Remed Uts Genap Xi IPA-1 Smanio (The Number Of Students Absent 11-20)

1.

Peristiwa hidrolisis tidak terjadi pada larutan ….
- A.
  
  CH3COOK
- B.
  
  CH3COONH4
- C.
  
  (NH4)2SO4
- D.
  
  NH4Cl
- E.
  
  K2SO4
Correct Answer
E. K2SO4

Explanation
Hydrolysis is a chemical reaction where water breaks down a compound into its constituent ions. In the given options, K2SO4 is the only compound that does not undergo hydrolysis. This is because K2SO4 is a salt composed of a strong base (KOH) and a strong acid (H2SO4), which means it dissociates completely in water into K+ and SO4 2- ions without reacting with water to form any new compounds. Therefore, hydrolysis does not occur in K2SO4 solution.

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2.

Garam yang mempunyai pH > 7 dalam larutannya adalah ….
- A.
  
  NaCl
- B.
  
  Na2SO4
- C.
  
  NH4Cl
- D.
  
  K2CO3
- E.
  
  K2SO4
Correct Answer
E. K2SO4

Explanation
Garam yang mempunyai pH > 7 dalam larutannya adalah K2SO4. Ini disebabkan oleh ion sulfat (SO4^2-) yang dapat menerima proton dari air dan membentuk ion hidroksida (OH^-), meningkatkan konsentrasi ion OH^- dalam larutan. Konsentrasi ion OH^- yang tinggi menyebabkan larutan menjadi basa, sehingga memiliki pH > 7.

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3.

Larutan NH3 0,1 M mempunyai pH = 11, pH larutan NH4Cl 0,1 M adalah ….
- A.
  
  11
- B.
  
  9
- C.
  
  7
- D.
  
  5
- E.
  
  3
Correct Answer
D. 5

Explanation
The correct answer is 5. The pH of a solution is a measure of its acidity or alkalinity. A pH of 11 indicates that the solution is basic or alkaline. When NH3 (ammonia) dissolves in water, it forms NH4+ (ammonium) and OH- (hydroxide) ions. NH4Cl is the salt formed by the reaction of NH4+ and Cl- ions. Since NH4+ is the conjugate acid of NH3, it can release H+ ions in solution, making it acidic. Therefore, the pH of a 0.1 M NH4Cl solution would be less than 7, making option 5 the correct answer.

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4.

Dari campuran larutan berikut yang menghasilkan garam terhidrolisis sebagian dan bersifat basa adalah ....
- A.
  
  50 mL 0,5 M HCl + 50 mL 0,5 M NaOH
- B.
  
  50 mL 0,5 M HCl + 50 mL 0,5 M NH3
- C.
  
  50 mL 0,5 M HCl + 100 mL 0,5 M NH3
- D.
  
  50 mL 0,5 M CH3COOH + 50 mL 0,5 M NH3
- E.
  
  50 mL 0,5 M CH3COOH + 50 mL 0,5 M NaOH
Correct Answer
B. 50 mL 0,5 M HCl + 50 mL 0,5 M NH3

Explanation
The correct answer is 50 mL 0,5 M HCl + 50 mL 0,5 M NH3. This is because when hydrochloric acid (HCl) reacts with ammonia (NH3), it forms ammonium chloride (NH4Cl), which is a salt that undergoes partial hydrolysis. The hydrolysis of NH4Cl results in the formation of ammonium ions (NH4+) and hydroxide ions (OH-). Since hydroxide ions are present, the solution will have a basic nature.

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5.

Jika ke dalam 50 mL larutan penyangga dengan pH = 5 ditambahkan 50 mL akuades maka ....
- A.
  
  PH akan naik drastis
- B.
  
  PH akan turun drastis
- C.
  
  PH akan naik sedikt
- D.
  
  PH akan turun sedikit
- E.
  
  PH tidak berubah
Correct Answer
E. PH tidak berubah

Explanation
When 50 mL of distilled water is added to a 50 mL buffer solution with a pH of 5, the pH will not change. This is because a buffer solution is able to resist changes in pH when small amounts of acid or base are added. In this case, the buffer solution is able to maintain its pH of 5 even after the addition of distilled water.

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6.

Sebanyak 200 mL NH4OH 0,4 M (Kb = 10^–5 M) dicampurkan dengan 200 mL HCl 0,2 M membentuk larutan penyangga dengan pH ....
- A.
  
  5
- B.
  
  9
- C.
  
  10
- D.
  
  11
- E.
  
