1.
Hukum Kekalan Energi merupakan hukum dasar pada termokimia yg dikenal juga dengan……
Correct Answer
B. Hukum 1 Termodinamika
Explanation
The correct answer is "Hukum 1 Termodinamika" because the Law of Conservation of Energy, or Hukum Kekalan Energi, is one of the fundamental laws in thermodynamics. It states that energy cannot be created or destroyed, only transferred or transformed from one form to another. This law is also known as the First Law of Thermodynamics.
2.
Di dalam gelas kimia dilakukan pelarutan padatan NaOH menggunakan air. Pada reaksi tersebut ternyata terjadi kenaikan suhu. Berdasarkan hal tersebut, yang merupakan sistem adalah …
Correct Answer
D. Padatan NaOH dan air
Explanation
The correct answer is Padatan NaOH dan air. This is because the given scenario describes the dissolution of solid NaOH in water, which is an example of a chemical reaction. During this reaction, energy is released in the form of heat, causing an increase in temperature. The system in this case refers to the substances involved in the reaction, which are the solid NaOH and the water.
3.
Jika reaksi antara logam magnesium dan asam klorida encer tersebut dilakukan pada tabung reaksi yang tersumbat dengan rapat, gas hidrogen (materi) di dalam sistem tidak dapat terjadi pertukaran. Berdasarkan hal tersebut, tabung reaksi yang tersumbat termasuk ke dalam sistem …
Correct Answer
A. Tertutup
Explanation
The correct answer is "Tertutup" because in a closed system, no matter can enter or leave the system. In this case, since the gas hydrogen cannot escape or be exchanged with the surroundings, it indicates that the reaction is occurring in a closed system.
4.
Peristiwa yang mungkin terjadi pada sistem terisolasi……
Correct Answer
C. Tidak terjadi perpindahan kalor maupun zat antara lingkungan dan sistem
Explanation
The correct answer suggests that there is no transfer of heat or matter between the system and the surroundings. In other words, the system is completely isolated and does not interact with its environment in terms of heat or substance exchange.
5.
Pada pembentukan 1 mol air dari unsur-unsur pembentuknya dibebaskan kalor sebesar 285 kJ/mol. Persamaan termokimia untuk reaksi……
Correct Answer
C. H2(g)+ 1/2O2(g) → 2H2O(l) ∆Hf° = -285 kJ/mol
Explanation
The correct answer is H2(g)+ 1/2O2(g) → 2H2O(l) ∆Hf° = -285 kJ/mol. This is the correct answer because it represents the formation of 1 mol of water from its constituent elements, hydrogen gas (H2) and oxygen gas (O2). The coefficient of 1/2 in front of O2 indicates that only half a mole of O2 is required for the reaction. The negative sign in front of the enthalpy change (∆Hf°) indicates that the reaction is exothermic, meaning that heat is released during the formation of water. The value of -285 kJ/mol represents the amount of heat released per mole of water formed.
6.
Perhatikan reaksi berikut
1/2N2(g)+ 2H2(g)+ 1/2Cl2(g) → NH4Cl(s) ∆Hf°= -314,4 kJ/mol
Dibawah ini manakah pernyataan yang kurang tepat dari reaksi tersebut……
Correct Answer
D. Nilai perubahan entalpi berlaku untuk pembentukan 1 mol senyawa NH4Cl
Explanation
The given statement is incorrect because the enthalpy change (-314.4 kJ/mol) applies to the formation of 1/2 mol of NH4Cl, not 1 mol. The reaction equation shows that 1/2 mol of N2, 2 mol of H2, and 1/2 mol of Cl2 are required to form 1 mol of NH4Cl. Therefore, the enthalpy change should be multiplied by a factor of 2 to apply to the formation of 1 mol of NH4Cl.
7.
Perhatikan diagram berikut
Berikut ini pernyataan yang kurang tepat mengenai diagram energi diatas adalah…. (Ar H=1, O=16)
Correct Answer
E. Untuk menguapkan 36 gram air dilepaskan energi sebesar 43 kJ/mol
Explanation
The statement "Untuk menguapkan 36 gram air dilepaskan energi sebesar 43 kJ/mol" is incorrect because it states that 36 grams of water releases 43 kJ/mol of energy, which is not possible. The energy released during vaporization is dependent on the number of moles of water, not the mass. Therefore, the statement should be corrected to "Untuk menguapkan 1 mol air dilepaskan energi sebesar 43 kJ/mol."
8.
Dibawah ini yang merupakan contoh reaksi endoterm dalam kehidupan sehari-hari adalah….
