Kinetics and Thermodynamics Review

Front

What is the relationship between ΔH and ΔS for a spontaneous reaction?

Back

For a reaction to be spontaneous, the combination of ΔH (enthalpy change) and ΔS (entropy change) must be such that the Gibbs free energy change (ΔG) is negative. Specifically, a reaction is non-spontaneous when ΔH is positive and ΔS is negative.

Front

What does +ΔH and -ΔS indicate about a reaction?

Back

+ΔH (endothermic) and -ΔS (decrease in disorder) indicate that the reaction is non-spontaneous under all conditions.

Front

What is activation energy?

Back

Activation energy is the minimum energy required for a chemical reaction to occur. It is represented by the letter 'A' in reaction diagrams.

Front

How does a phase change from gas to solid affect entropy?

Back

The transition from CO2(g) to CO2(s) results in a decrease in entropy because the gas molecules become more ordered in the solid state.

Front

What is collision theory?

Back

Collision theory states that for a reaction to occur, reactant molecules must collide with sufficient energy and the correct orientation.

Front

What is the significance of the correct orientation of molecules in a reaction?

Back

Correct orientation of molecules during a collision is crucial for the formation of products, as it allows for effective overlap of orbitals.

Front

What is an activated complex?

Back

An activated complex is a temporary, unstable arrangement of atoms that occurs during the transition from reactants to products in a chemical reaction.

Front

What is the difference between a slow and fast step in a reaction mechanism?

Back

A slow step is the rate-determining step that limits the overall reaction rate, while a fast step occurs quickly and does not significantly affect the overall rate.

Front

What is a reaction pathway diagram?

Back

A reaction pathway diagram visually represents the energy changes during a chemical reaction, showing the energy of reactants, products, and the activation energy.

Front

What does a negative ΔG indicate?

Back

A negative ΔG (Gibbs free energy change) indicates that a reaction is spontaneous under the given conditions.