General Chemistry

Question 1

What does the first law of thermodynamics state?

• A) Energy can be created and destroyed.
• B) Energy can only be transformed from one form to another.
• C) Energy is always lost in a closed system.
• D) Energy can be created from nothing.

Answer 1

B) Energy can only be transformed from one form to another.

Question 2

In the equation ΔQ=ΔU+W, what does ΔQ represent?
* A) Work done by the system.
* B) Change in internal energy.
* C) Heat added to the system.
* D) Total energy of the system.

Answer 2

C) Heat added to the system.

Question 3

Which of the following best describes internal energy (ΔU?)
* A) The energy lost during work.
* B) The total kinetic and potential energy of particles in a system.
* C) The heat transferred out of a system.
* D) The work done on the surroundings.

Answer 3

B) The total kinetic and potential energy of particles in a system.

Question 4

What happens to energy in an isolated system according to the first law of thermodynamics?
* A) It decreases over time.
* B) It remains constant.
* C) It can increase indefinitely.
* D) It can be created from heat.

Answer 4

B) It remains constant.

Question 5

If a system does 50 J of work and receives 100 J of heat, what is the change in internal energy?
* A) 150 J
* B) 50 J
* C) 100 J
* D) 0 J

Answer 5

B) 50 J

Question 6

In an isolated system, if 200 J of work is done on the system and no heat is exchanged with the surroundings, what happens to the internal energy of the system?
* A) It decreases by 200 J.
* B) It increases by 200 J.
* C) It remains constant.
* D) It increases by 400 J.

Answer 6

C) It remains constant.

Question 7

What does the enthalpy of a reaction measure?
* A) The total energy of reactants.
* B) The heat content change during a chemical reaction at
constant pressure.
* C) The volume change of the system.
* D) The temperature change during a reaction.

Answer 7

B) The heat content change during a chemical reaction at
constant pressure.

Question 8

In an exothermic reaction, what is the sign of ΔHreaction?
* A) Positive
* B) Negative
* C) Zero
* D) Undefined

Answer 8

B) Negative

Question 9

Which law states that the total enthalpy change for a reaction is the same regardless of the path
taken?
* A) First Law of Thermodynamics
* B) Hess’s Law
* C) Second Law of Thermodynamics
* D) Law of Conservation of Mass

Answer 9

B) Hess’s Law

Question 10

What is the standard condition for
measuring standard enthalpy of reaction?
* A) 1 atm pressure and 298 K temperature
* B) 1 bar pressure and 373 K temperature
* C) 1 bar pressure and 298 K temperature
* D) 1 atm pressure and 273 K temperature

Answer 10

C) 1 bar pressure and 298 K temperature

Question 11

If the enthalpy change for a reaction is +150 kJ, what type of reaction is it?
* A) Exothermic
* B) Endothermic
* C) Isothermal
* D) Spontaneous

Answer 11

B) Endothermic

Question 12

How can enthalpy changes be experimentally determined?
* A) By measuring temperature changes only.
* B) Using calorimetry to measure heat exchange.
* C) By calculating bond energies only.
* D) By observing color changes in reactions.

Answer 12

B) Using calorimetry to measure heat exchange.

Question 13

What does Hess’s Law state about
enthalpy changes?
* A) Enthalpy changes depend on the path taken.
* B) The total enthalpy change for a reaction is independent of the
steps taken.
* C) Enthalpy changes can only be calculated for one-step
reactions.
* D) Enthalpy cannot be measured experimentally

Answer 13

B) The total enthalpy change for a reaction is independent of the
steps taken.

Question 14

If you know the enthalpy changes for two reactions, how
can you find the enthalpy change for a third reaction that is
the sum of those two?
* A) By averaging the two enthalpy changes.
* B) By adding the two enthalpy changes together.
* C) By multiplying one of them by two.
* D) By subtracting one from the other.

Answer 14

B) By adding the two enthalpy changes together.

Question 15

Which of the following is true regarding Hess’s Law?
* A) It applies only to exothermic reactions.
* B) It applies only to endothermic reactions.
* C) It can be applied to any chemical reaction regardless of
whether it is exothermic or endothermic.
* D) It only applies to gaseous reactions

Answer 15

C) It can be applied to any chemical reaction regardless of
whether it is exothermic or endothermic.

