# Physics Chapter 8 Kinetic Model Of Matter

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Physics Chapter 8 Kinetic Model Of Matter

## 1. About It

### 1.1. What It Is

1.1.1. The Kinetic Theory Of Matter

1.1.1.1. All matter is made up of a large number of tiny atoms or molecules which are in continuous and random motion

### 1.2. What It Originates From

1.2.1. Brownian Motion

1.2.1.1. Who Discovered It

1.2.1.1.1. Scottish Botanist Robert Brown

1.2.1.2. How Was It Discovered

1.2.1.2.1. Tiny grains of pollen where constantly moving in a random manner when observed under a microscope

1.2.1.3. What It Entails To

1.2.1.3.1. Irregular or random motion of particles are the result of particles bring hit by other unseen fast moving molecules, thus Brownian Motion provides evidence of the movement of molecules

## 2. Factors Acffecting It

### 2.1. States Of Matter

2.1.1. Solid

2.1.1.1. -Fixed Shape - Molecules are arranged close together in a regular pattern - Not Compressible - Molecules are arranged close together and there is little space between them -Does not flow easily - There are balanced forces between the molecules which hold them in fixed positions - The molecules can only vibrate about their fixed positions, alternately attracting and repelling one another - The strong attractive forces prevent the molecules from leaving their positions while the repulsive forces which act when they are too close to each other prevent them from collapsing. This explains why a solid has afixed shape and a fixed volume - When a solid is heated, the molecules gain energy and vibrate. The separation between molecules increases slightly and the solid expands

2.1.2. Liquid

2.1.2.1. -Fixed Volume But No Fixed Shape - The molecules are not arranged in a regular pattern and are slightly further apart than in solids - The attractive forces between the molecules make it difficult for the molecules to leave the liquid and thus liquids have a definite volume - Not Easily Compressible - Liquids cannot be compressed as the molecules are close togethre and there is little space between them - Assumes Shape Of The Container Which It Occupies - Though there are still forces between the molecules, they are not held in a fixed position. Because of this, the molecules move among one another througout the liquid. That is why liquids from and take the shape of their container - Flows Easily - The molecules vibrate to and fro, alternately attracting and repelling one another whith forces that can be just as strong as those in a solid - When heated, the molecules vibrate and move about vigorously. Thus the liquid expands only to a very slight extent

2.1.3. Gas

2.1.3.1. - No Fixed Shape And No Fixed Volume - Assumes The Shape And Volume Of Its Container - The intermolecular forces act only at moments of collision. Otherwise, the molecules are far apart that the intermolecular forces become negligible. Therefore , a gas is free to fill a container completely - Highly Compressible - The molecules are far apart - Gas can be comprseed because the molecules are sparse and there is a lot of space between them - Flows Easily - The molecules move randomly at high speed, colliding with one another and with the walls of the container

### 2.2. Temperatue, Volume and Pressure

2.2.1. Temperature

2.2.1.1. When temperature increases, thermal energy is transferred to the molecules and the molecules gain kinetic energy. This will cause the molecues to move faster

2.2.2. Pressure

2.2.2.1. When randomly moving gas molecules hit the walls of the container, they exert a force on the wall

2.2.3. Scenarios

2.2.3.1. Pressure increases as Temperature Increases

2.2.3.1.1. For fixed mass of gas at a constant volume, when the temperature of the gas in the container increases, the molecules move faster and hit the walls more frequently and more violently (With greater force). This causes the pressure to increase. Therefore, for a fixed mass of gas at a constant volume, gas pressure increases with gas prssure, and vice versa

2.2.3.2. Volume Increases as Temperature Increases

2.2.3.2.1. A fixed mass of gas at a constant volume, when temperature increases, its molecules will move faster and hit the walls more frequesntly and with greater force.For pressure to remain constant, we have to reduce the number of collisions per unit time ith the container. This can be done by increasing the volume of the container. Therefore, the volume of a fixed mass of gas at constant pressure increases wth tempertaure, and vise versa

2.2.3.3. Pressure Increases As Volume Decreases

2.2.3.3.1. For a fixed mass of gas at constant temperature, the average speed of the molecules remain the same. If the volume of the container is halfed, the number of gas molecules per unit area will be doubled. The number of molecules hitting the wall in one second will also be doubled. Consequestly the pressure will be doubled. Therefore, for a fixed mass of gas at constant temperature, gas pressure increases when volume decreases

## 3. How Energy Affecting These States Is Transferred

### 3.1. Conduction

3.1.1. Process by which thermal energy is transmitted through a medium from 1 particle to another

3.1.1.1. Explicitly Explained

3.1.1.1.1. - Thermal Energy is transferred from 1 particle to the next - Some molecules are heated - They vibrate faster as they gain energy - Collide with less energetic neighbors - Neighbors also gain kinetic energy - Energy is transferred by vibrating molecules - Continues Until Temperature Is Homogenous - No Net Movement of Molecules during this process

3.1.1.2. Factors Affecting It

3.1.1.2.1. Solids > Liquids or Gases - Molecules close together in solids - Kinetic Energy pass faster Metals > Other Solids - Metals conduct with molecules and free Electrons - Heated Electrons Move in spaces in between molecules - Same concept as molecules - Faster Rate Of Conduction

### 3.2. Convection

3.2.1. Process by which Thermal Energy is transmitted from one place by the movement of heated particles of a gas or liquid

3.2.1.1. Explicitly Detailed

3.2.1.1.1. Liquids - Convection Current - Affect of heat at the bottom of liquid - Heated liquid expands - Floats Upwards - Cold, denser liquid moves down to replace it - This is heated up - The molecule - Cycle repeats Gases - Gases > Liquids Expand more when heated

