1 Matter in our surrounding
Anything which occupies space and has mass is called matter. Air and water; hydrogen and oxygen; sugar and sand; silver and steel; copper and coal; iron and wood; ice and alcohol; milk and oil; kerosene and petrol; carbon dioxide and steam; carbon and sulphur; rocks and minerals are all different kinds of matter, because can all of them occupy space and mass.
If we look around us, we can see a large number of things of different shapes,size and textures.Many of these things are used by us in our everything life.For example, we eat food, drink water,breathe in air and wear clothes.We use table and chairs for studying and bed for sleeping.We also see other human beings, various animals,plants,and trees around us.The things like food,water,air, clothes, table,chair,human beings,animals, plants and trees etc.are all examples of matter.
The only conditions for something to be matter are that it should occupy space and have mass. Now, the things like friendship, love, affection,hatred, good manners,thoughts, ideas,taste,smell etc.,do not occupy space and don't have mass.So, from the view of chemistry,things like friendship, love, affection, hatred, good manners, thoughts, ideas,taste and smell are not considered matter.
Matter can be classified in a number of ways.Ancient Indian philospher said that all the matter,living or non-living,was made up five elements: air,earth,fire, sky and water. Modern day scientist classify matter in two ways:on the basis of its physical properties and on the basis of its chemical proporties.On the basis of physical properties ,matter is classified as solids, liquids and gases.And on the basis of chemical properties,matter classified as elements, compounds and mixture.
Matter is made up of particles
Everything around us is made of tiny pieces or particles.Our body is made of particles,our tables is made up of particles and the book is also made of matter.The number of particles in everything is however very, very lrge.For example a small rain drop contains about 10^21 particles of water in it!The particles which makeup matter are so small that we cannot see them,with high powerful microscope.
Browian motion
It was Robert Brown who discovered in 1827. He looked through his microscope at pollen grain suspended in water in this way the browian motion discovered.It is an unintentional discovery.
Chacteristics of particles of matter
The important chacteristics of particles of matter are :
1. The particles of matter are very, very small.
2.The particles of matter have spaces between them.
3.The particles of matter attract each other.
4.The particles of matter are constantly moving.
Classification of matter as solids, liquids and gases.
One the basis of matter can be classified into three groups: solids, liquids and gases.For example:
1. Sugar,sand, iron, wood,rocks, minerals. are solids.
2. Water,milk,oil, kerosene, petrol and alcohol are liquids.
3.Air, oxygen, hydrogen, carbon dioxide and steam are gases.
Properties of solids
1.Solid have a fixed shape and a fixed volume.
2. Solids cannot be compressed much.
3.Solids have high densities.They are heavy.
4.Solids don't fill their container completely.
5.Solids don't flow.
Properties of liquids
1.Liquids have a fixed volume but they have no fixed shape.
2.Liquis can negligibly compressed.
3.Liquids have moderate high densities.
4.Liquids don't fill their container completely.
5.Liquids generally flow easily.
Properties of gases
1.Gases have neither a fixed shape nor a fixed volume.
2.Gases can be compressed easily.
3.Gases have very low densities.
4.Gases fill the container completely.
5.Gases flow easily.
Diffusion
The spreading out and mixing of a substance with another substance due to motion of its particles is called diffusion.
Changes of state of matter
Matter can exist in three physical state solid liquid gases. For example water exist as a solid in the form of ice is a liquid in the form of water and as in the gas in the form of steam water comes out of the freezer or a refrigerator as water out of the tab and as team out of the capital of boiling water.
We change the physical state of matter in two ways:
1. By changing the temperature and
2. By changing the pressure
When we say that we can change the state of matter by changing the temperature, we mean that the state of matter can be changed by heating or by cooling it. and when we say that we can change the state of matter by changing the pressure mean that the state of matter can be changed by increasing pressure on it or by decreasing pressure on it.
The spaces between the particles on mother force of attraction between the particles and the amount of moment A particle can be changed by changing pressure and temperature of a substance. so combat depending on the pressure and temperature are exactly the same substance can exist in all the three physical States solid liquid and gas. for example under normal pressure water exist as a solid the form of ice at a temperature of zero degree Celsius or below. it exist as a liquid in the form of water at room temperaturecomma and guess and as a gas in the form of steam at a temperature of hundred degree Celsius or above. from this discussion we conclude that the two factors which decide whether a given substance should be a solid liquid and gaseous state are temperature and pressure. We will now discuss about the effect of change of temperature and effect of change of pressure on the physical state in details one by one.
Effect of change of temperature
By increasing the temperature of a solid can be converted into a liquid state ; and the liquid can be converted into gaseous state.And by decreasing the temperature of a gas can be converted into liquid state and the liquid can be converted into solid state.
