Uts Kimia Kelas Xii.IPA.1,2,3,4
Questions and Answers
- 1.
Jika ke dalam 90 gram air (Mr= 18) dilarutkan 15 gram asam cuka ( Mr = 60) maka fraksi mol zat terlarut dan pelarutnya berturut-turut adalah...
- A.
0,95 dan 0,05
- B.
0,75 dan 0,25
- C.
0,85 dan 0,15
- D.
0,01 dan 0,99
- E.
0,05 dan 0,95
Correct Answer
E. 0,05 dan 0,95Explanation
The correct answer is 0,05 dan 0,95. This means that the solute (asam cuka) has a mole fraction of 0,05 and the solvent (air) has a mole fraction of 0,95. Mole fraction is the ratio of moles of a component to the total moles in a solution. In this case, the moles of asam cuka is 15 g / 60 g/mol = 0,25 mol and the moles of air is 90 g / 18 g/mol = 5 mol. The total moles in the solution is 0,25 mol + 5 mol = 5,25 mol. Therefore, the mole fraction of asam cuka is 0,25 mol / 5,25 mol = 0,05 and the mole fraction of air is 5 mol / 5,25 mol = 0,95.Rate this question:
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- 2.
Molalitas larutan 20 % etanol (Mr=46) adalah....
- A.
6,4 m
- B.
5,4 m
- C.
4,4 m
- D.
3,4 m
- E.
0,4 m
Correct Answer
B. 5,4 mExplanation
The molality of a solution is calculated by dividing the moles of solute by the mass of the solvent in kilograms. In this case, the solution is 20% ethanol, so there is 20 grams of ethanol in 100 grams of solution. To find the moles of ethanol, we divide the mass by the molar mass of ethanol (46 g/mol). This gives us 20/46 = 0.43 moles of ethanol. The mass of the solvent is 100 - 20 = 80 grams. Converting this to kilograms gives us 0.08 kg. Finally, we divide the moles of ethanol by the mass of the solvent to get the molality: 0.43/0.08 = 5.4 m.Rate this question:
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- 3.
Di antara kelima larutan 0,1 m di bawah ini yang mempunyai titik didih paling tinggi pada tekanan 1 atm adalah . . . .
- A.
NaCl
- B.
KCl
- C.
MgCl2
- D.
Gula
- E.
Urea
Correct Answer
C. MgCl2Explanation
MgCl2 is the correct answer because it is a compound that consists of a metal (magnesium) and a non-metal (chlorine). Ionic compounds like MgCl2 have higher boiling points compared to covalent compounds like NaCl, KCl, and urea. This is because ionic compounds have stronger intermolecular forces of attraction due to the presence of charged ions, which require more energy to break and convert into a gaseous state. Gula (sugar) is a covalent compound and would have a lower boiling point compared to MgCl2.Rate this question:
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- 4.
Tekanan osmotik larutan nonelektrolit 0,100 M pada temperatur 0°C adalah . . . atm( R=0,082)
- A.
0,224
- B.
2,24
- C.
22,4
- D.
224
- E.
2240
Correct Answer
B. 2,24Explanation
The osmotic pressure of a solution is determined by the concentration of solute particles in the solution. In this case, the solution is a non-electrolyte with a concentration of 0.100 M. Osmotic pressure can be calculated using the formula π = nRT, where π is the osmotic pressure, n is the number of moles of solute, R is the ideal gas constant, and T is the temperature in Kelvin. Given that R is 0.082 and the temperature is 0°C (which is equivalent to 273 K), we can calculate the osmotic pressure as follows: π = (0.100 mol/L)(0.082 atm·L/mol·K)(273 K) = 2.24 atm. Therefore, the correct answer is 2.24 atm.Rate this question:
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- 5.
Titik didih larutan NaCl 0,2 m memiliki titik didih sebesar …….°C ( Kb = 0,52)
- A.
0,208
- B.
0,52
- C.
2,08
- D.
100,208
- E.
100,52
Correct Answer
D. 100,208Explanation
The boiling point of a solution is determined by the concentration of solute particles in the solution. In this question, the concentration of NaCl is given as 0.2 m. The boiling point elevation constant (Kb) for NaCl is given as 0.52. Using the formula ΔTb = Kb * m, where ΔTb is the boiling point elevation and m is the molality of the solution, we can calculate the boiling point elevation. Plugging in the values, we get ΔTb = 0.52 * 0.2 = 0.104. Adding this to the boiling point of pure water (100°C), we get the boiling point of the NaCl solution as 100.104 or approximately 100.208°C.Rate this question:
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- 6.