  12
Correct Answer
A. 5

Explanation
When NH4OH and HCl are mixed together, they react to form NH4Cl, which is a salt. NH4Cl is the conjugate acid of NH4OH, and it can act as a weak acid in solution. Since NH4Cl is a weak acid, it will partially dissociate in water, releasing H+ ions. These H+ ions will then react with the OH- ions from the dissociation of NH4OH, forming water. This reaction helps to buffer the pH of the solution. The pH of a buffer solution can be calculated using the Henderson-Hasselbalch equation, which is pH = pKa + log([A-]/[HA]). In this case, NH4Cl is the conjugate acid (HA) and NH3 is the conjugate base (A-). The pKa of NH4Cl can be calculated using the equation pKa = -log(Ka), where Ka is the acid dissociation constant. Since NH4Cl is a salt of a weak acid and a strong base, the pKa can be approximated as the pKw - pKb, where pKw is the ion product of water (14) and pKb is the pKa of the base (NH4OH). Therefore, pKa = 14 - 5 = 9. Plugging this value into the Henderson-Hasselbalch equation, we get pH = 9 + log([NH3]/[NH4+]). Since the concentration of NH3 and NH4+ are equal in the buffer solution, the ratio [NH3]/[NH4+] is 1, and log(1) = 0. Therefore, the pH of the buffer solution is 9 + 0 = 9.

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7.

Larutan penyangga merupakan campuran dari ....
- A.
  
  Asam lemah dan basa lemah
- B.
  
  Asam lemah dan basa kuat
- C.
  
  Asam kuat dan garamnya
- D.
  
  Asam kuat dan basa kuat
- E.
  
  Asam lemah dan garamnya
Correct Answer
E. Asam lemah dan garamnya

Explanation
Larutan penyangga terbentuk dari asam lemah dan garamnya. Asam lemah memberikan ion H+ sedangkan garamnya memberikan ion konjugat yang dapat menerima ion H+. Ini memungkinkan larutan penyangga untuk menjaga kestabilan pH ketika asam atau basa ditambahkan ke dalamnya. Asam kuat dan basa kuat tidak dapat membentuk larutan penyangga karena mereka sepenuhnya terionisasi dalam air dan tidak ada ion yang tersedia untuk menjaga kestabilan pH.

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8.
- A.
  
  3,5 dan 6
- B.
  
  3,4 dan 6
- C.
  
  2,4 dan 6
- D.
  
  1,3 dan 6
- E.
  
  1,2 dan 6
Correct Answer
D. 1,3 dan 6
9.

Besarnya pH larutan 0,74 gram Ca(OH)2 (Ar Ca = 40, O = 16, dan H = 1) dalam 500 mL larutan adalah … .
- A.
  
  2 – log 4
- B.
  
  2 + log 4
- C.
  
  11 + log 4
- D.
  
  12 – log 4
- E.
  
  12 + log 4
Correct Answer
E. 12 + log 4

Explanation
The given expression is 12 + log 4. The logarithm of 4 is approximately 0.602, so when we add 12 to it, the result is approximately 12.602. Therefore, the answer is 12 + log 4.

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10.

Jika 0,56 gram logam A direaksikan dengan larutan HCl akan diperoleh gas H2 sebanyak 0,005 mol dan larutan ACl2. Massa atom relatif logam A adalah ….
- A.
  
  7
- B.
  
  14
- C.
  
  28
- D.
  
  56
- E.
  
  112
Correct Answer
D. 56

Explanation
When 0.56 grams of metal A reacts with HCl solution, it produces 0.005 mol of H2 gas and a solution of ACl2. The relative atomic mass of metal A can be calculated by dividing the mass of metal A (0.56 grams) by the number of moles of metal A (0.005 mol). This gives a value of 112 grams/mol. However, the question asks for the mass of the atom, not the molar mass. Since 1 mol of metal A contains 6.022 x 10^23 atoms, the mass of one atom of metal A can be calculated by dividing the molar mass by Avogadro's number. Therefore, the mass of one atom of metal A is 112 grams/mol divided by 6.022 x 10^23, which is approximately 1.86 x 10^-22 grams. The closest option to this value is 56, which is the correct answer.

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Remed Uts Genap Xi IPA-1 Smanio (The Number Of Students Absent 11-20)

Peristiwa hidrolisis tidak terjadi pada larutan ….

Garam yang mempunyai pH > 7 dalam larutannya adalah ….

Larutan NH3 0,1 M mempunyai pH = 11, pH larutan NH4Cl 0,1 M adalah ….

Dari campuran larutan berikut yang menghasilkan garam terhidrolisis sebagian dan bersifat basa adalah ....

Jika ke dalam 50 mL larutan penyangga dengan pH = 5 ditambahkan 50 mL akuades maka ....

Sebanyak 200 mL NH4OH 0,4 M (Kb = 10–5 M) dicampurkan dengan 200 mL HCl 0,2 M membentuk larutan penyangga dengan pH ....

Larutan penyangga merupakan campuran dari ....

Besarnya pH larutan 0,74 gram Ca(OH)2 (Ar Ca = 40, O = 16, dan H = 1) dalam 500 mL larutan adalah … .

Jika 0,56 gram logam A direaksikan dengan larutan HCl akan diperoleh gas H2 sebanyak 0,005 mol dan larutan ACl2. Massa atom relatif logam A adalah ….

Sebanyak 200 mL NH4OH 0,4 M (Kb = 10^–5 M) dicampurkan dengan 200 mL HCl 0,2 M membentuk larutan penyangga dengan pH ....