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1、物化动力学热（Physical and chemical kinetic heat）1. a partition plate divides a rigid container into left and right two chambers, and the pressure of the left ventricle is greater than that of the right chamber. Now the diaphragm is removed, and the pressure of the left and right chambers is balanced. If a
2、ll gases are used as systems, then U, Q and W are positive? For the negative? Or zero?Answer: because when the container is rigid, without considering the existence of other qualities under the action of system of power W? 0; the container is adiabatic, no energy exchange between the system and the
3、environment, so Q=0, according to the first law of thermodynamics? U = Q + W, the thermodynamic energy (thermal energy) the change of U = 0?.3. if the system passes through the following process, are the quantities of Q, W, Q, + W and U fully defined? Why?(1) to a closed system by an initial state t
4、hrough different ways to a final state (2) if the adiabatic conditions, the system from an initial state to a final state change a (1) a description of the physical and chemical process, including specific ways to process the initial state and final state of the process and experience, so that a giv
5、en process starting and final states can not fully explain the process. Q and W are dependent pathway (path-dependent), whose value depends on the initial state and final state of the process and concrete way, just because Q + W =? U, as long as the beginning and final state is determined, U? Q + W
6、is determined, so sure. (2) in the case where the initial and final states have been given, the process is defined as an adiabatic process, Q = 0, Q, and W = =, U, W and U are also determined.According to the characteristics of the reversible process, the 4. test points out which of the following pr
7、ocesses are reversible processes?(1) at room temperature and atmospheric pressure (101.325 kPa), water is evaporated into water vapor at the same pressure;(2) at 373.15 K and atmospheric pressure (101.325 kPa), at the same pressure as the evaporation of water vapor;(3) heat build-up by friction;(4)
8、use a dry cell to give light to the bulb;(5) in the freezing water condenses into ice at the same pressure;(6) mixing nitrogen and oxygen under isothermal and isobaric conditions.answer (1) not a reversible process. The reversible phase transition process should be a phase transition process at reve
9、rsible temperature and pressure,If the conditions are not satisfied, the reversible pressure at room temperature should be less than 101.325 kPa, and when the room temperature is 298 K, the saturated vapor pressure of water is 3168 Pa. (2) it may be a reversible process. (3) not a reversible process
10、. Heat generation by friction is a process of energy dissipation. (4) not a reversible process. An infinitesimal current cannot light a bulb. (5) it may be a reversible process. 273 K and 1 atm water can reversibly form ice. (6) it may be a reversible process. Reversible mixing can be achieved by th
11、e Funhoff balance box.7., open the door of the running refrigerator in the summer. If the close doors and windows (doors, windows and walls are not heat transfer), can the indoor temperature be lowered? Why? Can not. The refrigerator belongs to a heat engine. When the refrigerator is in normal opera
12、tion, the heat of the Q1 is removed from the refrigerator and discharged into the room through the use of electricity, and the value is Q2. According to the conservation of energy, there are Q, 2=Q, 1+W1; when the door of the refrigerator is opened, two heat sources (indoor air and air in the refrig
13、erator) are combined into a whole, called a single heat source. In the case of indoor air, the thermodynamic energy changes: U, =-Q, 1+Q, 2=Q, 1+ (Q, 1+W) = W. The upper type indicates that the thermodynamic change of the indoor air is equal to the electrical work value of the power supply, so the t
14、emperature of the air rises.2. can the two phases balance when the temperature of the two phases is the same but the pressure is different? If the pressure of the two phases is the same as the temperatureCan different phases achieve balance?solution in general, when the system reaches thermodynamic
15、equilibrium, the system will meet both thermal equilibrium, force balance, phase equilibrium and chemistryBalance. Specific to the phase equilibrium, the condition is that the chemical potential of each substance is the same in both phases. The factors affecting the chemical potential are temperatur
16、e and pressure. When the phase equilibrium is reached, the general temperature and pressure are equal. If the temperature is the same and the pressure varies, there is also the possibility of a phase equilibrium, such as an osmotic system; similarly, at the same pressure and temperature,There should
17、 also be a possibility of achieving a phase equilibrium.5., the difference between the point of the system and the point of phase. When is the point of the matter and the phase of the unity?system the point of matter represents the composition of the system, and the phase point represents the compos
18、ition of the system phase. When the system is single-phase, the two are coincident7. if the use of supercritical carbon dioxide fluid as extractant, what is the minimum working pressure? Can you do this at room temperature?CO2 the critical parameter of CO2 is Tc = 31.26, C, PC = 7.2 MPa, so the mini
19、mum pressure is 7.2 MPa. becauseFor Tc = 31.26, C is very close to typical room temperature values of 25 C, and thus CO2 supercritical fluid extraction can be operated at near room temperature.8. in a high pressure vessel, there is enough water to charge the vessel with nitrogen pressure to 10 MPa,