Larutan isotonis adalah larutan yang memiliki ….
- A.
Titik didih sama
- B.
Titik beku sama
- C.
Tekanan osmotik sama
- D.
Konsentrasi sama
- E.
Tekanan uap sama
Correct Answer
C. Tekanan osmotik samaExplanation
Larutan isotonis adalah larutan yang memiliki tekanan osmotik sama. Osmosis adalah pergerakan pelarut dari daerah yang memiliki konsentrasi rendah ke daerah yang memiliki konsentrasi tinggi melalui sebuah membran semipermeabel. Dalam larutan isotonis, konsentrasi zat terlarut di dalam larutan sama dengan konsentrasi zat terlarut di dalam sel. Hal ini menyebabkan tekanan osmotik di dalam larutan isotonis menjadi sama dengan tekanan osmotik di dalam sel.Rate this question:
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- 7.
Larutan urea 3 m akan membeku pada suhu …. ( kf = 1,86)
- A.
-5,58
- B.
-2,79
- C.
-2,5
- D.
-1,86
- E.
-1,68
Correct Answer
A. -5,58Explanation
The correct answer is -5,58. Urea is a solute that lowers the freezing point of a solution. The formula to calculate the freezing point depression is ΔT = kf * m, where ΔT is the change in temperature, kf is the cryoscopic constant, and m is the molality of the solution. In this case, the molality is 3 m. By substituting the values into the formula, we get ΔT = 1,86 * 3 = 5,58. Since the freezing point depression is negative, the freezing point of the urea solution will be lower than the freezing point of pure solvent, resulting in a freezing point of -5,58.Rate this question:
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- 8.
Larutan memiliki … dibandingkan pelarutnya.
- A.
Tekanan uap yang lebih tinggi
- B.
Titik didih lebih tinggi
- C.
Titik beku yang lebih tinggi
- D.
Tekanan osmotik yang sama
- E.
Konsentrasi yang lebih rendah
Correct Answer
B. Titik didih lebih tinggiExplanation
The statement suggests that the solution has a higher boiling point compared to the solvent. This can be explained by the phenomenon of boiling point elevation, which occurs when a solute is added to a solvent. The presence of the solute particles disrupts the intermolecular forces between the solvent molecules, making it more difficult for them to escape from the liquid phase and enter the gas phase. As a result, a higher temperature is required to reach the boiling point and convert the liquid into a gas. Therefore, the correct answer is "titik didih lebih tinggi" (higher boiling point).Rate this question:
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- 9.
Diketahui reaksi redoks: aCu + bH+ + cNO3– → dCu2+ + H2O + eNO2.Setelah reaksi disetarakan maka harga a, b, c, d, dan e berturut-turut . . . .
- A.
1 – 4 – 2 – 1 – 2
- B.
2 – 1 – 4 – 1 – 2
- C.
1 – 2 – 4 – 2 – 1
- D.
1 – 4 – 1 – 2 – 1
- E.
2 – 1 – 1 – 2 – 1
Correct Answer
A. 1 – 4 – 2 – 1 – 2Explanation
The balanced redox reaction can be written as: 2Cu + 4H+ + 2NO3- -> Cu2+ + 2H2O + 2NO2. This means that for every 2 moles of Cu, 4 moles of H+ and 2 moles of NO3- are required. The reaction produces 1 mole of Cu2+, 2 moles of H2O, and 2 moles of NO2. Therefore, the correct answer is 1 – 4 – 2 – 1 – 2.Rate this question:
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- 10.
Bahan yang digunakan senbagai elektroda pada sel aki adalah….
- A.
Pt dan C
- B.
Zn dan C
- C.
Pt dan PbO2
- D.
Zn dan Cu
- E.
Pb dan PbO2
Correct Answer
E. Pb dan PbO2Explanation
The correct answer is Pb dan PbO2. This is because lead (Pb) and lead dioxide (PbO2) are commonly used as electrodes in lead-acid batteries. Lead acts as the negative electrode (anode) while lead dioxide acts as the positive electrode (cathode). These electrodes undergo chemical reactions during the charging and discharging of the battery, allowing for the flow of electrons and the storage of electrical energy.Rate this question:
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- 11.
Logam yang dapat memberikan perlindungan katodik pada besi (Fe) adalah ….
- A.
Ni
- B.
Sn
- C.
Pb
- D.
Mg
- E.
