1.
Senyawa seng dari unsur transisi tidak berwarna, hal ini disebabkan oleh....
Correct Answer
A. Orbital d telah penuh terisi elektron
Explanation
The correct answer is "Orbital d telah penuh terisi elektron." This is because transition metal compounds are often colorless due to the presence of completely filled d orbitals. When d orbitals are fully occupied, they do not absorb visible light, resulting in the compound appearing colorless.
2.
Diboran, B2H6 disintesis dengan reaksi:
3 NaBH4 + 4 BF3 3 NaBF4 + 2 B2H6.
Bila reaksi ini memiliki 70 % yield, berapa mol NaBH4 harus direaksikan dengan BF3 berlebih agar didapatkan 0,400 mol B2H6:
Correct Answer
D. 0,858
Explanation
The question asks for the amount of NaBH4 that needs to be reacted with excess BF3 in order to obtain 0.400 mol of B2H6. Since the reaction has a 70% yield, it means that only 70% of the theoretical amount of B2H6 will be obtained. Therefore, the amount of B2H6 that would be obtained with 100% yield is 0.400 mol / 0.70 = 0.571 mol. According to the balanced equation, 2 mol of B2H6 is produced from 3 mol of NaBH4. So, the amount of NaBH4 needed to produce 0.571 mol of B2H6 is (0.571 mol / 2 mol) * 3 mol = 0.857 mol, which is approximately 0.858 mol.
3.
Sejumlah 2,839-g sampel C2H4O (44 g/mol) dibakar dalam kalorimeter bom yang kapasitas panasnya 16,77 kJ/°C. Temperatur kalorimeter meningkat dari 22,62°C menjadi 26,87°C. Berapa entalpi pembakaran per mol C2H4O?
Correct Answer
C. -1,10 x103 kJ/mol
Explanation
The enthalpy change of combustion per mole of C2H4O can be calculated using the formula:
ΔH = q / n
Where:
ΔH = enthalpy change
q = heat released or absorbed during the reaction
n = number of moles of C2H4O
In this case, the heat released (q) can be calculated using the formula:
q = CΔT
Where:
C = heat capacity of the calorimeter
ΔT = change in temperature
Substituting the given values:
C = 16.77 kJ/°C
ΔT = 26.87°C - 22.62°C = 4.25°C
q = 16.77 kJ/°C * 4.25°C = 71.3025 kJ
Now, we need to calculate the number of moles of C2H4O in the sample:
n = mass / molar mass
n = 2.839 g / 44 g/mol = 0.0645 mol
Finally, substituting the values in the first formula:
ΔH = 71.3025 kJ / 0.0645 mol = -1,105.04 kJ/mol
Rounded to two decimal places, the enthalpy change of combustion per mole of C2H4O is -1.10 x 10^3 kJ/mol, which matches the given answer.
4.
Asam karbonat, H2CO3, adalah asam berproton ganda. Bila tetapan kesetimbangan disosiasi pertama Ka1= 4,3 x 10-7 dan disosiasi kedua Ka2 = 5,6 x 10-11, maka [H+] larutan 0,100 M H2CO3 adalah, (hanya disosiasi pertama yang dominan)
Correct Answer
B. 2,07 x 104 M
5.
Asam tartarat, H2C4H4O6, merupakan asam berproton dua. Asam ini terkandung dalam minuman anggur, dan akan mengendap seiring dengan makin lamanya minuman anggur tersebut. Sebanyak 40 mL larutan asam tartarat dalam minuman anggur, dititrasi dengan larutan NaOH 2,000 M, dan untuk mentitrasi kedua proton yang bersifat asam tersebut dibutuhkan 22,62 mL larutan NaOH. Tentukanlah molaritas larutan asam tartarat tersebut.
Correct Answer
C. 0.5655 M
Explanation
The molaritas larutan asam tartarat dapat ditentukan dengan menggunakan persamaan stoikiometri antara asam tartarat dan NaOH. Diketahui bahwa 22,62 mL larutan NaOH 2,000 M dibutuhkan untuk mentitrasi kedua proton yang bersifat asam tersebut. Oleh karena itu, jumlah mol NaOH yang digunakan adalah 2 x 22,62 mL x 0,00200 M = 0,09048 mol. Karena asam tartarat merupakan asam berproton dua, maka jumlah mol asam tartarat yang bereaksi adalah 0,09048 mol. Molaritas larutan asam tartarat dapat dihitung dengan membagi jumlah mol asam tartarat dengan volume larutan yang digunakan, yaitu 0,09048 mol / 0,0400 L = 0,5655 M.