Correct Answer
C. Fotosintesis
Explanation
Fotosintesis adalah contoh reaksi endoterm dalam kehidupan sehari-hari karena reaksi ini membutuhkan energi dalam bentuk cahaya matahari untuk dapat terjadi. Dalam proses fotosintesis, tumbuhan menggunakan energi cahaya matahari untuk mengubah air dan karbon dioksida menjadi glukosa dan oksigen. Reaksi ini memerlukan energi tambahan dari lingkungan sekitarnya, sehingga termasuk dalam reaksi endoterm.
9.
Manakah yang bukan merupakan ciri-ciri endoterm…….
Correct Answer
C. Suhu lingkungan bertambah
Explanation
The correct answer is "Suhu lingkungan bertambah." This is because an endothermic reaction is a reaction that absorbs heat from its surroundings, causing the temperature of the surroundings to decrease. In other words, the heat moves from the surroundings to the system, resulting in an increase in the system's energy and a decrease in the temperature of the surroundings. Therefore, the statement "Suhu lingkungan bertambah" contradicts the characteristics of an endothermic reaction.
10.
Perhatikan diagram energi berikut
Dari diagram berikut, manakah pernyataan yang benar……
Correct Answer
D. Energi pada sistem berkurang
Explanation
According to the given information, the statement "Energi pada sistem berkurang" is correct. This is because the diagram shows that the energy of the products is lower than the energy of the reactants, indicating a decrease in energy within the system.
11.
Perhatikan berbagai hasil percobaan berikut.
- Serbuk NH4Cl + serbuk Ca(OH)2, menghasilkan gas berbau tidak sedap disertai penurunan suhu
- Pita magnesium + larutan H2SO4, pita magnesium larut disertai kenaikan suhu
- Kapur CaO + air, dari hasil reaksi ini akan terasa panas di bila tangan menyentuh gelas kimia
- Gas N2O4 yang tidak berwarna berubah menjadi cokelat jika dipanaskan; jika pemanasan dihentikan perlahan-lahan kembali tidak berwarna
Proses yang tergolong reaksi eksoterm ditunjukkan oleh nomor …
Correct Answer
D. (2) dan (3)
Explanation
The correct answer is (2) and (3). In option (2), the reaction between magnesium and H2SO4 is exothermic because it releases heat, causing an increase in temperature. In option (3), the reaction between CaO and water is also exothermic because it releases heat, causing the glass container to feel hot when touched.
12.
Pernyataan yang benar tentang entalpi adalah …
Correct Answer
E. Perpindahan energi dari sistem ke lingkungan atau sebaliknya
Explanation
The correct answer is "Perpindahan energi dari sistem ke lingkungan atau sebaliknya." Entalpi is a thermodynamic property that represents the total energy of a system, including both its internal energy and the work done on or by the system. It is also a measure of the heat content of a substance or system. The statement "Perpindahan energi dari sistem ke lingkungan atau sebaliknya" refers to the transfer of energy between the system and its surroundings, which is a key aspect of enthalpy.
13.
Yang manakah pernyataan dibawah yang merupakan pengertian perubahan entalpi pembakaran standar……
Correct Answer
B. Kalor yang dilepaskan untuk membakar 1 mol zat
Explanation
The correct answer is "Kalor yang dilepaskan untuk membakar 1 mol zat". This answer accurately defines the standard enthalpy change of combustion, which refers to the heat released or generated when 1 mole of a substance undergoes complete combustion.
14.
Pernyataan yang benar untuk reaksi : H2(g)+ Cl2(g) →2 HCl(g) ∆H=x kJ adalah …
Correct Answer
E. Kalor pembentukan HCl = ½x kJ/mol
Explanation
The correct answer is "Kalor pembentukan HCl = ½x kJ/mol". This is because the reaction given is the formation of 2 moles of HCl from H2 and Cl2. The enthalpy change (∆H) for this reaction is x kJ. Therefore, the enthalpy change for the formation of 1 mole of HCl is ½x kJ/mol.
15.
Perhatikan beberapa persamaan berikut
- 2P(s)+ O2(g)+3Cl2(g)→ 2POCl3(g) ∆H= -1150 kJ
- H2(g)+ Cl2(g) →2HCl(g) ∆H= + 184 kJ
- 2P(s)+ 5Cl2(g)→2PCl5(g) ∆H= -640 kJ
- CH4(g)+ O2(g)→ 2CO2(g) + 2H2Og ∆H= - 802 kJ
Dari reaksi diatas manakah yang bukan merupakan reaksi pembakaran standar……
Correct Answer
C. 4
Explanation
The correct answer is 4 because the reaction 2P(s) + 5Cl2(g) → 2PCl5(g) involves the formation of a compound (PCl5) from its elements (P and Cl2), which is not a combustion reaction. Combustion reactions involve the reaction of a substance with oxygen to produce carbon dioxide and water.
