Activation energy is the energy barrier that needs to be overcome for a reaction to proceed; the higher the activation energy, the slower the reaction. Activation energy can only be altered via a catalyst. Catalysts are chemical substances that lower the activation energy, allowing reactions to proceed faster. Other physical quantities such as temperature and pressure don’t alter the activation energy.

Reaction rate is a direct measure of the speed of a reaction. As mentioned, increasing activation energy will increase the barrier and, therefore, slow down the reaction.

Catalysts are chemical substances that decrease the activation energy, thereby increasing the reaction rate. They are commonly used in chemical reactions to drastically speed up reactions that might otherwise take hours or days to complete. Enzymes are biological catalysts that facilitate most of the biological reactions happening in our bodies. 

This question is asking about the relationship between activation energy of a reaction (kinetics) and the amount of products produced (equilibrium). Remember that altering the speed of a reaction (kinetics) does not change the equilibrium of the reaction. Increasing or decreasing activation energy (which alters the speed of reaction) will simply allow for the reaction to proceed slower or faster, respectively. It will not change the amount of products produced at the end.

Activation energy is the difference between the energy of the transition state and the energy of the reactant. Recall that activation energy is the energy barrier that needs to be overcome by a reaction. The transition state is a higher-energy, intermediary molecule that lies in between the reactants and products. It is created when reactants are in the process of becoming products. Therefore, to get to products, it is necessary to go through this high-energy transition state.

Activation energy is the energy needed to climb this energy “hill” (energy needed to go from reactants to transition state); therefore, the activation energy is the energy of the transition state (top of the energy hill/barrier) minus the energy of the reactant.

To answer this question, we have to consider an energy diagram for an exothermic reaction. We know the forward reaction is exothermic because the question states that energy is released. We are given the activation energy of the reaction (the energy difference between the activated complex, or transition state, and the reactants) and the energy released (the energy difference between the products and the reactants). In the reverse reaction we will be going from products to reactants as follows:

This means that the activation energy for reverse reaction will be higher (has to climb a higher hill from “products” to “activated complex”). Using the given information we can deduce that the activation energy () of the reverse reaction is the SUM of the activation energy of the forward reaction AND the energy released from the forward reaction.

The closest answer is . Note that the forward reaction is exothermic, whereas the reverse reaction is endothermic (energy is being consumed). The reverse reaction is endothermic because the reactant () has lower energy than the product ().

Recall that the only thing that can alter the activation energy of a reaction is the addition of a catalyst. Factors such as enthalpy, entropy, temperature, and pressure don’t change the activation energy.

Catalysts decrease the activation energy and increase the rate of reaction. They have no effect on the energy of the reactants. As mentioned, temperature will not alter the activation energy; however, increasing the temperature will speed up the reaction. This occurs because adding energy in the form of heat will increase the energy of individual molecules in the reaction and will allow more molecules to overcome the energy barrier. Note, however, that temperature does not change the energy barrier (activation energy).  Recall that changing activation energy has no effect on the equilibrium of the reaction; therefore, equilibrium constant does not depend on the activation energy.

It does not matter if the cell is galvanic or electrolytic; oxidation will always take place at the anode. This means that the nickel loses two electrons and is oxidized at the anode to generate nickel ions.

Nickel ions and iron are products, and are neither oxidized nor reduced during the reaction. Iron ions are reduced at the cathode to generate the iron product.

Oxidation takes place at the anode and reduction takes place at the cathode. You can remember this with the pneumonic "An Ox, Red Cat."

In the equation, zinc loses electrons. It goes from a neutral, elemental charge to a charge of . Since electrons are negative, a loss of electrons will cause an increase in charge. Because zinc loses electrons, it is oxidized. This will take place at the anode.

Reduction always occurs at the cathode, and oxidation always occurs at the anode. Since reduction is the addition of electrons, the electrons must flow toward the site of reduction.

In a galvanic cell the positive charge is on the cathode, while the negative charge is on the anode. Since a galvanic cell has a positive potential and is spontaneous, electrons freely flow down their potential gradient. The electrons, which are negatively charged, are traveling towards the cathode, which is positive charged, since opposites attract.

Reduction always occurs at the cathode, and oxidation always occurs at the anode. Since reduction is the addition of electrons, electrons must travel toward the site of reduction.

In an electrolytic cell the negative charge is on the cathode, while the positive charge is on the anode. Since an electrolytic cell requires energy to perpetuate the reaction, we are pushing the electrons against their potential gradient. The electrons, which are negatively charged, are traveling towards the cathode, which is also negatively charged.

Electrolytic cells use non-spontaneous reactions that require an external power source in order to proceed. The values between galvanic and electrolytic cells are opposite of one another. Galvanic cells have positive voltage potentials, while electrolytic voltage potentials are negative. Both types of cell, however, have oxidation occur at the cathode and reduction occur at the anode.