6.
Sebanyak n gram NaOH (Mr = 40) memiliki pH 12. Jika dilarutkan dalam air sampai volumenya 500 mL, harga n adalah
Correct Answer
E. 0,2 gram
Explanation
Based on the given information, we know that the n gram of NaOH has a pH of 12 when dissolved in water. This means that the solution is highly basic. The pH scale ranges from 0 to 14, where a pH of 7 is considered neutral, below 7 is acidic, and above 7 is basic. Since NaOH is a strong base, it completely dissociates in water to produce hydroxide ions (OH-) which increase the concentration of hydroxide ions in the solution, resulting in a high pH. Therefore, to achieve a pH of 12, only a small amount of NaOH is needed, which is 0.2 grams.
7.
Hasil kali kelarutan (Ksp) dari Mg(OH)2 = 1,2 × 10-11. Bila ke dalam larutan ditambahkan NaOH padat agar terjadi kenaikan pH pada MgCl2 0,2 M, maka endapan akan mulai terbentuk pada pH kira-kira
Correct Answer
B. 9
Explanation
The correct answer is 9. When NaOH is added to the solution of MgCl2, it will react with Mg2+ ions to form Mg(OH)2. The solubility product constant (Ksp) of Mg(OH)2 is given as 1.2 x 10-11, which means that it has a very low solubility. As the pH increases, the concentration of hydroxide ions (OH-) in the solution also increases. When the pH reaches a certain point, the concentration of OH- ions will exceed the solubility product constant and precipitation of Mg(OH)2 will occur. Since the Ksp of Mg(OH)2 is very low, the precipitation will start at a pH of approximately 9.
8.
Manakah di antara pernyataan berikut yang benar tentang silicon?
1. Jari-jari silikon lebih besar dari karbon
2. Dapat membentuk ikatan π sesamanya
3. Dapat membentuk ikatan tunggal σ
4. Unsur yang sangat reaktif
Correct Answer
B. B
Explanation
Silicon dapat membentuk ikatan π sesamanya.
9.
Di antara senyawa berikut yang merupakan isomer dari C6H14 adalah
1. n-heksana
2. Neoheksana
3. Isoheksana
4. 2,3 dimetil butana
Correct Answer
E. E
10.
Dari unsur-unsur logam transisi dalam berikut yang termasuk golongan aktinida yaitu
1. Mendelevium (Md)
2. Thorium (Th)
3. Nobelium (No)
4. Lutesium (Lu)
Correct Answer
C. C
Explanation
The correct answer is C. The actinide series is a group of elements in the periodic table that are all radioactive and have similar properties. Mendelevium (Md), Nobelium (No), and Lutetium (Lu) are all elements that belong to the actinide series. Thorium (Th) is not an actinide element, it belongs to the actinide series. Therefore, the correct answer is C.
11.
Logam natrium lebih mudah dioksidasi dibandingkan dengan logam magnesium
SEBAB
Kekuatan logam natrium dalam mereduksi air lebih besar dibandingkan dengan logam magnesium
Correct Answer
A. A
Explanation
The correct answer is A. Sodium is more easily oxidized compared to magnesium because sodium has a greater reducing power in water.
12.
Proses Penggumpalan putih telur akibat pemanasan terjadi karena proses denaturasi protein
SEBAB
Denaturasi protein adalah hilangnya sifat-sifat alamiah protein karena rusaknya struktur-struktur protein selain struktur utama (primer)
Correct Answer
A. A
Explanation
The correct answer is A. The explanation for this is that the process of coagulation of egg whites due to heating occurs because of the denaturation of proteins. Denaturation is the loss of natural properties of proteins due to the damage of protein structures other than the main structure (primary structure).
13.
Contoh asam amino yang hanya terdapat dalam protein tetapi adalah hidroksiprolin dan sistein
SEBAB
Hidroksiprolin adalah turunan prolin yang terdapat dalam kolagen, sedangkan sistein adalah hasil kondensasi dari dua sistein
Correct Answer
B. B
Explanation
Hidroksiprolin dan sistein adalah dua asam amino yang hanya ditemukan dalam protein. Hidroksiprolin adalah turunan dari asam amino prolin yang terdapat dalam kolagen, sedangkan sistein terbentuk melalui kondensasi dari dua molekul sistein. Oleh karena itu, kedua asam amino ini hanya ditemukan dalam protein dan tidak ditemukan dalam bentuk bebas di alam.
14.