Question 16

In a reaction where 100 kJ of energy is released in one step and 50 kJ in another, what is the total enthalpy change according to Hess’s Law?
* A) 150 kJ
* B) 50 kJ
* C) 100 kJ
* D) −150 kJ

Answer 16

D) −150 kJ

Question 17

If a reaction can be expressed as two steps with known enthalpy changes of −200 kJ and +50 kJ, what is the overall enthalpy change for the reaction?
* A) −250 kJ
* B) −150 kJ
* C) +150 kJ
* D) +250 kJ

Answer 17

B) −150 kJ

Question 18

What type of thermodynamic process does Hess’s Law apply to?
* A) Only reversible processes
* B) Only irreversible processes
* C) Any process that can be expressed as a series of steps
* D) Only gas-phase reactions

Answer 18

C) Any process that can be expressed as a series of steps

Question 19

Which factor typically increases the rate of a chemical reaction?
* A) Decreasing temperature
* B) Increasing concentration
* C) Decreasing surface area
* D) Adding inhibitors

Answer 19

B) Increasing concentration

Question 20

How does temperature affect the rate of a reaction?
* A) It has no effect.
* B) Higher temperatures decrease particle movement.
* C) Higher temperatures increase particle movement and collision
frequency.
* D) Lower temperatures increase particle collisions.

Answer 20

C) Higher temperatures increase particle movement and collision
frequency.

Question 21

What is the effect of increasing the surface area of solid reactants on reaction rates?
* A) It decreases the reaction rate.
* B) It has no effect on the reaction rate.
* C) It increases the reaction rate.
* D) It only affects gaseous reactions.

Answer 21

C) It increases the reaction rate.

Question 22

What role do catalysts play in chemical reactions?
* A) They slow down reactions.
* B) They change the products formed.
* C) They increase the activation energy required for reactions.
* D) They speed up reactions by lowering activation energy.

Answer 22

D) They speed up reactions by lowering activation energy.

Question 23

Which statement is true regarding
inhibitors?
* A) They increase the rate of reactions.
* B) They have no effect on reaction rates.
* C) They decrease the rate of reactions.
* D) They are always catalysts.

Answer 23

C) They decrease the rate of reactions.

Question 24

What is one way that the nature of
reactants influences reaction rates?
* A) All reactants have identical rates regardless of their properties.
* B) Some reactants require more energy to break bonds than
others, affecting their reactivity.
* C) Only gaseous reactants can participate in fast reactions.
* D) Solid reactants always react faster than liquids.

Answer 24

B) Some reactants require more energy to break bonds than
others, affecting their reactivity.

Question 25

Which of the following factors would most likely decrease the rate of a chemical reaction? * A) Increasing the concentration of reactants * B) Decreasing the temperature of the reaction * C) Increasing the surface area of solid reactants * D) Adding a catalyst to the reaction

Answer 25

B) Decreasing the temperature of the reaction

Question 26

When the concentration of a reactant increases, what happens to the reaction rate? A. Increases B. Decreases C. Remains constant D. Shows no correlation.

Answer 26

A. Increases

Question 27

What form of reactant would likely result in a faster reaction rate? A. Finely powdered B. Large chunks C. No discernible effect D. Both show similar rates

Answer 27

A. Finely powdered

Question 28

3. What effect does an increase in surface area of a solid reactant have on the reaction rate? A. Decreases B. Remains constant C. Increases D. No discernible impact

Answer 28

C. Increases

Question 29

4. In a chemical reaction, if the temperature is lowered, what generally happens to the reaction rate? A. Increases B. Remains constant C. Decreases D. Fluctuates

Answer 29

C. Decreases

Question 30

5. rate = k[NO2] 2 A. First order B. Second order C. Third order D. Fourth order

Answer 30

B. Second order

Question 31

6. rate = k A. First order B. Second order C. Third order D. Zero order

Answer 31

D. Zero order

Question 32

7. rate = k[H2][Br2]1 /2 A. First order B. Second order C. 1.5 order D. Fourth order

Answer 32

C. 1.5 order

Question 33

8. rate = k[NO]2 [O2] A. First order B. Second order C. Third order D. Fourth order

Answer 33

C. Third order

Question 34

9. Consider the following factors. Which combination of the above factors is required for effective collisions? I. Reactant particles collide. II. Sufficient kinetic energy is present. III. A favorable geometry exists. A. I & II B. II & III C. I & III D. I, II, & III

Answer 34

D. I, II, & III

Question 35

10. Which statement among the following regarding chemical reactions and molecular collisions is inaccurate? A. Any chemical reaction results in the breaking of some bonds (which requires energy) and the formation of new ones (which releases energy). B. Particles that lack the necessary kinetic energy may collide and will not result in a chemical reaction. C. If a collision is relatively gentle, there is sufficient energy available to initiate the bond-breaking process, and thus the particles do not react. D. Activation energy is involved in breaking some of the original bonds.

