UD1: MATTER_2ºESO

UNIT 2 2º ESO

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properties of MATTER

5- Gas laws

1- Properties of matter

2- Density

3-States of aggregation

4- The kinetic theory of matter

INDEX

PROPERTIES OF MATTER

01

Matter is everything that has mass, and occupies a space, i.e. a volume. Matter is characterised by its properties:

What is matter?

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They make it possible to differentiate one type of matter from another. For example, density, change of state temperatures, electrical conductivity or thermal conductivity.

They allow us to distinguish what is matter from what is not, but they do not allow us to differentiate one material from another. The most important are mass and volume.

Specific properties

General properties

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Properties of matter

vs

Volume is the space occupied by a body or a material system. The unit of volume in the International System is the cubic metre, although the litre and the cubic centimetre are often used. Flasks, graduated cylinders and burettes are used to measure volumes of liquids.

Mass is the amount of matter in a body or material system. It is a fundamental quantity. Mass is measured with a scale and its unit in the International System is the kilogram..

General properties

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Difference between mass and weight.

Formulas for calculating volume of regular solids

IRREGULAR SOLIDS

REGULAR solids

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Measurement of volume

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Archimedes' principle

density

02

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Specific properties: density.

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Density is the ratio of the mass of a body to the volume it occupies.In the above expression, m is the mass, which in SI units is measured in kg, and V is the volume, expressed in m3, so d will then be the density expressed in kg/m3, which is the SI unit for this quantity. It is a derived quantity that allows us to differentiate between substances.

Specific properties: density

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We evaluate: mass, volume and density.

Different types of densiometers

We divide volume by mass

We calculate the volume

We calculate the mass

DENSITY: it is the mass of a body per unit of volume

indirect MEASUREment

DIRECT MEASUREMENT

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Measurement of density

PROPERTIES

MATTER AND ITS

states of aggregation

03

States of aggregation

The states of matter are the various forms of matter in the universe. They are also known as states of aggregation of matter, since particles aggregate or group together in different ways in each state. Four fundamental states of matter can be considered to exist, taking into account those forms of aggregation that occur under natural conditions.

Gas

Liquid

Solid

WHAT ARE THE STATES OF MATTER?

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The atoms of solid matter are close together, so they have a fixed shape and volume. Solids cannot be compressed; however, high temperatures increase the vibration of their particles, causing them to expand slightly. Solids have shape memory, so if they are deformed, they tend to return to their original shape.

SOLIDS

They have a fixed volume, but their atoms are less cohesive than those of solids, so their shape is variable; consequently, they assume the shape of the surface or container in which they are found.

LIQUIDS

Their particles are not cohesive, and tend to disperse, so they have no fixed shape or volume. Like liquids, their shape will depend on the container, but unlike liquids, gases occupy absolutely all the available space in the container. The volume of gases changes with temperature and pressure conditions, so they can be compressed to accommodate more of them in smaller containers.

GAS

• TEMPERATURE INCREASE (PROGRESSIVE CHANGE)
• TEMPERATURE DECREASE (REGRESSIVE CHANGE)

A change of state is a physical change in a matter. They are reversible changes, the change occurs at constant temperature so this is a characteristic property and do not involve any changes in the chemical makeup of the matter.

CHANGES OF STATE

CHANGES OF STATE

the kinetic theory of matter

04

The kinetic theory of matter

To explain how matter is organised into three states, how matter behaves in each state, and how transformation between states is possible, the Kinetic Theory of Matter has been developed.

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POSTULATES OF KINETIC THEORY

• First postulate: Matter is discontinuous. Matter, whatever its state, is made up of tiny particles. These particles are characteristic of every substance, regardless of its state of aggregation.

• Second postulate: These particles are in continuous motion. This motion is different in each state (freer in gases and only vibration in solids). The particles move randomly in all directions, the faster the higher the temperature.

• Third postulate: The particles that make up matter attract each other. These forces will be strongest in solids, while in gases they will be practically non-existent.

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• The attractive forces are almost zero.
• The particles are far apart from each other and move at high speed.
• It is the most disordered state.

• The forces between particles are weaker than in the solid.
• Particles move relative to each other.
• State more disordered than in the solid.

GAS

LIQUID

• Forces between particles are very strong.
• This does not allow them to leave their fixed positions, they can only vibrate slightly.
• Ordered structures.

SOLID

THE STATES OF AGGREGATION ACCORDING TO THE CTM

CHARACTERISTICS of THE matter

Viscosity

It is the resistance to the movement of fluids. Therefore, the more viscous a substance is, the more difficult it is for it to flow.

Compression

Compression is the ability to decrease in volume under the action of a force. Therefore, solids are not compressible, liquids are barely compressible and gases are very compressible.

Diffusion

It is a phenomenon that occurs when one substance can intermingle with another. Gases diffuse very quickly, liquids more slowly, and in solids there is almost no diffusion.

Flow

Ability to move from one place to another progressively. Matter in a gaseous or liquid state is also called fluid matter.

