δE = QM-cmδt
(1) When water freezes under standard conditions, the kinetic energy of water remains unchanged and the potential energy of water decreases;
(2) I
δE = QM-cmδt
(1) When water freezes under standard conditions, the kinetic energy of water remains unchanged and the potential energy of water decreases;
(2) In general, the kinetic energy and potential energy of an object increase during heating;
(3) This problem is a special exothermic process, in which the potential energy of an object decreases more than the kinetic energy of an object increases.
Molecular kinetic energy and molecular potential energy are two inseparable parts of the internal energy of an object, and molecular kinetic energy and molecular potential energy have their own decisive factors. In the process of analyzing and calculating problems, the kinetic energy and potential energy of molecules should be analyzed and calculated separately.
[Idea 1] According to the concepts of molecular potential energy and kinetic energy of molecules, the change of molecular potential energy is determined by the average distance between molecules and the total number of molecules. This problem should be solved by using the heat of solution released in the process and the specific heat absorbed in the process of heating, and then by using the concepts of heat of solution and specific heat; The change of kinetic energy of molecules is determined by the total number of molecules and temperature, and this problem should be solved by specific heat.
[Viewpoint 2] According to the second law of thermodynamics, the work done in the process of doing work can be ignored, and the heat released in the process of heat transfer is the main contradiction of the problem. Then the energy conversion relationship in the process is analyzed by energy conversion and conservation law, and solved by equations.
[Idea 3] According to the laws of energy transformation and conservation, analyze the energy transformation relationship in the process and list the equations. According to the heat released in the melting process and the specific heat absorbed in the heating process, the corresponding equations are listed and solved.
★ Detailed explanation of the test questions: (according to the first idea)
The process of liquid solidification is a process in which the total molecular potential energy decreases, and the decrease amount should be qm, while the process of temperature increase is a process in which the average kinetic energy of molecules increases, that is, the total molecular kinetic energy increases, and the increase amount should be cm δ T. Because the whole body emits heat, the internal energy should be reduced, and the decrease amount should be equal to the decrease amount of total molecular potential energy minus the increase amount of total molecular kinetic energy.
That is, δ e = QM-cm δ t.
This problem is about the change of internal energy of an object, which is determined by the total kinetic energy and the total potential energy of the object molecule. Although potential energy and kinetic energy can be transformed into each other, there is no direct correspondence, so they should be analyzed and calculated separately.