Answer 35

C. If a collision is relatively gentle, there is sufficient energy available to initiate the bond-breaking process, and thus the particles do not react.

Question 36

11. The _____________ refers to a chemical entity characterized by bonds that are partially broken and partially formed, resulting in high energy. A. Energy profile B. Activation energy C. Activated complex D. Reaction mechanism

Answer 36

C. Activated complex

Question 37

12. When a lit match is touched to the wick of a candle, the candle begins to burn. When the match is removed, the candle continues to burn, the match. A. Behaves as a catalyst B. Supplies the activation energy C. Is part of the rate determining step D. Lowers the activation energy barrier

Answer 37

B. Supplies the activation energy

Question 38

13. The minimum quantity of energy required to initiate a reaction is known as the A. Activation energy. B. Energy of reaction. C. Entropy of reaction D. Reaction mechanism energy

Answer 38

A. Activation energy.

Question 39

14. The rate of a reaction depends on __________. A. Collision frequency B. Collision orientation C. Collision energy D. All of the above

Answer 39

D. All of the above

Question 40

15. It is the catalyst, such as enzymes or hormones, that initiates or increases the rate of chemical reaction. A. Biocatalyst B. Positive catalyst C. Negative catalyst D. Induced catalyst

Answer 40

A. Biocatalyst

Question 41

16. What type of catalyst decreases the activation energy by accepting an alternative path for the reaction to occur? A. Biocatalyst B. Positive catalyst C. Negative catalyst D. Induced catalyst

Answer 41

B. Positive catalyst

Question 42

17. Which among the choices is the catalyst that influences the speed of a reaction which is not possible under ordinary conditions? A. Biocatalyst B. Positive catalyst C. Negative catalyst D. Induced catalyst

Answer 42

D. Induced catalyst

Question 43

18. Which of the following processes does not occur spontaneously? A. Sugar dissolving in hot coffee. B. Coffee freezing while you drink it on a warm summer day. C. A nail rusting over the course of years. D. Ripening of fruits

Answer 43

B. Coffee freezing while you drink it on a warm summer day.

Question 44

19. Which of the following statements accurately describes the concept of spontaneity in a process? A. A spontaneous process can be reversed by changing the temperature. B. A spontaneous process always occurs at equilibrium. C. A spontaneous process always leads to an increase in disorder. D. A spontaneous process is always exothermic.

Answer 44

C. A spontaneous process always leads to an increase in disorder.

Question 45

20. Which of the following processes is non-spontaneous? A. cooling of a hot flat iron B. drop of ink dispersing in water C. black hair turning grey. D. straightening curly hair

Answer 45

D. straightening curly hair

Question 46

21. Which law of thermodynamics asserts that the overall entropy of the universe always increases? A. First law of thermodynamics B. Second law of thermodynamics C. Third law of thermodynamics D. None of these

Answer 46

B. Second law of thermodynamics

Question 47

22. Standard entropy is measure at ____________________________. A. 25oC and 1.0 atm B. 25oC and 2.0 atm C. 100oC and 1.0 atm D. 25oC and 2.5 atm

Answer 47

A. 25oC and 1.0 atm

Question 48

23. How is entropy quantified or measured in statistical terms? A. Disorder of a system B. Heat of a system C. Order of a system D. Cooling of a system

Answer 48

A. Disorder of a system

Question 49

24. The standard free-energy change for a reaction, ΔG°, can be calculated from the standard free energies of formation of reactants and products. A. True B. False C. Sometimes true D. Sometimes false

Answer 49

A. True

Question 50

25. Under conditions of constant temperature and pressure, the free-energy change, ΔG is less than zero for a spontaneous process and greater than zero for a nonspontaneous process. A. True B. False C. Sometimes true D. Sometimes false

Answer 50

A. True

Question 51

26. What does it signify when the standard free energy change (ΔG°) is zero? A. The reaction is spontaneous at standard condition. B. The reaction is nonspontaneous at standard condition. C. The system is at equilibrium at standard condition. D. The reaction is both nonspontaneous and at equilibrium

Answer 51

C. The system is at equilibrium at standard condition.