Holt Ch 17 PPt

Multiple Choice

Why is it important to understand reaction mechanisms in chemistry?

• Because it helps predict the outcome of reactions

• Because it makes chemistry easier to memorize

• Because it is required for all laboratory work

• Because it is only relevant for organic chemistry

Multiple Select

Which of the following statements about reaction mechanisms are correct?

• A reaction mechanism may involve several simple steps.

• Intermediates appear in the net chemical equation.

• Experiments help determine the probable sequence of steps in a mechanism.

• A homogeneous reaction has reactants and products in a single phase.

Multiple Choice

Which of the following factors must be present for a reaction to occur, according to the kinetic-molecular theory?

• Molecules must collide with sufficient energy.

• Molecules must be in a liquid state.

• The reaction must be exothermic.

• The products must have higher energy than the reactants.

Open Ended

Explain why the reaction H₂ + I₂ → 2HI does not need to occur in a single step. What might be the significance of stepwise reactions in understanding chemical processes?

Multiple Choice

According to collision theory, what must happen for a chemical reaction to occur between two substances?

• Their particles must collide with enough energy and proper orientation

• Their particles must be in the same phase

• Their particles must have the same mass

• Their particles must be ions

Open Ended

Describe how the speed of a chemical reaction is influenced by the energy pathway and molecular interactions, as discussed in the lesson.

Multiple Choice

Which of the following best describes a reaction mechanism?

• The overall chemical equation for a reaction

• The step-by-step sequence of reactions by which the overall chemical change occurs

• The rate at which a reaction proceeds

• The energy released during a reaction

Open Ended

Explain why reaction intermediates do not appear in the net chemical equation, using the formation of HI as an example.

Multiple Choice

Which of the following is necessary for a chemical reaction to occur between colliding particles?

• The particles must collide with sufficient energy and proper orientation.

• The particles must be of the same type.

• The particles must be moving slowly.

• The particles must be in a liquid state.

Multiple Choice

Which arrangement of HI molecules will result in an effective collision for the reaction of H2 and I2?

• The arrangement where the correct atoms are aligned for bond formation.

• Any random arrangement of HI molecules.

• An arrangement where the molecules are far apart.

• An arrangement with low energy collisions.

Multiple Select

According to collision theory, which of the following are reasons why a collision between reactant molecules may fail to produce a new chemical species?

• The collision is not energetic enough to supply the required energy.

• The colliding molecules are not oriented in a way that enables them to react.

• The reactants are in different phases.

• The temperature is too high.

Open Ended

Explain why the reaction between hydrogen and oxygen to form water does not occur spontaneously at room temperature, even though it is exothermic.

Multiple Choice

Which of the following best describes the role of activation energy in the decomposition of HI and HBr as shown in the diagrams?

• It is the minimum energy required to start the reaction.

• It is the energy released during the reaction.

• It is the energy of the products.

• It is the energy of the reactants.

Multiple Choice

What does the symbol Ea represent in the context of the reaction energy diagram?

• Activation energy for the forward reaction

• Activation energy for the reverse reaction

• Change in energy between reactants and products

• Energy of the products

Multiple Choice

Compare the activation energy for the forward and reverse reactions in the exothermic reaction shown. Which statement is correct?

• The activation energy for the forward reaction is lower than for the reverse reaction.

• The activation energy for the forward reaction is higher than for the reverse reaction.

• Both activation energies are equal.

• Activation energy is not required for the reverse reaction.

Open Ended

Explain the concept of the activated complex and its significance in chemical reactions.

Multiple Choice

During the formation of HI, how many activation energy peaks (activated complexes) are present according to the energy diagram?

• One

• Two

• Three

• Four

Open Ended

Explain why a powder does not burn when placed in a jar over a flame, but bursts into flames when dispersed in the flame.

Multiple Select

Which of the following are objectives for studying reaction rates, as listed in the slides?

• Define chemical kinetics

• Discuss factors that influence reaction rate

• Define catalyst and discuss two types

• Explain the periodic table trends

Open Ended

Describe how the concepts of activation energy and reaction rate are related, using information from the reaction energy diagram and definitions provided.

Multiple Choice

What is the area of chemistry called that is concerned with reaction rates and reaction mechanisms?

• Thermodynamics

• Chemical kinetics

• Stoichiometry

• Electrochemistry

Multiple Choice

The reaction H2 + I2 → 2HI can occur in multiple steps. Which of the following is NOT a possible stepwise reaction for this process?

• H2 → 2H, 2H + I2 → 2HI

• I2 → 2I, 2I + H2 → 2HI

• H2 + I2 → 2HI in a single step

• I2 → 2I, H2 + I → HI + H, H + I → HI

Open Ended

What did you find most interesting or challenging about the different possible stepwise reactions for the formation of HI from H2 and I2?