I. Thermometer

1, thermometer

(1) The concept of temperature: The degree of heat and cold of an object is called temperature.

(2) Temperature measuring tool: thermometer.

(3) Range: the highest and lowest temperature that can be measured.

(4) Divided value: the value represented by the smallest cell.

(5) The most basic point to note is that the temperature of the measured object cannot exceed the range of the thermometer.

2. Temperature grade:

(1) Celsius temperature: symbol T, unit symbol℃, Celsius temperature regulation: the temperature of ice-water mixture is 0℃, the temperature of boiling water at standard atmospheric pressure is 100℃, and it is divided into 100 equal parts between 0℃ and 100℃, and each equal part is.

(2) The body temperature of a normal person is 37℃.

3. Thermometer:

(1) There is a thin tube between the glass bulb and the straight glass tube of the thermometer. When the mercury shrinks, the silver in the shrinking mouth will be automatically disconnected first, and the mercury in the straight tube cannot return to the glass bulb. Therefore, mercury should be put back into the glass bulb before each use of the thermometer.

(2) The measuring range of the thermometer is 35-42℃, and the dividing value is 0. 1℃.

4. Method of measuring liquid temperature with thermometer

(1) All glass bubbles of the thermometer invade the liquid to be measured, and do not touch the bottom and wall of the container.

(2) After the glass bulb of the thermometer invades the liquid to be measured, read again after the indicator is stable.

(3) When reading, the glass bulb of the thermometer should stay in the liquid, and the line of sight should be flush with the upper surface of the liquid column in the thermometer. Reminder: a thermometer can read without a human body, and an ordinary thermometer can't read without a measured object.

Second, melting and solidification.

1, melting and solidification: the change from solid to liquid is called melting, and the change from liquid to solid is called solidification. If ice turns into water, it belongs to melting; The freezing of water belongs to solidification. Reminder: integration should not be confused. The former means that a substance has a solid state and becomes a liquid state; The latter refers to the process in which some solutes are dissolved in the solvent.

2. Melting point and freezing point

(1) Crystal and amorphous: Crystal has a fixed melting point, such as hypo, ice, timely, crystal, salt, naphthalene and various metals; Amorphous crystals have no fixed melting point, such as rosin, glass, asphalt, etc.

(2) Melting point and freezing point: crystals have a certain melting temperature, which is called melting point; The freezing temperature is called freezing point. The freezing point of the same crystal substance is the same as its melting point.

Exercise: Among the following substances, all belong to crystal (C)

A Haibo, when appropriate, glass B salt, naphthalene, asphalt C Haibo, ice, crystal D rosin, glass and asphalt.

3. Melting absorbs heat and solidification releases heat.

Melting characteristics of (1) crystal: the melting process absorbs heat, and the temperature (melting point) remains unchanged. Melting conditions: ① the temperature reaches the melting point; Continuously absorb heat from the outside.

(2) Amorphous melting characteristics: the melting process absorbs heat and the temperature gradually increases.

(3) Crystal solidification characteristics: the solidification process is exothermic and the temperature (freezing point) remains unchanged. Conditions: ① The temperature reaches freezing point; (2) Constantly releasing heat to the outside world.

(4) The characteristics of amorphous solidification: exothermic, and the temperature keeps decreasing.

Third, vaporization and liquefaction.

1, vaporization and liquefaction phenomena

(1) vaporization: the process of changing a substance from a liquid state to a gas state is called vaporization; For example, if water is spilled on the ground, it will dry after a while; Wet clothes are dried by the sun, etc.

(2) Liquefaction: The process of changing a substance from a gaseous state to a liquid state is called liquefaction. For example, in winter, you can see people outdoors constantly exhaling "white gas"; The "white gas" often seen when boiling water.

2. Boiling phenomenon

(1) Boiling: The interior and surface of the liquid are violently vaporized at the same time.

(2) Boiling point: the temperature at which the liquid boils. Different liquids have different boiling points.

(3) Boiling conditions: ① At 1 standard atmospheric pressure, the boiling point of water is 100℃. (2) To keep the liquid boiling, the liquid must be heated, but the temperature of the liquid did not rise during the boiling process.

3. Evaporation:

(1) Conditions of evaporation: It can occur anywhere and at any temperature.

(2) Characteristics of evaporation: evaporation is a vaporization phenomenon that only occurs on the surface of liquid.

(3) Factors affecting evaporation rate: ① Liquid temperature. The higher the liquid temperature, the faster the evaporation. ② Surface area of liquid. The larger the stool area, the faster the evaporation. ③ Flow velocity of air on the liquid surface: The faster the flow, the faster the evaporation.

(4) The method of controlling evaporation speed: accelerating evaporation; Increase the liquid temperature; Increase the surface area of liquid; Accelerate the air flow on the liquid surface. Slow evaporation: Take the opposite measures.

(5) Evaporation has refrigeration function: the process of absorbing heat by evaporation will lower the temperature of liquid and itself.

Exercise: Among the following measures, (c) can make evaporation faster.

Wrap the vegetables in plastic wrap and put them in the refrigerator. Cover the ink bottle. Blow dry hair with a hair dryer. Put fresh oranges in a plastic bag.

Step 4 Liquefy

(1) Two methods of liquefaction: ① cooling; ② Compressed volume.

(2) When liquefied, heat should be released. Liquefaction is the reverse process of gasification, which absorbs heat and releases heat.

5. Judgment of liquefaction phenomenon

(1) "White gas" and "fog" are liquefaction phenomena. For example, fog is an exothermic process, and water vapor in the air cools to form fog.

(2) "Sweat" is a liquefaction phenomenon. For example, there is a layer of water droplets hanging on the surface of the tap water pipe, which is an exothermic process.

Fourth, sublimation and sublimation.

1, sublimation phenomenon: The process that a substance directly changes from a solid state to a gas state is called sublimation, and sublimation absorbs heat. Such as white fog on the stage, is due to the sublimation of dry ice into gas by heating. Sublimation absorbs heat, so that the moisture in the nearby air evaporates into small water droplets-white fog.

2. Sublimation phenomenon: The process that a substance directly changes from a gaseous state to a solid state is called sublimation, which gives off heat. For example, the phenomenon of "rime" on branches in winter and the phenomenon of ice flowers on the inner surface of windows. 3 sublimation and sublimation phenomenon judgment