የ12ኛ ክፍል ውጤት ወጥቷል፤ ውጤትዎን የሚያዩበት መንገድ

የምዕራፍ ማስታወሻዎችና የመልመጃ ጥያቄዎች

የ12ኛ ክፍል ኬሚስትሪ ምዕራፍ 1፦ የአሲድ እና ቤዝ ሚዛን

በዚህ ገጽ ያለው ሁሉ ለ12ኛ ክፍል የኬሚስትሪ መፅሐፍ ምዕራፍ 1 ነው፦ ምዕራፉ የሚሸፍነው፣ አጭር ማስታወሻዎቹ፣ የመልመጃ ጥያቄዎች ከመልሶቻቸው ጋር፣ እና ቪዲዮ ባለበት የትምህርቱ ቪዲዮ።

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የምዕራፍ 1 የመልመጃ ጥያቄዎች
3–56
የምዕራፍ 1 የመፅሐፍ ገጾች

ምዕራፍ 1 የሚሸፍነው

  1. 1.Acid-Base Concepts
  2. 2.Arrhenius Concept of Acids and Bases
  3. 3.Brønsted-Lowry Concept of Acids and Bases
  4. 4.Lewis Concept of Acids and Bases
  5. 5.Ionic Equlibria of Week Acids and Bases
  6. 6.Ionization of Water
  7. 7.Measures of the Strength of acids and Bases in Aque
  8. 8.Common Ion Effect and Buffer Solution
  9. 9.The Common Ion Effect
  10. 10.Buffer Solutions
  11. 11.Hydrolysis of Salts
  12. 12.Hydrolysis of Salts of Strong Acids and Strong Bases
  13. 13.Hydrolysis of Salts of Weak Acids and Strong Bases
  14. 14.Hydrolysis of Salts of Strong Acids and Weak Bases
  15. 15.Hydrolysis of Salts of Weak Acids and Week Bases
  16. 16.Acid-Base Indicators and Titrations
  17. 17.Acid-Base Indicators
  18. 18.Equivalents of Acids and Bases
  19. 19.Acid-Base Titrations

የምዕራፍ 1 አጭር ማስታወሻዎች

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

pH=pKa+log⁡([A−][HA])\text{pH} = \text{p}K_a + \log\left(\frac{[\text{A}^-]}{[\text{HA}]}\right)
pH\text{pH}
የbuffer መፍትሄ pHdimensionlessdimensionless
pKa\text{p}K_a
የacid dissociation constant ኔጌቲቭ ሎጋሪዝምdimensionlessdimensionless
[A−][\text{A}^-]
የconjugate base የሞላር concentrationmol L−1\text{mol}\,\text{L}^{-1}
[HA][\text{HA}]
የweak acid የሞላር concentrationmol L−1\text{mol}\,\text{L}^{-1}

መቼ እንደሚጠቀሙበት

ከweak acid እና ከconjugate base የተዘጋጀን የbuffer መፍትሄ pH ለማስላት ይጠቀሙበት።

ይጠንቀቁ

በሎጋሪዝም ውስጥ ያለው ጥምርታ ላይ conjugate base ከአሃዝ እና weak acid ከታችኛው ክፍል መሆን አለበት።

ከGrade 12 Chemistry፣ ገጽ 3-56 የተዘጋጀ፤ ከመውጣቱ በፊት ሁለት ጊዜ ተረጋግጧል

Kw=[H3O+][OH−]=1.0×10−14K_w = [\text{H}_3\text{O}^+][\text{OH}^-] = 1.0 \times 10^{-14}
KwK_w
በ25 °C ላይ የውሃ ion product constantmol2 L−2\text{mol}^2\,\text{L}^{-2}
[H3O+][\text{H}_3\text{O}^+]
የhydronium ion concentrationmol L−1\text{mol}\,\text{L}^{-1}
[OH−][\text{OH}^-]
የhydroxide ion concentrationmol L−1\text{mol}\,\text{L}^{-1}

መቼ እንደሚጠቀሙበት

በ25 °C ላይ በhydronium እና hydroxide ion concentration መካከል ለመቀያየር ወይም pH እና pOH ለማስላት ይጠቀሙበት።