20、and then use Clausius-Does the Clapeyron equation calculate the boiling point of water?solution when the pressure reaches 10 MPa, the critical pressure of water is 22.129 MPa, almost close to normal, at this point the volume of waterIt can not be ignored that water vapor can not be regarded as an id
21、eal gas, so the boiling point of water can not be calculated by using the Clausius-Clapeyron equation.10. chloroform and methanol 50% (mass percent) of the system distillation, can be separated from pure chloroform?solution chloroform and methanol compose a constant boiling system, and the azeotropi
22、c composition is wCH3OH = 12.6%, and pure chloroform can be obtained by distillation13. please use the principle of extraction to explain the cleaning of glassware, why use a small number of methods? Choose when you do the extractionWhat is the principle of extractant?Conclusion the extraction of A
23、in the composition of A (R1, R2 and R3) gradually reduces to zero (R). If only one extraction is used, the content of Cui phase is limited.The main basis of selection of extractant is as follows: (1) the selectivity of extractant is large. There is also a close relationship between the number of tra
24、ys and the magnitude of the reflux ratio (which affects the diameter of the tower). (2) the solubility of the extractant to the separated component is greater than that of the trayLiquids form homogeneous, not stratified. (3) boiling point extractant should be separated fractions of high boiling poi
25、nt, otherwise the extraction agent is easy to volatilization loss of 4, fell from the top of the tower is better thermal stability and chemical stability, non-toxic, no corrosion to equipment, recycling 5 easy, cheap and easy to get.14. The connection line in phase diagram of the three component sys
26、tem is also called junction line. What is the meaning of the line? The tie and lever rules are linked 1.1. Whats the difference between a primary cell and an electrolytic cell?answer the primary cell converts chemical energy into electricity, and the electrolytic cell converts the electric energy in
27、to chemical energy.2. what are the factors that affect the conductivity of electrolyte solutions?answer the conductivity of electrolyte solution is related to the nature and concentration of electrolyte.3. why does conductivity have to be defined as molar conductivity? Whats the relationship between
28、 the two? answer because conductivity is related to concentration, the relationship between them is m/c.What is the practical significance of the conductance measurement of 4. electrolyte solutions?answer determination of ionization, solubility products, etc. ,5. how to realize the transformation of
29、 chemical energy into electric energy?Answer: through chemical power supply, chemical energy can be converted to electric energy.6. what are the conditions for a reversible cell?answer (1) the electrode reaction is reversible (2), and the electromigration process is reversible7. how do I write batte
30、ry expressions?answer (1) write out the composition of the electrodes; (2) write out the factors that affect the performance of the battery, such as the concentration, concentration, pressure, etc. of the material.8. what is the role of salt bridge? Choose salt bridge should pay attention to what th
31、e problem? a to eliminate the liquid junction potential. To pay attention to the choice of saltbridge: (1) the diffusion reaction with the electrolyte electrode material; (2) electrolyte solubility diffusion to be large enough; (3) diffusion of electrolyte anions and cations are similar.9. how is th
32、e electrode potential of a single electrode determined?a - single electrode electrode electric potential difference between solution to be determined, but can determine the relative potential of single electrode. The electrode is made up of a standard hydrogen electrode,The electromotive force of th
33、e cell is measured, i.e., the electrode potential of the electrode. If the electrode is reduced, the electrode potential is positive. If the electrode is oxidized, the electrode potential is negative. The standard hydrogen electrode measured electrodes10. what is the application of EMF measurement?
34、Determination of pH and so on.What is the cause of polarization of 11. electrodes?answer the reason for the polarization of the electrode is simple, because the electrode process is a very complex physical and chemical process, the rate of each element processInconsistent, resulting in the so-called
35、 polarization phenomenon. Do you have a system? solution a junction is a line connecting two balanced phases. The relation between the components of the equilibrium phase at the ends of the line is expressed by lever rules.2., there are two independent chemical reactions whose activation energies ar
36、e Ea, 1 Ea, 2, which temperature has a greater influence on the rate of reaction? If the front factor of the two reactions is equal, which reaction rate constant is greater?solution the activation energy has great influence on the temperature. The rate constant for reaction 1 is greater3., the rate
37、of chemical reaction increases with the increase of temperature. Please explain the phenomenon with the collision rate theory of reaction rate.solution the temperature has no influence on the collision frequency. When the temperature increases, the effective fraction increases, so the rate increases
38、 with the increase of temperature.5. ammonia synthesis reaction is an exothermic reaction, the lower temperature could improve the conversion rate, but the actual production of this reaction is in high temperature and high pressure and catalyst under the condition of the existence of, why? solution the reason for the selection of reaction conditions is to increase the reaction rate.