)}$	$\text{O}_2\text{ (g)}$	Solutionኑ acidic ይሆናል ( $\text{H}_2\text{SO}_4$ )
$\text{CuSO}_4$ ከ active $\text{Cu}$ electrodes ጋር	$\text{Cu (s)}$ deposited ይሆናል	$\text{Cu}^{2+}\text{ (aq)}$ dissolved ይሆናል	የ $\text{CuSO}_4$ concentration አይለወጥም

መቼ እንደሚጠቀሙበት

በ aqueous electrolysis ወቅት በ cathode እና anode የሚፈጠሩትን ውጤቶች በ ion concentration እና electrode አይነት ለመወሰን ይጠቀሙ።

ይጠንቀቁ

Active copper anode ሲኖር anode ራሱ ወደ Cu2+ ይቀልጣል እንጂ oxygen gas አይፈጠርም።

ከGrade 12 Chemistry፣ ገጽ 57-135 የተዘጋጀ፤ ከመውጣቱ በፊት ሁለት ጊዜ ተረጋግጧል

Faraday First Law of Electrolysisቀመር

m = \frac{M I t}{n F}

m = \frac{M I t}{n F}

$m$: የተቀመጠው ወይም የተለቀቀው substance mass $\text{g}$
$M$: የ substance molar mass $\text{g\,mol}^{-1}$
$I$: የኤሌክትሪክ ጅረት $\text{A}$
$t$: የኤሌክትሮላይሲስ time $\text{s}$
$n$: valence (በ ion የሚተላለፈው የኤሌክትሮን ቁጥር) $1$
$F$: የፋራዳይ ቋሚ (96,500 C/mol) $\text{C\,mol}^{-1}$

መቼ እንደሚጠቀሙበት

በኤሌክትሮላይሲስ ወቅት የሚፈጠረውን ወይም የሚቀመጠውን የንጥረ ነገር mass በ electric current እና በ time ለማስላት ይጠቀሙ።

ይጠንቀቁ

Time t ወደ ሰከንድ (s) መቀየር አለበት እንጂ በደቂቃ ወይም በሰዓት መተው የለበትም።

ከGrade 12 Chemistry፣ ገጽ 57-135 የተዘጋጀ፤ ከመውጣቱ በፊት ሁለት ጊዜ ተረጋግጧል

Faraday Second Law of Electrolysisቀመር

\frac{m_1}{E_1} = \frac{m_2}{E_2}

\frac{m_1}{E_1} = \frac{m_2}{E_2}

$m_1$: የመጀመሪያው substance mass $\text{g}$
$E_1$: የመጀመሪያው substance equivalent weight (M/n) $\text{g\,eq}^{-1}$
$m_2$: የሁለተኛው substance mass $\text{g}$
$E_2$: የሁለተኛው substance equivalent weight (M/n) $\text{g\,eq}^{-1}$

መቼ እንደሚጠቀሙበት

ተመሳሳይ መጠን ያለው electric charge በ series በተገናኙ ሁለት ወይም ከዚያ በላይ electrolytic cells ውስጥ ሲያልፍ ይጠቀሙ።

ይጠንቀቁ

Equivalent weight E ማለት molar mass ለ valence (n) ሲካፈል ነው። የ valence ቁጥርን ከጨው ፎርሙላ subscript ጋር እንዳያምታቱ።

ከGrade 12 Chemistry፣ ገጽ 57-135 የተዘጋጀ፤ ከመውጣቱ በፊት ሁለት ጊዜ ተረጋግጧል

Metallic versus Electrolytic Conductionየማጣቀሻ ሠንጠረዥየCharge ተሸካሚዎች · የMatter ዝውውር · Chemical change · +1

