45 . D
If the reverse reaction is exothermic, the equation can be written as such:If you remove heat, the equilibrium will shift to the left in an attempt to produce more heat.46 . A
An increase or decrease of entropy is easy to predict when the chemical reactions involve
gases. If there are more moles of gas on the products side than on the reactants side, there is
an increase in entropy. If there are fewer moles of gas on the products side than on the
reactants side, there is a decrease in entropy. For choice A, there are two moles of gas on the
reactants side and one mole of gas on the products side—there is, therefore, a decrease in
entropy for this reaction.
47 . D
Mendeleev discovered the properties of the elements and how they had regular intervals, and
formulated the first periodic table. Faraday found that chemical changes could occur when an
electrical current was sent through certain chemical solutions. Millikan did the famous oil drop
experiment that determined the charge on an electron. Rutherford discovered the nucleus by
striking thin metal foils with alpha particles.
48 . A
Electrochemical reactions that are nonspontaneous (those having a positive ∆G) can be driven
to completion by passing an electric current through the solution. This process is known as
electrolysis and the cell is called an electrolytic cell. In an electrolytic cell, the anode is
positively charged and the cathode is negatively charged—the opposite of a galvanic cell. Just
as with a galvanic cell, oxidation occurs at the anode and reduction occurs at the cathode.
49 . C
Ionization energy is defined as the amount of energy required to remove an electron from a
given species. Ionization energy is usually expressed in energy per particle (as it is here) or in
energy per mole, and energy, in turn, is usually expressed in electron volts (eV), joules, or
kilojoules. The first ionization energy of an element is the energy required to remove an
electron from a neutral atom of that element, while the second ionization energy is the energy
required to remove a second electron, i.e., to remove an electron from the +1 cation. A
particularly useful piece of logic/knowledge here is that it will be more difficult to remove an