CHARACTERISTICS OF AGGREGATE STATES

Temperature is a fundamental quantity that measures the average kinetic energy of the particles in a system. This energy is higher the faster the particles move. According to TCM, when the temperature of a system increases, so does the kinetic energy of its constituent particles. Its SI unit is the Kelvin, K. But there are other scales of measurement such as the Celsius or Fahrenheit scale.

TEMPERATURE

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Its SI unit is the pascal, Pa, in honour of Blaise Pascal. Pressure is measured with an apparatus called a manometer.

Pressure is a derived quantity that is defined as the force exerted on a unit of surface area. In the case of the pressure of a gas, it is the force exerted by the particles that make up the gas as they collide on the surface. And why do they exert a certain force on the walls of the container? According to TCM, it is because the gas particles, in their continuous motion, collide with each other and with the walls of the container. The higher the pressure, the greater their movement and the greater the number of collisions between the particles and with the walls of the container.

PRESSURE

A change of state is the physical change of a material system from one state of aggregation to another. A change of state does not change the nature of the particles that make up the material system. Whatever the change of state, it is satisfied that: - T is a fixed value: it is a specific property - They are reversible: it can return to the original state. - In the process THE TEMPERATURE DOESN´T VARY

CHANGES OF STATE

CHANGES OF STATE

Melting and boiling temperatures are characteristic of each substance, so they are specific properties, which allow us to differentiate one substance from another.

Each progressive change corresponds to a regressive one. The temperature at which each pair of changes of state occurs, for a given pressure, is identical and characteristic of each substance.

• The melting temperature (Tf) is the temperature at which melting and solidification occur.
• The boiling temperature (Te) is the temperature at which the change of state of vaporisation occurs throughout the mass of the liquid, boiling. At this temperature, condensation from gas to liquid occurs simultaneously.

CHANGE OF STATE TEMPERATURES

Solidification

Melting

MELTING AND SOLIDIFICATION

Condensation

Vaporisation

VAPORISATION AND CONDENSATION

Reverse sublimation

Sublimation

SUBLIMATION AND REVERSE SUBLIMATION

• Cooling graph: if we now start from a vapour and cool down, i.e. remove energy, we will cause regressive changes and a decrease in temperature.

To study changes of state experimentally, we have to make precise measurements of the temperature of the matter we are heating or cooling in order for the change of state to occur for the entire duration of the process. - Heating graph: when we heat a system, we are supplying it with thermal energy that makes the particles move at a higher speed. This can lead to a progressive change of state, if the temperature reaches the melting or boiling temperature.

CHANGES OF STATE GRAPHS

Heating and cooling curves show how temperature changes when a substance is heated up or cooled down. The curves are flat when the substance changes state, like melting, boiling, freezing or condensing.

What are heating and cooling curves?

Heating and cooling curves

1. When a solid is heated, the particles gain energy and vibrate more. The temperature rises as heat is added.
2. At the melting point, energy goes into breaking bonds between particles, turning the solid to liquid.
3. The temperature stays the same during melting, giving a flat line on the graph.
4. The same happens when a liquid is heated to boiling point. Energy is used to break the bonds completely, forming a gas.
5. The temperature stays steady during boiling, giving another flat line.

Heating curves

Heating and cooling curves

1. When a gas is cooled, particles slow down and lose energy. The temperature drops as heat is given off.
2. At the condensation point, particles come together and bond turning the gas into a liquid. The energy released stops the temperature dropping further.
3. The temperature stays the same during condensation giving a flat line on the graph.
4. The same happens a when liquid is cooled to freezing point. Particles arrange into solid structure, releasing heat energy.
5. This stops temperature dropping as liquid becomes solid, giving another flat line

Cooling curves

Heating and cooling curves

gas laws

05

Gas Laws

• For the study of these laws, we will consider that gases behave in an ideal way, that is to say, that the particles that make up the gas occupy a negligible volume compared to the volume of the container that contains it, with the forces of attraction between them being zero.

• To observe how one of these three quantities (dependent quantity) varies, another (controlled quantity) is held constant and the third (independent quantity) is varied.

• The ideal gas laws show the relationship between the pressure, volume and temperature of a gas.

GAS LAWS

GAS LAWS

We increase the temperature

Pressure increases

Pressure increases

We decrease the volume

When a gas undergoes transformations at constant pressure, as the temperature increases, the volume also increases, and vice versa.

When a gas undergoes transformations at constant volume, as the temperature increases, the pressure also increases, and vice versa..

CHARLES´ LAW

GAY-LUSSAC´S LAW

When a gas undergoes transformations at constant temperature, as the volume of the container decreases, the pressure increases, and vice versa.

BOYLE -MARIOTTE´S LAW

GAS LAWS

CHARLES´ LAW

GAY-LUSSAC´S LAW

BOYLE-MARIOTTE´S LAW

GAS LAWS

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Con las plantillas de Genially podrás incluir recursos visuales para dejar a tu audiencia con la boca abierta. También destacar alguna frase o dato concreto que se quede grabado a fuego en la memoria de tu público e incluso embeber contenido externo que sorprenda: vídeos, fotos, audios... ¡Lo que tú quieras!