ይጠንቀቁ

የ1.0 ሲባዛ በ10^-14 ዋጋ የሚሰራው በ25 °C ላይ ብቻ ነው፣ የሙቀት መጠን ሲቀየር ዋጋው ይለወጣል።

ከGrade 12 Chemistry፣ ገጽ 3-56 የተዘጋጀ፤ ከመውጣቱ በፊት ሁለት ጊዜ ተረጋግጧል

መቼ እንደሚጠቀሙበት

ለደካማ acids እና bases ሚዛናዊ ስሌት ሲሰራ x ከመጀመሪያ concentration ቀንሶ የመተውን ማቅለያ ሲጠቀሙ።

ይጠንቀቁ

የተሰላው x ከመጀመሪያው concentration ከ5 ፐርሰንት በላይ ከሆነ ማቅለያው አይሰራም፤ በquadratic formula መስራት ግዴታ ነው።

ከGrade 12 Chemistry፣ ገጽ 3-56 የተዘጋጀ፤ ከመውጣቱ በፊት ሁለት ጊዜ ተረጋግጧል

መነሻ Acidመነሻ Baseየመፍትሄው ባህሪየpH መጠን በ25 °C
StrongStrongNeutralpH=7\text{pH} = 7
WeakStrongBasicpH>7\text{pH} > 7
StrongWeakAcidicpH<7\text{pH} < 7
WeakWeakDepends on KaK_a and KbK_bKa>Kb⇒pH<7K_a > K_b \Rightarrow \text{pH} < 7

መቼ እንደሚጠቀሙበት

የጨው መፍትሄ acidic, basic ወይም neutral መሆኑን ለመወሰን ይጠቀሙበት።

ይጠንቀቁ

ለደካማ acid እና ደካማ base ጨዎች የመፍትሄውን ባህሪ ለመወሰን የcation Ka እና የanion Kb ማወዳደር ያስፈልጋል።

ከGrade 12 Chemistry፣ ገጽ 3-56 የተዘጋጀ፤ ከመውጣቱ በፊት ሁለት ጊዜ ተረጋግጧል

የምዕራፍ 1 የመልመጃ ጥያቄዎች

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

ጥያቄ 1

Under the Brønsted Lowry concept, an acid is a substance that

  1. A.donates a proton
  2. B.accepts a proton
  3. C.accepts an electron pair
  4. D.produces hydroxide ions in water
መልሱንና ምክንያቱን ያሳዩ

መልስ፦ A donates a proton

ምክንያቱ

Brønsted Lowry defines an acid as a proton donor and a base as a proton acceptor. Option C is the Lewis definition of an acid and option D is the Arrhenius definition of a base.

ጥያቄ 2

What is the conjugate base of H₂SO₄?

  1. A.SO₄²⁻
  2. B.HSO₄⁻
  3. C.H₃SO₄⁺
  4. D.H₂SO₃
መልሱንና ምክንያቱን ያሳዩ

መልስ፦ B HSO₄⁻

ምክንያቱ

A conjugate pair differs by exactly one proton. Removing one H⁺ from H₂SO₄ leaves HSO₄⁻. Option A is the conjugate base of HSO₄⁻, so it is two protons away and one step too far. Option C is the conjugate acid.

ጥያቄ 3

What is the pH of a 0.001 mol/L solution of HCl?

  1. A.1
  2. B.2
  3. C.3
  4. D.11
መልሱንና ምክንያቱን ያሳዩ

መልስ፦ C 3

ምክንያቱ

HCl is a strong acid and ionizes completely, so the hydrogen ion concentration is 0.001, which is 10⁻³. pH is the negative logarithm of that, so pH = 3. Option D is the pOH, and pH plus pOH equals 14.

ጥያቄ 4

BF₃ has no proton to give, yet it is classed as an acid. Under which concept, and why?

  1. A.Arrhenius, because it releases hydrogen ions
  2. B.Brønsted Lowry, because it donates a proton
  3. C.Lewis, because it accepts a pair of electrons
  4. D.It cannot be classed as an acid at all
መልሱንና ምክንያቱን ያሳዩ

መልስ፦ C Lewis, because it accepts a pair of electrons

ምክንያቱ

Boron in BF₃ has only six electrons around it, so it readily accepts an electron pair. That is the Lewis definition of an acid, and it is exactly why the Lewis concept is the broadest of the three.

ጥያቄ 5

The Ka of a weak acid is 2.0 x 10⁻⁵. What is the Kb of its conjugate base?