ባህሪ	Metallic Conduction	Electrolytic Conduction
የCharge ተሸካሚዎች	ተንቀሳቃሽ Delocalized electrons	ተንቀሳቃሽ cations እና anions
የMatter ዝውውር	ምንም የmatter ዝውውር የለም	ትክክለኛ የmatter ዝውውር አለ
Chemical change	ምንም chemical decomposition አይካሄድም	ከchemical decomposition ጋር አብሮ ይካሄዳል
የTemperature ተፅዕኖ	Temperature ሲጨምር conductivity ይቀንሳል	Temperature ሲጨምር conductivity ይጨምራል

መቼ እንደሚጠቀሙበት

የ electric charge በ metals እና በ molten ወይም aqueous electrolytes ውስጥ እንዴት እንደሚተላለፍ ለማወዳደር ይጠቀሙ።

ይጠንቀቁ

የሙቀት መጨመር የ electrolytic conductivity ን በ ionic mobility ምክንያት ሲጨምር፣ የ metallic conductivity ን ግን በንዝረት ምክንያት እንደሚቀንስ ያስታውሱ።

ከGrade 12 Chemistry፣ ገጽ 57-135 የተዘጋጀ፤ ከመውጣቱ በፊት ሁለት ጊዜ ተረጋግጧል

የምዕራፍ 2 የመልመጃ ጥያቄዎች

በዚህ ምዕራፍ ላይ የተጻፉ 10 የምርጫ ጥያቄዎች፣ እያንዳንዳቸው መልሱና ምክንያቱ አላቸው። መልሱን ከመክፈትዎ በፊት ይሞክሩ። ጥያቄዎቹ በእንግሊዝኛ ናቸው።

ጥያቄ 1

In electrochemistry, what happens to an atom or ion during an oxidation process?

A.It loses electrons and its oxidation number increases.
B.It gains electrons and its oxidation number increases.
C.It loses electrons and its oxidation number decreases.
D.It gains electrons and its oxidation number decreases.

መልሱንና ምክንያቱን ያሳዩ

መልስ፦ A It loses electrons and its oxidation number increases.

ምክንያቱ

Oxidation is defined as a process in which an atom or element loses electrons, resulting in an increase in its oxidation number.

ጥያቄ 2

Why does the electrical conductivity of a metallic conductor decrease as the temperature increases?

A.The metal atoms lose their valence electrons to the air.
B.Enhanced thermal vibration of metal atoms disrupts the movement of electrons.
C.The metal melts and stops conducting current.
D.The concentration of mobile positive ions decreases rapidly.

መልሱንና ምክንያቱን ያሳዩ

መልስ፦ B Enhanced thermal vibration of metal atoms disrupts the movement of electrons.

ምክንያቱ

In metallic conduction, conductivity decreases with increasing temperature because the enhanced thermal vibrations of the metal atoms disrupt the smooth movement of free electrons passing through them.

ጥያቄ 3

According to Faraday's first law of electrolysis, the mass of a substance deposited at an electrode is directly proportional to:

A.the volume of the electrolytic container
B.the quantity of electricity passed through the electrolyte
C.the atmospheric pressure above the solution
D.the total mass of the solvent used

መልሱንና ምክንያቱን ያሳዩ

መልስ፦ B the quantity of electricity passed through the electrolyte

ምክንያቱ

Faraday's first law states that the mass (m) of a substance deposited or dissolved at an electrode is directly proportional to the quantity of electricity (Q) passed through the electrolyte (m ∝ Q).

ጥያቄ 4

During the industrial electrolytic refining of copper, which material is used as the cathode?

A.A block of impure copper
B.A thin strip of pure copper
C.A carbon graphite plate
D.An iron nail

መልሱንና ምክንያቱን ያሳዩ

መልስ፦ B A thin strip of pure copper

ምክንያቱ

In electrorefining, the impure copper is made the anode (which dissolves), and a thin strip of pure copper is made the cathode (where pure copper deposits).

ጥያቄ 5

What products are collected at the cathode and anode during the electrolysis of dilute sulfuric acid (H₂SO₄)?