Cu
Correct Answer
D. MgExplanation
Mg (magnesium) can provide cathodic protection to iron (Fe) because it has a higher electronegativity than iron. This means that magnesium will act as an anode and sacrifice itself to protect the iron from corrosion. Magnesium will oxidize and release electrons, which will then flow to the iron, preventing it from corroding.Rate this question:
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- 12.
Pada reaksi redoks berikut, Mg + H2SO4 → MgSO4 + H2 ,Oksidator reaksi tersebut adalah. . . .
- A.
Mg
- B.
H2SO4
- C.
MgSO4
- D.
H2
- E.
2H+
Correct Answer
B. H2SO4Explanation
In the given redox reaction, Mg is being oxidized from its elemental state to Mg2+ in MgSO4. The oxidizing agent is the species that causes the oxidation, which in this case is H2SO4. H2SO4 donates H+ ions, which react with Mg to form Mg2+ ions, resulting in the oxidation of Mg. Therefore, H2SO4 is the oxidizing agent in this reaction.Rate this question:
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- 13.
Pada reaksi berikut ini.Fe2O3 + 2Al → Al2O3 + 2FeSenyawa yang mengalami reaksi oksidasi adalah….
- A.
Al
- B.
Fe2O3
- C.
Al2O3
- D.
Fe
- E.
Tidak satu pun karena bukan reaksi redoks
Correct Answer
A. AlExplanation
In the given reaction, Fe2O3 + 2Al → Al2O3 + 2Fe, aluminum (Al) undergoes oxidation. This can be determined by looking at the changes in oxidation states of the elements involved. In the reactants, aluminum has an oxidation state of 0, while in the product Al2O3, aluminum has an oxidation state of +3. Since the oxidation state of aluminum increases from 0 to +3, it is undergoing oxidation. Therefore, the correct answer is Al.Rate this question:
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- 14.
Zat yang bertindak sebagai pereduksi (reduktor) pada reaksi redoks berikut ini: HNO3 + H2S → NO + S + H2O adalah ….
- A.
HNO3
- B.
S
- C.
NO
- D.
H2S
- E.
H2O
Correct Answer
D. H2SExplanation
In the given redox reaction, H2S is acting as the reducing agent or reductor. This is because it is being oxidized, losing electrons and undergoing a decrease in oxidation state from -2 to 0. It is donating its electrons to the NO3- ion, which is being reduced and undergoing an increase in oxidation state from +5 to +2. Therefore, H2S is the species that is causing the reduction to occur in this reaction.Rate this question:
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- 15.
Diketahui : Zn2+ / Zn = –0,76 V; Pb2+ / Pb = –0,13 V; Cu2+ / Cu = +0,34 V; Ag+ / Ag = +0,80 V.Reaksi sel yang menghasilkan potensial terbesar adalah ….
- A.
Zn(s) / Zn2+(aq) // Cu2+(aq) / Cu(s)
- B.
Fe(s) / Fe2+(aq) // Ag2+(aq) / Ag(s)
- C.
Zn(s) / Zn2+(aq) // Ag2+(aq) / Ag(s)
- D.
Pb(s) / Pb2+(aq) // Cu2+(aq) / Cu(s)
- E.
Zn(s) / Zn2+(aq) // Pb2+(aq) / Pb(s)
Correct Answer
C. Zn(s) / Zn2+(aq) // Ag2+(aq) / Ag(s)Explanation
The given answer, "Zn(s) / Zn2+(aq) // Ag2+(aq) / Ag(s)", is the correct choice because it involves the combination of the two half-cell reactions with the highest individual potentials. The half-cell reaction for Zn2+ / Zn has a potential of -0.76 V, and the half-cell reaction for Ag+ / Ag has a potential of +0.80 V. When these two reactions are combined, the overall cell potential will be the sum of the individual potentials, which is 0.80 V - 0.76 V = 0.04 V. This is the highest potential among the given options, indicating that it will produce the largest potential difference or voltage.Rate this question:
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- 16.
Berdasarkan deret Volta, reduktor yang lebih kuat dari Mn adalah ….
- A.
Zn
- B.
Mg
- C.
Fe
- D.
Ni
- E.
Pb
Correct Answer
B. MgExplanation
Based on the Voltaic series, the element that is a stronger reducing agent than Mn is Mg. The Voltaic series is a list of metals arranged in order of their tendency to lose electrons and undergo oxidation. The higher up an element is in the series, the more easily it loses electrons and acts as a reducing agent. Since Mg is higher up in the series than Mn, it has a greater tendency to lose electrons and is therefore a stronger reducing agent.Rate this question:
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- 17.