16.
Suatu proses berlangsung dengan sistem melepas kalor sebesar 8 kJ ke lingkungan dan menerima kerja sebesar 100 J. Perubahan energi dalam sistem adalah …
Correct Answer
C. -7,9 kJ
Explanation
The process releases 8 kJ of heat to the surroundings and receives 100 J of work. To find the change in energy of the system, we need to consider the signs of heat and work. Since heat is released (negative) and work is received (positive), the change in energy is the sum of these two values, which is -7.9 kJ.
17.
Diketahui:
∆Hfo CO2 = -393 kJ/mol
∆Hfo H2O = -285 kJ/mol
∆Hfo C2H2 = +227 kJ/mol
Berapa kalor yang dibutuhkan untuk membakar 5,2 gram C2H2? (Ar C = 12 dan H = 1)
Correct Answer
C. -1298 kJ/mol
Explanation
The given question asks for the amount of heat required to burn 5.2 grams of C2H2. To calculate this, we need to determine the number of moles of C2H2 in 5.2 grams. The molar mass of C2H2 is 26 g/mol (2 * 12 g/mol for carbon + 2 * 1 g/mol for hydrogen). Therefore, the number of moles of C2H2 is 5.2 g / 26 g/mol = 0.2 mol. Since the enthalpy of formation (∆Hfo) of C2H2 is +227 kJ/mol, we can calculate the heat required using the formula: heat = ∆Hfo * moles = +227 kJ/mol * 0.2 mol = -1298 kJ/mol.
18.
Jika diketahui
∆H˚f CO2 = -393 kJ/mol
∆H˚f H2O = -242 kJ/mol
∆H˚f O2 = 0 kJ/mol
Berapakah nilai ∆H˚f CH4 jika diketahui persamaan termokimia untuk pembakaran metana adalah sebagai berikut
C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (g) ∆H = -1017 kJ/mol
Correct Answer
A. -1130 kJ/mol
Explanation
The given equation represents the combustion of methane (CH4). In the reaction, 1 mole of methane is burned to produce 1 mole of carbon dioxide (CO2) and 2 moles of water (H2O). The enthalpy change (∆H) for the reaction is given as -1017 kJ/mol. To find the enthalpy of formation (∆H˚f) of methane (CH4), we need to compare the given reaction with the standard enthalpies of formation of the products and reactants. By using the given standard enthalpies of formation for CO2 (-393 kJ/mol) and H2O (-242 kJ/mol), and considering the stoichiometry of the reaction, we can calculate the ∆H˚f of CH4 as -1130 kJ/mol.
19.
Sebanyak 6,2 gram NaOH ( Ar Na=14, O=16, H=1) dimasukkan ke dalam kalorimeter yang berisi 103,8 mL air. Setelah kristal NaOH larut, ternyata suhunya naik dari 24oC menjadi 32 oC. Kalor jenis larutannya 4,2 J/g.K dan kapasitas kalor kalorimetri adalah 12 J/K. Berapakah perubahan entalpi yang menyertai reaksi penetralan tersebut……
Correct Answer
D. -18,96 kJ/mol
Explanation
The given answer of -18,96 kJ/mol is the correct answer because it represents the change in enthalpy (ΔH) that accompanies the neutralization reaction. The question provides the mass of NaOH (6,2 grams) and the specific heat capacity of the solution (4,2 J/g.K). By using the formula q = mCΔT, where q is the heat absorbed or released, m is the mass, C is the specific heat capacity, and ΔT is the change in temperature, we can calculate the heat released by the reaction. Then, by dividing the heat released by the number of moles of NaOH (which can be calculated using the molar mass), we can find the change in enthalpy per mole of NaOH, which is -18,96 kJ/mol.
20.
