7. According to collision theory, what needs to happen for a reaction to take place?
A. particles need to be in the same phase
B. particles must collide in the correct orientation
C. particles must collide in any orientation
D. a transfer of energy from the system to the surroundings must take place
B. particles must collide in the correct orientation
8. Enzymes are found in the human body as a _____ for organic reactions that would otherwise be too slow.
A. collider
B. key
C. catalyst
D. temperature boost
C. catalyst
H2 + O2, what purpose does the flame (lighter) serve?
A. The flame causes condensation
B. The flame provides activation energy.
C. The flame is one of the reactants.
D. The flame provides energy for electrolysis.
B. The flame provides activation energy.
10. Calorimeters are used to measure bond energy by providing
A. an open system, where matter and heat can be exchanged with the surroundings.
B. A closed system, where heat can be exchanged with the surroundings, but not matter.
C. An isolated system, where neither heat nor matter can be exchanged with the surroundings.
D. A combined system, where heat and matter can periodically be exchanged with the surroundings.
C. An isolated system, where neither heat nor matter can be exchanged with the surroundings.
12. The speed at which a reaction takes place is the
A. reaction rate
B. reactant concentration
C. kinetic energy
D. reaction orientation
A. reaction rate
To determine the correct answer, we need to understand the concept of collision theory. Collision theory states that for a reaction to occur, particles must collide with each other. Based on this understanding, we can now evaluate the answer choices.
A. Particles need to be in the same phase: This is not a requirement for a reaction to take place. Reacting particles can be in different phases, such as solids, liquids, or gases.
B. Particles must collide in the correct orientation: This is a correct requirement for a reaction to occur. In order for the reactant molecules to effectively interact and form new bonds, they must collide with each other in the appropriate orientation.
C. Particles must collide in any orientation: While collisions can happen in any orientation, not all collisions result in successful reactions. The correct orientation is necessary for the reactants to effectively interact and undergo a reaction.
D. A transfer of energy from the system to the surroundings must take place: While energy transfer can occur during a reaction, it is not a requirement for a reaction to take place. Energy changes can accompany a reaction, but they are not essential for the reaction itself.
Based on the explanation above, the correct answer is B. Particles must collide in the correct orientation.