Termokimia Practice Questions
UN (Indonesia) · UN Kimia · 152 free MCQs with instant results and detailed explanations.
152
Total
44
Easy
78
Medium
30
Hard
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Sample Questions from Termokimia
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Q1
Easy
What is the definition of enthalpy in thermodynamics?
A.
The internal energy plus the product of pressure and volume
B.
The energy required to raise the temperature of a substance
C.
The heat content of a compound at constant pressure
D.
The difference in energy between reactants and products
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Correct Answer: A
Enthalpy is defined as the internal energy of a system plus the product of its pressure and volume. This relationship helps in understanding heat transfer in processes occurring at constant pressure.
Q2
Easy
In an exothermic reaction, which of the following statements is true?
A.
Heat is absorbed from the surroundings.
B.
The enthalpy of the products is higher than that of the reactants.
C.
Heat is released to the surroundings.
D.
It occurs only at high temperatures.
Show Answer & Explanation
Correct Answer: C
In an exothermic reaction, heat is released to the surroundings as the reaction proceeds, resulting in a decrease in the enthalpy of the system.
Q3
Easy
What is the definition of enthalpy in thermochemistry?
A.
The total heat content of a system at constant pressure.
B.
The energy required to raise the temperature of a substance.
C.
The change in energy during a chemical reaction.
D.
The heat released during the reaction at constant volume.
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Correct Answer: A
Enthalpy is defined as the total heat content of a system at constant pressure, which includes both internal energy and the energy associated with pressure and volume.
Q4
Medium
What is the enthalpy change when 1 mole of water is formed from hydrogen and oxygen at standard conditions?
A.
-285.8 kJ
B.
-241.8 kJ
C.
-572.5 kJ
D.
0 kJ
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Correct Answer: A
The formation of water from hydrogen and oxygen is an exothermic reaction with a standard enthalpy change of -285.8 kJ/mol, indicating that energy is released.
Q5
Medium
Which of the following statements best describes an endothermic process?
A.
Heat is released to the surroundings.
B.
Heat is absorbed from the surroundings.
C.
Temperature decreases.
D.
It occurs spontaneously at room temperature.
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Correct Answer: B
An endothermic process is characterized by the absorption of heat from the surroundings, resulting in a decrease in the temperature of the surroundings.
Q6
Medium
Calculate the heat absorbed when 2 moles of a substance undergo a phase change with a heat of fusion of 6 kJ/mol.
A.
3 kJ
B.
6 kJ
C.
12 kJ
D.
18 kJ
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Correct Answer: C
The heat absorbed during a phase change is calculated by multiplying the number of moles by the heat of fusion. For 2 moles: 2 moles × 6 kJ/mol = 12 kJ.
Q7
Medium
Which process has the highest enthalpy change in a chemical reaction?
A.
Combustion of methane.
B.
Dissolving salt in water.
C.
Evaporation of water.
D.
Formation of ozone from oxygen.
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Correct Answer: A
Combustion of methane releases a significant amount of energy, making it one of the processes with the highest enthalpy change compared to the others listed.
Q8
Hard
A 50 g sample of water is heated from 25°C to 75°C. Calculate the amount of heat absorbed by the water. (Specific heat capacity of water = 4.18 J/g°C)
A.
1045 J
B.
2090 J
C.
1670 J
D.
1000 J
Show Answer & Explanation
Correct Answer: A
The heat absorbed can be calculated using the formula Q = mcΔT, where m is mass, c is specific heat capacity, and ΔT is the change in temperature. Here, Q = 50 g * 4.18 J/g°C * (75°C - 25°C) = 50 g * 4.18 J/g°C * 50°C = 1045 J.
Q9
Hard
What is the enthalpy change when 2 moles of propane (C3H8) combust completely in excess oxygen? The enthalpy of formation for C3H8 is -104.7 kJ/mol and for CO2 is -393.5 kJ/mol, and for H2O is -285.8 kJ/mol.
A.
-2219.2 kJ
B.
-5000 kJ
C.
-4000 kJ
D.
-1400 kJ
Show Answer & Explanation
Correct Answer: A
The combustion of propane can be represented by the equation: C3H8 + 5O2 → 3CO2 + 4H2O. Calculating the enthalpy change, ΔH = [3(-393.5) + 4(-285.8)] - [2(-104.7)]. This results in ΔH = -2219.2 kJ for the complete combustion of 2 moles of propane.
Q10
Hard
A calorimeter absorbs 500 J of heat from a chemical reaction, causing a temperature increase of 2°C. What is the heat capacity of the calorimeter?
A.
250 J/°C
B.
200 J/°C
C.
150 J/°C
D.
100 J/°C
Show Answer & Explanation
Correct Answer: A
Heat capacity (C) can be calculated using the formula C = Q/ΔT, where Q is the heat absorbed and ΔT is the temperature change. Thus, C = 500 J / 2°C = 250 J/°C. Hence, A is correct.
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Termokimia — UN (Indonesia) UN Kimia Practice Questions Online
This page contains 152 practice MCQs for the chapter Termokimia in UN (Indonesia) UN Kimia. The questions are organized by difficulty — 44 easy, 78 medium, 30 hard — so you can choose the right level for your preparation.
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