Direaksikan 50 ml larutan HCl dengan konsentrasi 5 M direaksikan dengan 50 ml larutan KOH dengan konsentrasi 5 M di dalam suatu kalorimeter dan terjadi kenaikan suhu sebesar 7,5oC. Kalor jenis larutan dianggap 4,18 J/g.K dan massa jenis larutan dianggap 1gr/mL. Berapakah besar perubahan entalpi dari reaksi tersebut……
Correct Answer
A. -12.540 kJ/mol
Explanation
The negative sign in front of the enthalpy change indicates that the reaction is exothermic, meaning it releases heat to the surroundings. The magnitude of the enthalpy change can be calculated using the equation q = m x c x ΔT, where q is the heat released, m is the mass of the solution, c is the specific heat capacity of the solution, and ΔT is the change in temperature. Since the mass of the solution is 100 grams (50 ml x 1 gr/ml), the specific heat capacity is 4.18 J/g.K, and the change in temperature is 7.5oC, we can calculate the heat released. Converting the heat released to kilojoules and dividing by the number of moles of the limiting reactant gives us the enthalpy change in kJ/mol, which is -12.540 kJ/mol.
21.
Perhatikan diagram siklus berikut
Dari siklus diatas besar ∆Hfo SO2 adalah…..
Correct Answer
B. -298 kJ
Explanation
The correct answer is -298 kJ. This is because the diagram represents the formation of SO2, and the value of ∆Hfo (standard enthalpy of formation) for SO2 is -298 kJ/mol. This means that the formation of one mole of SO2 releases 298 kJ of energy.
22.
Siklus suatu reaksi ditunjukkan dengan diagram berikut
Berdasarkan siklus tersebut, nilai ∆H1 adalah …
Correct Answer
B. +105 kJ
Explanation
Based on the given diagram, the reaction proceeds in a clockwise direction. This means that the reactants have a lower energy level than the products. The value of ∆H1 represents the energy change for the reaction from reactants to the intermediate state. Since the reaction is endothermic (absorbs heat), the energy level increases. Therefore, the correct answer is +105 kJ, as it represents the increase in energy for the reaction.
23.
Diketahui energi ikatan rata-rata :
C - H = 414 kJ/mol C - O = 357 kJ/mol
C - C = 346 kJ/mol H - H = 436 kJ/mol
C = O = 740 kJ/mol O - H = 464 kJ/mol
Perubahan entalpi reaksi
Correct Answer
C. -59 kJ
Explanation
The given answer of -59 kJ is the correct answer because it represents the change in enthalpy of the reaction. The change in enthalpy is determined by subtracting the sum of the energy of the bonds broken from the sum of the energy of the bonds formed. In this case, the energy of the bonds broken is greater than the energy of the bonds formed, resulting in a negative value. Therefore, the reaction is exothermic, releasing 59 kJ of energy.
24.
Diketahui energi ikatan rata-rata :
H - H = 104,2 kkal/mol
Cl - Cl = 57,8 kkal/mol
H - Cl = 103,2 kkal/mol
Kalor yang diperlukan untuk menguraikan 109,5 gram HCl (Ar H = 1, Cl = 35,5 ) adalah …
Correct Answer
B. 66,6 kkal/mol
Explanation
The given question asks for the amount of heat required to decompose 109.5 grams of HCl. To solve this, we need to calculate the molar mass of HCl, which is the sum of the atomic masses of hydrogen (H) and chlorine (Cl). The molar mass of HCl is 1 + 35.5 = 36.5 grams/mol. Next, we use the given average bond energies to calculate the total energy required to break the bonds in 109.5 grams of HCl. The energy required is equal to the molar mass of HCl multiplied by the average bond energy of H-Cl, which is 103.2 kkal/mol. Therefore, the correct answer is 66.6 kkal/mol.
25.
Diketahui reaksi H2(g) + O2(g) → H2O2(l) ∆H = -188 kJ.
Jika energi ikatan H – H = 436 kJ/mol, O – H = 464 kJ/mol dan O = O = 500 kJ/mol, maka energi ikatan O – O adalah …
Correct Answer
A. 196 kJ/mol
Explanation
The energy change (∆H) for the reaction is -188 kJ, which means the reaction is exothermic. In the reaction, two H-H bonds are broken (2 x 436 kJ/mol) and two O-H bonds are formed (2 x 464 kJ/mol). Additionally, one O-O bond is formed. To find the energy of the O-O bond, we subtract the energy of the bonds broken from the energy of the bonds formed.
Total energy of bonds broken = 2 x 436 kJ/mol = 872 kJ/mol
Total energy of bonds formed = 2 x 464 kJ/mol + energy of O-O bond
Energy change (∆H) = energy of bonds formed - energy of bonds broken
-188 kJ = (2 x 464 kJ/mol) + energy of O-O bond - 872 kJ/mol
-188 kJ = 928 kJ/mol + energy of O-O bond - 872 kJ/mol
-188 kJ = 56 kJ/mol + energy of O-O bond
Therefore, the energy of the O-O bond is 56 kJ/mol.