Ion berikut ini, manakah yang mempunyai elektron lebih banyak daripada proton dan lebih banyak proton daripada neutron? [H = 11H; D = 21H; He 42He; O 168O]
Correct Answer
A. D-
Explanation
D- is the correct answer because it has one more electron than proton and one more proton than neutron. The symbol "D-" represents a deuterium ion, which is a hydrogen isotope with one proton, one neutron, and one electron.
15.
Which one do you like?
Correct Answer
A. Option 1
16.
Energi ionisasi berturutan (dalam kJ.mol-1) dari unsur X berikut ini adalah :
870 ; 1800 ; 3000 ; 3600 ; 5800 ; 7000 ; 13200
Apakah unsur X ini:
Correct Answer
D. 52Te
Explanation
The answer is 52Te because it has the highest ionization energy among the given elements. The ionization energy increases as you move across a period in the periodic table, and Te is the element with the highest ionization energy in its period.
17.
Pernyataan yang bukanmengenai Uranium yaitu
Correct Answer
A. Mempunyai nomor atom 92
Explanation
Uranium memiliki nomor atom 92, jadi pernyataan ini adalah benar. Pernyataan lainnya tidak benar mengenai Uranium.
18.
Berturut- turut, bagaimana masing masing hibridisasi dari atom nomor 1 hingga nomor 4 berikut ini...
Correct Answer
B. Sp2 sp2 sp3 sp
Explanation
The correct answer is "sp2 sp2 sp3 sp". This is because the question is asking for the hybridization of atoms numbered 1 to 4. The hybridization of an atom is determined by the number of sigma bonds and lone pairs around it. In the given answer, atom number 1 is sp2 hybridized because it has 1 sigma bond and 1 lone pair, atom number 2 is sp2 hybridized because it has 2 sigma bonds and no lone pairs, atom number 3 is sp3 hybridized because it has 3 sigma bonds and no lone pairs, and atom number 4 is sp hybridized because it has 1 sigma bond and no lone pairs.
19.
Geometri molekul dari CH2O adalah
Correct Answer
B. Trigonal planar
Explanation
The correct answer is trigonal planar because the molecular geometry of CH2O, which is formaldehyde, is trigonal planar. In a trigonal planar geometry, the central carbon atom is bonded to three other atoms, in this case, two hydrogen atoms and one oxygen atom. The bond angles between these atoms are approximately 120 degrees, resulting in a flat, triangular shape. Therefore, the correct answer is trigonal planar.
20.
Bila 1,50 g padatan H2C2O4.2H2O dan membebaskan seluruh molekul air yang terhidrasi maka akan diperoleh H2C2O4 sebanyak :
Correct Answer
C. 1,07 g
Explanation
The question states that 1.50 g of hydrated oxalic acid (H2C2O4.2H2O) is completely dehydrated, meaning all the water molecules are removed. The molar mass of H2C2O4.2H2O is 126 g/mol. To find the mass of H2C2O4, we need to subtract the mass of water (2H2O) from the total mass. The molar mass of water is 18 g/mol, so the mass of water in H2C2O4.2H2O is 36 g. Subtracting this from the total mass gives us 1.50 g - 36 g = 1.14 g. Therefore, the correct answer is 1.07 g.
21.
Manakah senyawa berikut yang tidak bereaksi dengan propil-magnesium bromida?
Correct Answer
D. D
Explanation
Senyawa yang tidak bereaksi dengan propil-magnesium bromida adalah D.
22.
Dari reaksi-reaksi di bawah, manakah yang tidak langsung menghasilkan asam karboksilat ?
Correct Answer
B. B
Explanation
Reaksi yang tidak langsung menghasilkan asam karboksilat adalah reaksi B.
23.
Urea bereaksi dengan asam nitrit sebagai berikut :
NH2CONH2(s) + 2 HNO2(aq) --> CO2(g) + 2 N2(g) + 3 H2O(aq)
Bila 0,24 gram urea direaksikan dengan HNO2 berlebihan, hitunglah volume gas yang dihasilkan dalam reaksi tersebut! (diketahui volume 1 mol gas, kondisi STP = 24 dm3 )
Correct Answer
A. 96 cm3
Explanation
The balanced equation shows that for every 1 mole of urea reacted, 2 moles of N2 gas are produced. Since the molar mass of urea is 60 g/mol, the number of moles of urea can be calculated by dividing the mass (0.24 g) by the molar mass (60 g/mol), which gives 0.004 moles of urea. Therefore, the number of moles of N2 gas produced is twice that, which is 0.008 moles. Using the volume of 1 mole of gas at STP (24 dm3), the volume of N2 gas produced can be calculated by multiplying the number of moles (0.008 moles) by the molar volume (24 dm3/mol), which gives 0.192 dm3 or 192 cm3. Therefore, the correct answer is 192 cm3.
