Yaadannoo boqonnaa fi gaaffii shaakalaa
Wanti fuula kana irra jiru hundi boqonnaa 1 kitaaba Keemistirii kutaa 12 tiif: wanta boqonnaan haguugu, yaadannoo gabaabaa, gaaffii shaakalaa deebii isaanii waliin, fi viidiyoo barnootaa bakka jirutti.
Kaardiiwwan fuula Keemistirii kutaa 12 irratti boqonnaa kana jala galmaa'an. Tokko tokkoon bani.
Yoom akka itti fayyadamtu
pH furmaata baafarii kan weak acid fi conjugate base irraa tolfame shallaguuf fayyadamaa.
Of eeggadhu
Reeshoo logaritmii keessatti concentration conjugate base lakkooftuu fi weak acid gedaantoo ta'uu qaba.
Grade 12 Chemistry, fuula 3-56 irraa qophaa'e; osoo hin ba'in dura yeroo lama mirkanaa'e
Yoom akka itti fayyadamtu
Concentration hydronium fi hydroxide walitti jijjiiruuf ykn 25 °C irratti pH fi pOH shallaguuf fayyadamaa.
Of eeggadhu
Gatiin 1.0 baay'isuu 10^-14 kan hojjatu 25 °C qofa irratti, teempireecheraan walqabatee ni jijjiirama.
Grade 12 Chemistry, fuula 3-56 irraa qophaa'e; osoo hin ba'in dura yeroo lama mirkanaa'e
Yoom akka itti fayyadamtu
Hisaaba walgitiinsa weak acids fi weak bases yeroo x concentration jalqabaa irraa hir'isuun salphistan.
Of eeggadhu
Gatiin x concentration jalqabaa irraa parsantii 5 ol yoo ta'e tilmaamni sun hin hojjatu, formula quadratic fayyadamuun dirqama.
Grade 12 Chemistry, fuula 3-56 irraa qophaa'e; osoo hin ba'in dura yeroo lama mirkanaa'e
| Parent Acid | Parent Base | Amala Furmaataa | Hangi pH 25 °C irratti |
|---|---|---|---|
| Strong | Strong | Neutral | |
| Weak | Strong | Basic | |
| Strong | Weak | Acidic | |
| Weak | Weak | Depends on and |
Yoom akka itti fayyadamtu
Furmaanni soogidda bishaan keessa baqe acidic, basic ykn neutral ta'uu isaa tilmaamuuf fayyadamaa.
Of eeggadhu
Soogidda weak acid fi weak base irraa dhufeef amala murteessuuf Ka kan cation fi Kb kan anion walbira qabuun barbaachisaadha.
Grade 12 Chemistry, fuula 3-56 irraa qophaa'e; osoo hin ba'in dura yeroo lama mirkanaa'e
Gaaffii filannoo 10 boqonnaa kana irratti barreeffaman, tokkoon tokkoon isaanii deebii fi sababa qabu. Deebii banuu dura yaali. Gaaffiin kun Ingiliffaa tiin.
Gaaffii 1
Under the Brønsted Lowry concept, an acid is a substance that
Deebii: A donates a proton
Sababa
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.
Gaaffii 2
What is the conjugate base of H₂SO₄?
Deebii: B HSO₄⁻
Sababa
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.
Gaaffii 3
What is the pH of a 0.001 mol/L solution of HCl?
Deebii: C 3
Sababa
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.
Gaaffii 4
BF₃ has no proton to give, yet it is classed as an acid. Under which concept, and why?
Deebii: C Lewis, because it accepts a pair of electrons
Sababa
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.
Gaaffii 5
The Ka of a weak acid is 2.0 x 10⁻⁵. What is the Kb of its conjugate base?
Deebii: B 5.0 x 10⁻¹⁰
Sababa
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.
Gaaffii 6
A buffer contains a weak acid and its salt at equal concentrations. Its pH is
Deebii: B equal to the pKa of the acid
Sababa
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.
Gaaffii 7
An aqueous solution of ammonium chloride is
Deebii: A acidic, because the ammonium ion hydrolyses
Sababa
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.
Gaaffii 8
Which indicator is most suitable for titrating acetic acid with sodium hydroxide?
Deebii: B Phenolphthalein
Sababa
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.
Gaaffii 9
Adding sodium acetate to a solution of acetic acid causes the ionization of the acid to decrease. This is
Deebii: A the common ion effect
Sababa
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.
Gaaffii 10
Water at 50 degrees Celsius has a pH slightly below 7. What does this tell you?
Deebii: B The water is still neutral, because Kw rises with temperature
Sababa
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.
Appiin boqonnaa kana irratti gaaffii 12 qaba; utuu hojjettuu ni sirreessa. Kan asii jiran 10 jalqabaa ti.
Boqonnaan 1 Maxxansa Ministeera Barnootaa keessatti fuula 3 hanga fuula 56 ti.
Maxxansa Ministeera Barnootaa, Ingiliffaa, Fuula 298
Temari boqonnaa kana gara shaakala yeroon daangeffametti jijjiira; utuu hojjettuu ni sirreessa; wanti si hin galinis barsiisaa AI tiin ni ibsama.
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