AP化学词汇（八）

　　对于中国学生来说，一门优秀的AP成绩不仅对学生的申请有所帮助，还能为以后融入美国的学习生活打下基础。对于学习AP的同学来说，掌握词汇是至关重要的，词汇量不足将对答题速度和对标题理解都会影响。新东方在线AP盘点了各科目的词汇，今天为大家带来的是：AP化学词汇(八)，建议同学们收藏。

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　　AP化学词汇(八)

　　standard state

　　condition

　　标况

　　In chemistry, the standard state of a material (pure substance, mixture or solution) is a reference point used to calculate its properties under different conditions.

　　galvanic cells

　　原电池

　　A galvanic cell, or voltaic cell, named after Luigi Galvani, or Alessandro Volta respectively, is an electrochemical cell that derives electrical energy from spontaneous redox reactions taking place within the cell.

　　anode

　　(原电池)阴极

　　An anode is an electrode through which conventional current flows into a polarized electrical device. A common mnemonic is ACID for "anode current into device". The direction of (positive) electric current is opposite to the direction of electron flow: (negatively charged) electrons flow out the anode to the outside circuit.

　　cathode

　　(原电池)阳极

　　A cathode is the electrode from which a conventional current leaves a polarized electrical device. This definition is sometimes remembered using the mnemonic CCD for cathode current departs. A conventional current describes the direction in which positive electronic charges move. Electrons have a negative charge, so the movement of electrons is opposite to the conventional current flow.

　　intensive property

　　强度性质/内涵性质

　　Physical properties of materials and systems can often be categorized as being either intensive or extensive quantities, according to how the property changes when the size (or extent) of the system changes. According to IUPAC, an intensive property is one whose magnitude is independent of the size of the system, whereas an extensive property changes as the amount of size of the material changes.

　　spontaneity

　　自发性

　　A spontaneous process is one that occurs on its own, without any energy input from the outside.

　　Gibbs free energy

　　吉布斯自由能

　　In thermodynamics, the Gibbs free energy (IUPAC recommended name: Gibbs energy or Gibbs function; also known as free enthalpy to distinguish it from Helmholtz free energy) is a thermodynamic potential that measures the maximum or reversible work that may be performed by a thermodynamic system at a constant temperature and pressure (isothermal, isobaric).

　　Nernst equation

　　能斯特方程

　　In electrochemistry, the Nernst equation is an equation that relates the reduction potential of a half-cell (or the total voltage, i.e. the electromotive force, of the full cell) at any point in time to the standard electrode potential, temperature, activity, and reaction quotient of the underlying reactions and species used.

　　lithium-ion batteries

　　锂电池

　　The electrodes of a lithium-ion battery are made of lightweight lithium and carbon. Lithium is also a highly reactive element, meaning that a lot of energy can be stored in its atomic bonds. This translates into a very high energy density for lithium-ion batteries. Here is a way to get a perspective on the energy density. A typical lithium-ion battery can store 150 watt-hours of electricity in 1 kilogram of battery.

　　fuel cells

　　燃料电池

　　A fuel cell uses the chemical energy of hydrogen or another fuel to cleanly and efficiently produce electricity. If hydrogen is the fuel, electricity, water, and heat are the only products.

　　electrolytic cells

　　电解池

　　An electrolytic cell is an electrochemical cell that undergoes a redox reaction when electrical energy is applied. It is most often used to decompose chemical compounds, in a process called electrolysis—the Greek word lysis means to break up. When electrical energy is added to the system, the chemical energy is increased.

　　electroplating

　　电镀

　　Electroplating is a process that uses electric current to reduce dissolved metal cations so that they form a coherent metal coating on an electrode. The term is also used for electrical oxidation of anions onto a solid substrate, as in the formation silver chloride on silver wire to make silver/silver-chloride electrodes.

　　salt bridge

　　盐桥

　　A salt bridge, in electrochemistry, is a laboratory device used to connect the oxidation and reduction half-cells of a galvanic cell (voltaic cell), a type of electrochemical cell. It maintains electrical neutrality within the internal circuit, preventing the cell from rapidly running its reaction to equilibrium.

　　reaction rate

　　反应速率

　　The reaction rate (rate of reaction) or speed of reaction for a reactant or product in a particular reaction is intuitively defined as how fast or slow a reaction takes place. For example, the oxidative rusting of iron under Earth's atmosphere is a slow reaction that can take many years, but the combustion of cellulose in a fire is a reaction that takes place in fractions of a second.

　　instantaneous rate

　　瞬时速度

　　The instantaneous rate of change measures the rate of change, or slope, of a curve at a certain instant. Thus, the instantaneous rate of change is given by the derivative.

　　collision model

　　碰撞模型

　　A collision model is a model of the rate of a reaction showing how the rate is proportional to the number of collisions of reactant molecules.

　　transition state

　　过渡态

　　The transition state of a chemical reaction is a particular configuration along the reaction coordinate. It is defined as the state corresponding to the highest potential energy along this reaction coordinate. At this point, assuming a perfectly irreversible reaction, colliding reactant molecules always go on to form products. It is often marked with the double dagger symbol (‡).

　　activation energy

　　活化能

　　In chemistry, activation energy is a term introduced in 1889 by the Swedish scientist Svante Arrhenius to describe the minimum energy which must be available to a chemical system with potential reactants to result in a chemical reaction. Activation energy may also be defined as the minimum energy required to start a chemical reaction.

　　rate-determining

　　step

　　限速步骤

　　The rate determining step is the slowest step of a chemical reaction that determines the speed (rate) at which the overall reaction proceeds.

　　logarithm

　　对数

　　In mathematics, the logarithm is the inverse operation to exponentiation. That means the logarithm of a number is the exponent to which another fixed value, the base, must be raised to produce that number. In simple cases the logarithm counts repeated multiplication. For example, the base 10 logarithm of 1000 is 3, as 10 to the power 3 is 1000; the multiplication is repeated three times.

　　rate constants

　　速率常数

　　The rate constant is a proportionality factor in the rate law of chemical kinetics that relates the molar concentration of reactants to reaction rate. It is also known as the reaction rate constant or reaction rate coefficient and is indicated in an equation by the letter k.

　　unit

　　单位

　　A quantity chosen as a standard in terms of which other quantities may be expressed. E.g. “a unit of measurement"

　　half-life

　　半衰期

　　Half-life (t1⁄2) is the time required for the amount of something to fall to half its initial value. The term is very commonly used in nuclear physics to describe how quickly unstable atoms undergo decay, or how long stable atoms survive, and it is also used more generally of any type of exponential or non-exponential decay. The converse of half-life is doubling time.

　　unimolecular

　　单分子的 adj. Consisting of or involving a single molecule.

　　reaction mechanism

　　反应机制

　　In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical change occurs. A chemical mechanism describes in detail exactly what takes place at each stage of an overall chemical reaction (transformation).

　　reaction

　　intermediate

　　反应中间物

　　An intermediate or reaction intermediate is a substance formed during a middle step of a chemical reaction between reactants and the desired product. Intermediates tend to be extremely reactive and short-lived, so they represent a low concentration in a chemical reaction compared with the amount of reactants or products.

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