  1. A.2.0 x 10⁻⁹
  2. B.5.0 x 10⁻¹⁰
  3. C.2.0 x 10⁻¹⁹
  4. D.5.0 x 10⁻⁵
መልሱንና ምክንያቱን ያሳዩ

መልስ፦ B 5.0 x 10⁻¹⁰

ምክንያቱ

For a conjugate pair, Ka multiplied by Kb equals Kw. So Kb = 1.0 x 10⁻¹⁴ divided by 2.0 x 10⁻⁵ = 5.0 x 10⁻¹⁰. Option C comes from multiplying the two values instead of dividing.

ጥያቄ 6

A buffer contains a weak acid and its salt at equal concentrations. Its pH is

  1. A.7, because the two cancel out
  2. B.equal to the pKa of the acid
  3. C.equal to the pKb of the salt
  4. D.impossible to work out without the volumes
መልሱንና ምክንያቱን ያሳዩ

መልስ፦ B equal to the pKa of the acid

ምክንያቱ

The Henderson Hasselbalch equation gives pH = pKa + log([salt]/[acid]). When the two concentrations are equal the ratio is 1 and log 1 is zero, so pH equals pKa. This is also the point at which the buffer resists change most effectively.

ጥያቄ 7

An aqueous solution of ammonium chloride is

  1. A.acidic, because the ammonium ion hydrolyses
  2. B.basic, because the chloride ion hydrolyses
  3. C.neutral, because it is a salt
  4. D.basic, because ammonia is a base
መልሱንና ምክንያቱን ያሳዩ

መልስ፦ A acidic, because the ammonium ion hydrolyses

ምክንያቱ

Ammonium chloride comes from a strong acid, HCl, and a weak base, ammonia. The stronger parent decides, so the solution is acidic. The ammonium ion reacts with water and releases hydronium ions, while the chloride ion is too weak a base to do anything.

ጥያቄ 8

Which indicator is most suitable for titrating acetic acid with sodium hydroxide?

  1. A.Methyl orange
  2. B.Phenolphthalein
  3. C.Litmus
  4. D.Any of them works equally well
መልሱንና ምክንያቱን ያሳዩ

መልስ፦ B Phenolphthalein

ምክንያቱ

A weak acid with a strong base has its equivalence point above pH 7, because the salt formed hydrolyses to give a basic solution. Phenolphthalein changes between pH 8.3 and 10.0, which sits inside the steep part of that curve. Methyl orange would change far too early.

ጥያቄ 9

Adding sodium acetate to a solution of acetic acid causes the ionization of the acid to decrease. This is

  1. A.the common ion effect
  2. B.hydrolysis
  3. C.neutralization
  4. D.titration
መልሱንና ምክንያቱን ያሳዩ

መልስ፦ A the common ion effect

ምክንያቱ

Sodium acetate supplies acetate ions, which the acid already produces. By Le Chatelier's principle the extra acetate pushes the ionization equilibrium back to the left, so fewer hydronium ions form. That suppression is the common ion effect, and it is the basis of how a buffer is made.

ጥያቄ 10

Water at 50 degrees Celsius has a pH slightly below 7. What does this tell you?

  1. A.The water has become acidic
  2. B.The water is still neutral, because Kw rises with temperature
  3. C.The measurement must be wrong
  4. D.The water has dissolved carbon dioxide
መልሱንና ምክንያቱን ያሳዩ

መልስ፦ B The water is still neutral, because Kw rises with temperature

ምክንያቱ

Neutral means the hydronium and hydroxide concentrations are equal, not that the pH reads exactly 7. Kw increases with temperature, so both concentrations rise and the neutral pH falls below 7 while remaining neutral. The value 7 only applies at 25 degrees Celsius.

መተግበሪያው በዚህ ምዕራፍ ላይ 12 ጥያቄዎች አሉት፤ እየሠሩ ያርምዎታል። እዚህ ያሉት የመጀመሪያዎቹ 10 ናቸው።

የምዕራፍ 1 የመፅሐፍ ገጾች

ምዕራፍ 1 በየትምህርት ሚኒስቴር እትም ከገጽ 3 እስከ ገጽ 56 ይደርሳል።

የትምህርት ሚኒስቴር እትም, እንግሊዝኛ, 298 ገጾች

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ሁሉም የ12ኛ ክፍል ኬሚስትሪ አጭር ማስታወሻዎች

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