Melting occurs because the skates apply pressure to the ice. Due to the negative slope of solid-liquid equilibrium line for water, increased pressure results in a change from solid to liquid. None of the other answer choices do not have to do with the equilibrium between solid and liquid.

Sweating reduces skin temperature because the sweat that is secreted to the skin evaporates, which is an endothermic process. Thus, heat is absorbed from the body and skin to drive the evaporation of the sweat on the skin.

Bond dissociation energy is the energy associated with a bond within a molecule. This means that bond dissociation energy is measured for intramolecular bonds. All covalent and ionic bonds are considered intramolecular bonds, and are generally quite permanent. Ionic bonds and polar covalent bonds can help develop dipoles in a molecule, which later facilitate intermolecular interactions.

Hydrogen bonds are intermolecular bonds, which do not have associated bond dissociation energies because these type of bonds are temporary, and are formed between different molecules.

If there was more mass (in grams) of the element in container 1 than there was in container 2, we would expect container 1 to undergo a smaller temperature change compared to container 2. This is justified by the equation , where m is the mass.

Rewritten as , we can see that a larger mass would result in a smaller temperature change. Remember that q is held constant between the two containers.

If element 2 expelled some of its energy to the surroundings in the form of work (expanding the container), it could explain why it had a smaller temperature change. In addition, different phases of an element have different specific heat capacities. This can also explain the difference in temperature between the two element samples.

Convection describes heat transfer through a fluid medium, such as a gas or liquid. In this case, the burning tree transfers heat to the air, which transfers the heat to the other tree.

Conduction requires direct contact, which would occur if a burning tree fell into another tree. Radiation is the electromagnetic transfer of heat, such as the sun's heat that travels to Earth, and does not require matter to transfer. Transduction is not a mechanism for heat transfer.

For the MCAT, remember "ANOX REDCAT." This will remind you that oxidation occurs at the anode, and reduction occurs at the cathode.

Since solid zinc (Zn) is giving up two electrons in the reaction, it is being oxidized. The iron ion (Fe²⁺) is accepting the two electrons, so it is being reduced.

An electrochemical cell undergoes two half-cell reactions (one oxidation reaction and one reduction reaction). Each half-cell reaction occurs either in a cathode or an anode; therefore, an electrochemical cell always has a cathode and an anode. Recall that there are two types of electrochemical cells: a galvanic cell and an electrolytic cell. Regardless of the type of the electrochemical cell, the reduction half-cell reaction always occurs in the cathode and the oxidation half-cell reaction always occurs in the anode; therefore, both galvanic and electrolytic cells have reduction occurring in the cathode and oxidation occurring in the anode. 

In both galvanic and electrolytic cells, electrons flow from the anode to the cathode. Anodes have free electrons because electrons are products of an oxidation reaction whereas cathodes require electrons because electrons are reactants of a reduction reaction; therefore, the free electrons flow from the anode to the cathode where they are used up in the reduction reaction. 

Cathodes are found in both galvanic and electrolytic cells. Recall the cathodes are the site of reduction half-reaction and anodes are the site of oxidation half-reaction.

The cathode is the site of reduction half-reaction, whereas the anode is the site of the oxidation half-reaction. In a reduction reaction molecules acquire electrons, whereas in an oxidation reaction molecules lose electrons. Electrons act as reactants during reduction reactions in the cathode, whereas they serve as products during oxidation reactions in the anode.

In the reaction, a sodium ion (with a charge of ) becomes a neutral sodium metal. This means that the sodium ion gained an electron and was reduced in the reaction. On the other hand, copper metal went from a neutral molecule to a copper ion with a charge of ; therefore, copper metal lost two electrons and was oxidized in the reaction. Recall that the reduction half-reaction always occurs in the cathode and the oxidation half-reaction always occurs in the anode. This means that the sodium half-cell will be found at the cathode and the copper half-cell will be found at the anode. 

To solve this question, we don’t need to know the electrochemical cell potential of the reaction. The electrochemical cell potential signifies whether the reaction is spontaneous (positive cell potential) or nonspontaneous (negative cell potential). A spontaneous reaction will occur in a galvanic cell and a nonspontaneous reaction will occur in an electrolytic cell. Remember that, regardless of the type of electrochemical cell, the reduction half-reaction always occurs at the cathode and the oxidation half-reaction always occurs at the anode; therefore, in both cells, the sodium half-cell will be in the cathode and the copper half-cell will be in the anode.

Electron flow, especially the electrical energy associated with electron flow, is an important characteristic of an electrochemical cell. In a galvanic cell, electrical energy is harnessed from a spontaneous chemical reaction and is used to drive other unfavorable processes. In an electrolytic cell, electrical energy is supplied by an outside voltage source that is used to drive a nonspontaneous chemical reaction.

Recall that cathodes are the site of reduction and anodes are the site of oxidation. Electrons are used up (reactants) in a reduction reaction and electrons are produced (products) in an oxidation reaction; therefore, anodes produce and have an excess of free electron,s whereas cathodes use and have a deficiency of free electrons. Since there are fewer electrons in the cathode, the electrons in an electrochemical cell will flow from the anode to the cathode.