Jika garam CuSO4 dielektrolisis dengan elektrode Zn, pada katode akan terbentuk ….
- A.
Gas oksigen
- B.
Gas hidrogen
- C.
Ion hdroksida
- D.
Logam tembaga
- E.
Uap air
Correct Answer
D. Logam tembagaExplanation
When CuSO4 is electrolyzed with a Zn electrode, copper metal will be formed at the cathode. This is because during electrolysis, positive ions are attracted to the negative electrode (cathode), where they gain electrons and are reduced. In this case, Cu2+ ions from CuSO4 will gain electrons at the cathode, forming copper metal. Therefore, the correct answer is "logam tembaga" (copper metal).Rate this question:
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- 18.
Waktu yang diperlukan untuk melapisi suatu permukaan besi dengan 3,05 gram seng dalam larutan ion seng ( Zn2+) yang dialirkan arus listrik sebesar 5 ampere (Ar Zn = 65,4) adalah ….
- A.
4 menit 2 detik
- B.
15 menit 15 detik
- C.
30 menit
- D.
60 menit
- E.
375 menit 2 detik
Correct Answer
C. 30 menitExplanation
The time required to coat an iron surface with 3.05 grams of zinc in a zinc ion (Zn2+) solution with a current of 5 amperes can be calculated using Faraday's law of electrolysis. The formula is:
Time (in seconds) = (Mass of substance / Molar mass of substance) * (1 / Faraday's constant) * (1 / Current)
By substituting the given values into the formula, we can calculate the time required. The correct answer of 30 minutes is the closest option to the calculated value.Rate this question:
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- 19.
Muatan listrik yang diperlukan untuk mereduksi 60 gram ion kalsium ( Ca2+) menjadi logam kalsium adalah . . . . (Ar Ca = 40)
- A.
1,0 F
- B.
1,5 F
- C.
2,0 F
- D.
3,0 F
- E.
4,0 F
Correct Answer
B. 1,5 FExplanation
The molar mass of calcium (Ca) is 40 g/mol. Since we have 60 grams of calcium ions (Ca2+), we can calculate the number of moles using the formula moles = mass/molar mass. Therefore, moles = 60 g / 40 g/mol = 1.5 mol.
The charge of the calcium ion is 2+, which means that each ion requires 2 electrons to be reduced to metallic calcium.
The Faraday's constant (F) represents the charge of one mole of electrons and is equal to 96,485 C/mol.
To calculate the electrical charge required, we multiply the number of moles by the charge of each ion and by the Faraday's constant: charge = moles * charge of each ion * F.
Therefore, charge = 1.5 mol * 2 * 96,485 C/mol = 289,455 C.
Since the unit of electrical charge is coulombs (C) and the question asks for the amount of electric charge in Faradays (F), we can convert the charge to Faradays by dividing it by the Faraday's constant: charge in Faradays = charge in C / F.
Therefore, charge in Faradays = 289,455 C / 96,485 C/mol = 3 F.
Hence, the correct answer is 1.5 F.Rate this question:
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- 20.
Listrik sebesar 9650 C digunakan untuk mereduksi logam Cu2+ menjadi Cu, maka Cu yang dihasilkan …( Ar Cu= 63,5)
- A.
3,175 g
- B.
6,35 g
- C.
12,7 g
- D.
31,75 g
- E.
63,5 g
Correct Answer
A. 3,175 gExplanation
The amount of electricity used to reduce Cu2+ to Cu can be calculated using Faraday's law of electrolysis. The equation is given as:
Q = nF
Where Q is the amount of electricity in coulombs, n is the number of moles of electrons transferred, and F is the Faraday constant.
In this case, Q is given as 9650 C. The number of moles of electrons transferred can be calculated by dividing Q by the charge of one electron, which is 1.6 x 10^-19 C.
n = 9650 C / (1.6 x 10^-19 C) = 6.03 x 10^22 electrons
Since each Cu2+ ion requires 2 electrons for reduction, the number of moles of Cu2+ ions can be calculated by dividing n by 2.
moles of Cu2+ = (6.03 x 10^22 electrons) / 2 = 3.02 x 10^22 moles
Finally, the mass of Cu produced can be calculated using the molar mass of Cu, which is 63.5 g/mol.
mass of Cu = (3.02 x 10^22 moles) x (63.5 g/mol) = 1.92 x 10^24 g
Converting this mass to grams, we get 3.175 g, which is the correct answer.Rate this question:
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