A.Cathode: H2 gas; Anode: O2 gas
B.Cathode: O2 gas; Anode: H2 gas
C.Cathode: SO2 gas; Anode: H2 gas
D.Cathode: H2 gas; Anode: SO3 gas

መልሱንና ምክንያቱን ያሳዩ

መልስ፦ A Cathode: H2 gas; Anode: O2 gas

ምክንያቱ

In dilute H₂SO₄, H⁺ ions are reduced at the cathode to produce H₂ gas, while OH^- ions are preferentially oxidized at the anode to produce O₂ gas and water.

ጥያቄ 6

During the electrolysis of concentrated sodium chloride solution (brine), chlorine gas is produced at the anode instead of oxygen gas. Why does this happen?

A.Sodium ions neutralize the hydroxide ions at the anode.
B.The high concentration of chloride ions favors their discharge over hydroxide ions.
C.Chloride ions have a much lower mobility than water molecules.
D.Hydroxide ions cannot migrate to a positive electrode.

መልሱንና ምክንያቱን ያሳዩ

መልስ፦ B The high concentration of chloride ions favors their discharge over hydroxide ions.

ምክንያቱ

The concentration of an ion affects preferential discharge. In concentrated NaCl (brine), the concentration of Cl^- is much higher than OH^-, causing Cl^- to be discharged preferentially to form Cl₂ gas.

ጥያቄ 7

When balancing the reduction half-reaction MnO₄^- → MnO₂ in an acidic medium, how many electrons (e^-) must be added to the reactant side?

A.1 electron
B.2 electrons
C.3 electrons
D.5 electrons

መልሱንና ምክንያቱን ያሳዩ

መልስ፦ C 3 electrons

ምክንያቱ

Balancing atoms gives: MnO₄^- + 4H⁺ → MnO₂ + 2H₂O. The left side has a charge of +3 and the right side is neutral (0), so 3 electrons (3e^-) must be added to the reactant side.

ጥያቄ 8

A student in Hawassa wants to electroplate an iron key with copper metal. How should the student connect the electrodes to a DC power source?

A.Connect the iron key to the negative terminal (cathode) and the copper plate to the positive terminal (anode).
B.Connect the iron key to the positive terminal (anode) and the copper plate to the negative terminal (cathode).
C.Connect both the iron key and the copper plate to the negative terminal.
D.Connect the iron key to the negative terminal and use a graphite rod as the cathode.

መልሱንና ምክንያቱን ያሳዩ

መልስ፦ A Connect the iron key to the negative terminal (cathode) and the copper plate to the positive terminal (anode).

ምክንያቱ

In electroplating, the object to be plated (the iron key) must be the cathode (negative terminal), and the metal to be deposited (copper plate) must be the anode (positive terminal).

ጥያቄ 9

In a workshop in Addis Ababa, a current of 0.452 A is passed through molten CaCl₂ for 1.5 hours (5,400 seconds). What mass of calcium metal is deposited at the cathode? (Use: 1 F = 96,500 C, molar mass of Ca = 40.08 g/mol)

A.0.507 g
B.1.014 g
C.0.253 g
D.2.440 g

መልሱንና ምክንያቱን ያሳዩ

መልስ፦ A 0.507 g

ምክንያቱ

First, find the total charge: Q = I × t = 0.452 A × 5400 s = 2440.8 C.
Moles of electrons: 2440.8 C / 96,500 C/mol = 0.0253 mol e^-.
Since reduction of Ca²⁺ requires 2 moles of electrons per mole of Ca: mass = (0.0253 / 2) × 40.08 g = 0.507 g.

ጥያቄ 10

Two electrolytic cells containing solutions of CuSO₄ and AgNO₃ are connected in series. When 0.108 g of Ag is deposited in the first cell, what mass of copper is deposited in the second cell? (Equivalent mass of Ag = 108 g/eq, Equivalent mass of Cu = 31.75 g/eq)