"Molar Volume of Gas" Amount of Substance PPT Courseware

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"Molar Volume of Gas" Amount of Substance PPT Courseware

Part 1: Essential knowledge and foundation of literacy

1. Factors affecting the volume of matter

in conclusion:

(1) The volumes of different solid or liquid substances with the same number of particles under the same conditions_______;

(2) Under the same temperature and pressure conditions, the volume of any gas with the same number of particles is _____.

【Smart Judgment】

(1) 1 mol of different solid substances has different volumes, mainly due to different particle sizes. ()

Tips:√. The volume of solid matter mainly depends on the size and number of the constituent particles.

(2) When the pressure is constant, the higher the temperature, the greater the distance between gas molecules; when the temperature is constant, the greater the pressure, the greater the distance between molecules. ()

Tip:×. When the temperature is constant, the greater the pressure, the smaller the distance between gas molecules.

(3) Under normal temperature and pressure, the volumes of 1 mol O2 and 1 mol CO2 are almost the same. ()

Tips:√. At the same temperature and pressure, the distance between gas molecules is almost the same, so the volumes of 1 mol O2 and 1 mol CO2 are almost the same.

[Situation·Thinking] Basketball originated in Massachusetts, USA, and was created by James Naismith on December 21, 1891. It is a core event of the Olympic Games and is a hand-centered physical confrontation sport. When you use a pump to inflate a basketball, the gas is continuously pumped in, but the volume of the basketball does not change significantly.

What factors are related to the volume of a gas? If two gases have the same volume, do they necessarily contain the same number of molecules?

Tip: The main factor that affects the volume of gas is the distance between gas molecules. When you pump up the basketball, the volume of the basketball will not change greatly because the distance between gas molecules is constantly shrinking. Two gases have the same volume but do not necessarily contain the same number of molecules. Because gas volume is greatly affected by temperature and pressure, when the temperature and pressure are different, the amount of material in two gases with the same volume is not necessarily the same, so the number of molecules contained is not necessarily the same.

2. Gas molar volume

【Smart Judgment】

(1) The gas molar volume is a certain value, and it must be 22.4 L·mol-1 no matter what the conditions are. ()

Tip:×. The molar volume of gas is affected by temperature and pressure, and the values ​​are different at different temperatures and pressures.

(2) The volume occupied by 1 mol CCl4 is 22.4 L under standard conditions. ()

Tip:×. Under standard conditions, CCl4 is a liquid and gas molar volume cannot be applied.

【Situation·Thinking】

CO2 is an essential raw material for plant photosynthesis. A research institution measured the CO2 content as shown in the figure.

What is the volume of CO2 per cubic meter of gas in the sample measured this time?

Tip: 44.8 L. It can be concluded from the illustration that the measurement was carried out under standard conditions, and the content of CO2 is 88 g·m-3, so the volume of CO2 contained is ______×22.4 L·mol-1=44.8 L.

3. Avogadro’s Law

1. Content: At the same temperature and pressure, the same volume of any gas contains the same number of particles.

2. Scope of application: Avogadro's law and its corollary are only applicable to gases, which can be single gases or mixed gases. They are not applicable to solids and liquids.

3. The rule of "three similarities determine one": as long as there are "three similarities" among the same temperature, same pressure, same volume, and the same number of molecules, there must be a "fourth similarity".

【Smart Judgment】

(1) Under the same temperature and pressure, the same volume of any gas contains the same number of atoms. ()

Tip:×. At the same temperature and pressure, the same volume of any gas contains the same number of molecules, and different molecules may contain different atoms.

(2) Under the same temperature and pressure, the same volume of matter contains the same number of molecules. ()

Tip:×. Avogadro's law only applies to gaseous substances, not liquid or solid substances.

Gas molar volume PPT, part 2 content: key abilities and literacy formation

Knowledge point 1: Gas molar volume and related calculations

[Key points to clarify doubts]

1. Gas molar volume under standard conditions

(1) 1 condition: it must be a standard condition. Under non-standard conditions, the volume of 1 mol of gas is not necessarily 22.4 L. Therefore, when using the molar volume of a gas, you must clearly see the state of the gas.

(2) 1 state: must be gas. Substances such as water, alcohol, and CCl4 are not gases under standard conditions.

(3) 2 data: “1 mol” and “about 22.4 L”.

2. Applicable range of gas molar volume

The applicable range of gas molar volume is gas, which can be a single gas or a mixed gas. For example, the volume of a mixed gas of 0.2 mol H2 and 0.8 mol O2 under standard conditions is approximately 22.4 L. It should be noted that chemical reactions cannot occur between the gases in the mixed gas.

3. Calculation of gas molar volume

[Error-prone reminder] (1) When the number of gas molecules, temperature, and pressure are constant, the size of the gas volume is determined by the average distance between gas molecules, regardless of the type of molecules.

(2) The gas molar volume only applies to gaseous substances and has nothing to do with the type of gas. As long as the temperature and pressure are constant, the gas molar volume will be constant.

(3) At the same temperature and pressure: the molar volume Vm of any gas is the same, but it is not necessarily equal to 22.4 L·mol-1.

(4) Do not confuse standard conditions with normal temperature and pressure. They have the same pressure but different temperatures. Because the distance between gas molecules increases as the temperature increases, the molar volume of gas at normal temperature and pressure is larger than the molar volume of gas under standard conditions.

(5) Gas molar volume cannot be understood as volume. The unit of volume is L or m3, while the unit of gas molar volume is L·mol-1 or m3·mol-1.

Knowledge point 2: Avogadro’s law and its corollary

[Key points to clarify doubts]

1.Avogadro’s law

(1) Content: At the same temperature and pressure, any gas of the same volume contains the same number of particles.

(2) Scope of application: Avogadro's law and its corollary are applicable to gases, which can be single gases or mixed gases. They are not applicable to solids and liquids.

(3) The rule of "three similarities determine one": as long as there are "three similarities" among the same temperature, same pressure, same volume, and the same number of molecules, there must be a "fourth similarity".

2. Corollary to Avogadro’s law

【Think·Discussion】

(1) Do 1 L H2 and 1 L O2 contain the same number of molecules? Why?

Tip: Not necessarily. If at the same temperature and pressure, the number of molecules in 1 L H2 and 1 L O2 is the same; if at different temperatures and different pressures, the number of molecules in 1 L H2 and 1 L O2 is not necessarily equal.

(2) Two identical gas bottles, one containing 1 mol of oxygen and the other containing 2 mol of hydrogen, what is the relationship between the gas pressures in the two gas bottles at the same temperature?

Tip: According to the inference of Avogadro's law, when the same temperature and volume are the same, the pressure of a gas is proportional to the amount of its substance. The ratio of the pressures of oxygen and hydrogen in the two gas bottles is 1:2.

【Case Demonstration】

[Typical example] (2019 Shijiazhuang Senior High School Test) Two closed containers with the same volume are filled with O2 and O3 gases respectively. When the temperature and density of the gases in the two containers are equal, the following statement is correct ()

A. The pressures of the two gases are equal

B.O2 has smaller mass than O3

C. The number of molecules of the two gases is equal

D. The number of oxygen atoms in the two gases is equal

Keywords: Free download of PPT courseware for high school chemistry compulsory course I of the People's Education Press, PPT download of gas molar volume, PPT download of quantity of substance, .PPT format;

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Update Time: 2024-10-03

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