### 3.3. Raidation

3.3.1. Transfer of Thermal Energy by electromagnetic waves

3.3.1.1. Explicitly Detailed

3.3.1.1.1. - Transfers in wave form (Pure Energy) - Transforms into thermal energy of the receiving body - Travels at the speed of light - Hotter Object, Radiation > - No need to be in contact with body for heat transfer - In direction of body

3.3.1.2. Factors Affecting it

3.3.1.2.1. Surface Temperature - High > Low Colorur and Surface temperature - Darker Surfaces > Lighter Surfaces Surface Area - Large > Small

## 4. How Its Thermal Energy Is Measured

### 4.1. Definition

4.1.1. Temperature

4.1.1.1. The measure of the degree of hotness of a body

### 4.2. Instruments used to measure

4.2.1. Factors of measurement to consider

4.2.1.1. - Range of temperature to be meansured - Accuracy required - Physical conditions in which the instrument will be used

4.2.2. Types of measurement insturments

4.2.2.1. How to decide

4.2.2.1.1. Choose in instrument which - Gives different readings - When the physical properties of desired measuring of an object changes

4.2.2.2. Mercury / Alcohol in glass thermemeter

4.2.2.2.1. Physical Property it measures

4.2.2.2.2. The making of one

4.2.2.3. Resistance thermometer

4.2.2.3.1. Physical Property it measures

4.2.2.4. Thermocouple

4.2.2.4.1. Physical Property it measures

4.2.2.4.2. What it is

4.2.2.4.3. Advanteges of this

4.2.2.4.4. How to measure

4.2.2.5. Constant volume gas thermometer

4.2.2.5.1. Physical Property it measures

## 5. What Happens During Transfer Of Thermal Energy

### 5.1. Components Of Energy In An Object

5.1.1. Internal Energy

5.1.1.1. Temperature of the total kinetic energy (due to motion as in temperature fluctuation) and potential energy (due to intermolocular forces as in melting, boiling etc.) of the molecules in the body

### 5.2. How to Measure it

5.2.1. Heat Capacity

5.2.1.1. C : The amount of thermal energy required to raise the temperaure of the body by 1k or 1 degree C. SI Unit - J K^-1 [Per kelvin change] C = Q / x Q = Thermal Energy Absorbed x = change in temperature

5.2.2. Specific Heat Capacity

5.2.2.1. C : [Specific to material and per unit mass] The amount of thermal energy required to raise the temperature of a unit mass of the material by 1k or 1 degree C C = Q/mx Q = Thermal Energy Absorbed x= Change in temperature m = Unit mass SI Unit : J kg^-1 [per unit mass] K^-1 [per unit tempreature change]

5.2.3. How to calculate watts to joules

5.2.3.1. Joules = watts {joules per sec] x time [seconds]

5.2.4. Heating / Cooling Curve

5.2.4.1. Temperature Fluctuation of substance

5.2.4.1.1. x = Time y = Temperature Constant = processess taking place

5.2.5. Latent Heat Of Fusion

5.2.5.1. Energy needed to change a substance from solid to liquid without a change in temperature

5.2.5.1.1. Solid changes to liquid - Liquid molecules wider range of movement than solid molecules - Potential Energy > - Additional Energy required = latent Heat Of Fusion

5.2.6. Latent Heat Of Vaporisation

5.2.6.1. Energy needed to change a substance from liquid to gas without a change in temperature

5.2.6.1.1. Liquid Change to gas - Energy to overcome forces between molecules - Vapour to expand against atmospheric pressure - Energy required = Latent Heat of Vapourisation

### 5.3. General Ruling

5.3.1. Any substance that has low heat capacity will be a bad conductor and vise versa for high heat capacity Longer time to 'fill up' and 'diminish' heat capacity qouta

### 5.4. Processes that occur

5.4.1. Melting

5.4.1.1. Process whereby energy supplied changes the state of a substance from a solid to a liquid state, without a change in temperature. Temperature where this occurs = Melting point Same as freezing point

5.4.2. Freezing

5.4.2.1. Process whereby energy supplied changes the state of a substance from a liquid to a solid state, without a change in temperature. Temperature where this occurs = Freezing point Same as melting point - Usually said for substances that solidify at cold temperatures [Normal things say solidify]

5.4.3. Boiling

5.4.3.1. Process whereby energy suplie changes the state of a substance from liquid to gaseous stare without a change in temperature Temperature where this occurs = Boiling Point Pure Substances boiling at a definite temperature SAme temperature as condensation point

5.4.4. Condensation

5.4.4.1. Process whereby energy suplie changes the state of a substance from gaseous to liquid state without a change in temperature Temperature where this occurs = Condensation Point Pure Substances boiling at a definite temperature SAme temperature as boiling point

5.4.5. Evaporation

5.4.5.1. Occurs at ALL temperatures Takes place only on exposed surface [Boiling is throughout liquid] of liquid No bubbles formed during evaporation, unlike boiling Slow process Substance thats evaporates quickly = volatile

5.4.5.2. Factors Affecting Rate

5.4.5.2.1. Temperature of Substance at first

5.4.5.2.2. Area of exposed surface

5.4.5.2.3. Humidity

5.4.5.2.4. Motion of air

5.4.5.2.5. Pressure

5.4.5.2.6. Nature of Liquid

5.4.5.3. Relation to Kinetic Theory

5.4.5.3.1. Molecules at exposed surface layers - Diff speeds than the rest - Average speed of molecles iinc, with temp. - Get collided with first by external molecules - Break bonds at move faster - Leave liquid - Slower molecules behind - Low total kinetic energy, low average speed of molecules - lower temperature