24.
Dalam senyawa yang manakah atom halogen bereaksi paling cepat dengan larutan NaOH ?
Correct Answer
E. Sama cepat
Explanation
The correct answer is "sama cepat" which means "equally fast" in English. This suggests that both compounds, CH3CH2CH2Cl and CH3CH2CH2F, react at the same rate with NaOH solution. This implies that the halogen atoms in both compounds have similar reactivity towards NaOH.
25.
Ikatan rangkap tiga dalam etuna terdiri dari :
Correct Answer
C.
Explanation
Ikatan rangkap tiga dalam etuna terdiri dari tiga pasangan elektron yang terbagi dalam tiga orbital hibrida. Ketiga pasangan elektron ini terletak pada tiga orbital yang berbeda, dan membentuk ikatan yang kuat antara atom-atom yang terlibat. Ikatan rangkap tiga biasanya terbentuk antara atom karbon dalam senyawa organik, seperti senyawa alkuna. Dalam ikatan rangkap tiga, ada satu ikatan sigma dan dua ikatan pi yang terbentuk antara atom-atom yang terikat. Ikatan rangkap tiga memiliki kekuatan yang lebih besar daripada ikatan rangkap dua atau ikatan tunggal, karena terdapat lebih banyak pasangan elektron yang terlibat.
26.
Pasangan pernyataan berikut ini, manakah yang setara (sepadan) /cocok?
Correct Answer
C. Tekanan uap rendah- titik didih tinggi
Explanation
The statement "Tekanan uap rendah - titik didih tinggi" is the correct answer because it states that when the vapor pressure is low, the boiling point is high. This is consistent with the relationship between vapor pressure and boiling point, as lower vapor pressure indicates a stronger intermolecular force, which requires more energy to break and reach the boiling point.
27.
Berikut ini pernyataan mengenai etanol, CH3CH2OH
I. Etanol mengandung ikatan O-H polar sehingga dapat bercampur baik dengan air.
II. Etanol membentuk ikatan hidrogen dengan air.
III.Titik didih didih etanol lebih tinggi dibandingkan hidrokarbon dengan jumlah atom karbon yang sama.
IV. Pada temperatur sama, tekanan uap jenuh etanol lebih rendah dari air
Manakah pernyataan yang BENAR :
Correct Answer
C. Pernyataan I, II, dan III
Explanation
The correct answer is "Pernyataan I, II, dan III".
Pernyataan I is correct because ethanol contains a polar O-H bond, allowing it to mix well with water.
Pernyataan II is correct because ethanol can form hydrogen bonds with water.
Pernyataan III is correct because ethanol has a higher boiling point than hydrocarbons with the same number of carbon atoms.
Therefore, all three statements are true.
28.
Reaksi berikut ini berlangsung dalam air:
Berikut ini manakah pernyataan yang tidak benar:
Correct Answer
E. Merupakan reaksi auto-redoks
Explanation
The given answer states that the reaction is an auto-redox reaction. An auto-redox reaction is a reaction in which the same substance is both oxidized and reduced. However, based on the information provided in the question, there is no indication that the same substance is being both oxidized and reduced. Therefore, the statement that the reaction is an auto-redox reaction is incorrect.
29.
Dari diagram energi reaksi berikut ini (energi bebas Gibbs), manakah yang nilai tetapan kesetimbangannya sama dengan SATU ?
Correct Answer
B. Hanya II
Explanation
The correct answer is "hanya II". This means that only II has an equilibrium constant value of one. The equilibrium constant is a measure of the extent to which a reaction proceeds towards the products. A value of one indicates that the reaction is in equilibrium, with equal amounts of reactants and products.
30.
Proses peluruhan radioaktif umumnya mengikuti kinetika reaksi orde-1. Suatu isotop memiliki waktu paruh 10 menit. Jumlah isotop radioaktif yang tersisa setelah 40 menit adalah
Correct Answer
C. 1/16 kali semula
Explanation
The decay of radioactive isotopes generally follows first-order reaction kinetics. The half-life of an isotope is the time it takes for half of the initial amount of the isotope to decay. In this case, the half-life is 10 minutes. After 40 minutes, which is 4 half-lives, the remaining amount of the radioactive isotope can be calculated by multiplying the initial amount by (1/2)^4, which is equal to 1/16. Therefore, the correct answer is 1/16 times the initial amount.