1.Solids to liquid change: Melting
If we heat ise it changes into water. in this case the solid ice changes into liquid water so a change of state has taken place. The process of which solid state changes into liquid on heating is called melting or fusion.So when ice changes into water on heating it is called melting of ice a fusion of ice. A change of state takes place during the melting.The melting of a solid substance Melting changes into liquid at atmospheric pressure is called melting point of the substance. For example the ice melts at a temperature 0 degree Celsius to form liquid water so on melting point of ice at zero degree celsius. At melting point of ice changes its States from solid to liquid.
Different solid shape different melting point.For example,the melting point of ice is zero degree celsius ,the melting point of wax is 63 degree celsius, the melting point of iron is 1535 degree Celsius.The melting point of a solid is a measure of the force of attraction between it's particles.Higher the melting point of solid substance greater will be the force of attraction between its particle.For example,the melting point of iron melt is very high which tells us the force of attraction between the particle of iron is very strong.
2.Liquids to Gas change:Boling
Water normally exist in the liquid.If we go on heating water camper it will ultimately start boiling and changes rapidly into the gas called steam.In this case coma the liquid water changes into a gas from my so as to change state has taken place. The process in which the liquid substance changes into gas rapidly on heating commonly called boiling. So,when water changes into steam rapidly and heating, it will called boiling point of water. a change of state takes place during boiling. The feeling of liquid takes place at a fixed temperature. The temperature at which the liquid boils and changes rapidly into a gas at atmospheric pressure is called the boiling point of the liquid.For example condom when water is heated to a temperature of hundred degree Celsius it was rapidly to form gas constant so the boiling point of metal is hundred degree Celsius. At boiling point of water changes its state from liquid to gas.
3. Gas to liquid Change: Condensation
If wkuhlz team by lowering its temperature it is converted into liquid water. In this case of gas changes into a liquid for change of state has taken place. The process of changing of gas to a liquid by cooling, is called condensation. So come when steam changes into water on on pulling it is called condensation of steam. A change of state takes place during condensation.
4.Liquid to solid change: Freezing
When water is cooled,it changes into solid ice.The process of changing a liquid into solid by cooling is called freezing. For example when water is cooled it gets converted into solid called ice. This is called the freezing of water. Feezing means on edification. When water freezes to form ice then there is the change from liquid state to solid state. please note that freezing is the rivers of melting. So the freezing point of a liquid is the same as the melting point of its solid. For example, the melting point of ice is zero degree celsius so the freezing point of water is also 0 degree Celsius. A change of state of occur during freezing.
Latent heat
Normally, when heat is given to a substance that its temperature rises. This however is not so when a change of state of substance take place. Because when heat is given to the change of state of substance are there is no rise in temperature of the substance. The heat of energy which has been supplied to the change of the state of a substance is called latent heat. Latent heat does not rise the temperature.But latent heat has always to be supplied to change the state of a substance. the word that means that can't means hidden. It is called latent heat because it becomes hide in the substance undergoing the change of state and national show its presence by raising the temperature. To the latent heat which has which is given to change the state of a substance cannot be detected by a thermometer.
Latent heat is of two type:
1.Latent heat of fusion,and
2.Latent heat of vaporisation.
Sublimation
Most ab to solid substance coming when heated, first change into liquid and then into vapour. This paper on cooling first forms a liquid and then a solid.But there are a few solid substance which changes directly into vapour on heating and the vapour gives back solid substance on cooling. The changing of solid directly into vapour on heating of vapour into solid on cooling us known as sublimation Please note that:
1. the changing of solid directly into vapour is called sublimation, and
2. the changing of epidermal into solid is called sublimation.
The solid substance which undergoes sublimation is said to be subline.The solid obtained by cooling the vapour of solid is called as sublimate.Ammonium chloride undergoes sublimation.The common substance which undergoes sublimation are: ammonium chloride, iodine, camphor, naphthalene and anthracite.
Evaporation
When a liquid is left exposed to air combat volume decreases gradually. This is due to evaporation. in this process some of the liquid at the surface turns into pepper and mixes with the gas in the year. This when a liquid turns into vapour it is said to be grateful stop we cannot define evaporation as follows the process of liquid changing into vapour even below its boiling point is known as evaporation. Evaporation of a liquid can take place even at the room temperature though it is the faster at higher temperature full structure for whatever be the temperature at which the evaporation takes place on the latent heat of vaporization must be supplied to enable a liquid changes its vapour. The weight loss is died due to evaporation of water present in them.And rain water puddles also dry up because of evaporation of water. Common salt is also recovered from seawater by the process of evaporation.
Factors affecting Evaporation:
1.Temperature
2.Surface area
3.Humidity
4.Wind speed
1.Temperature
The rate of evaporation increases on increasing the temperature of the liquid.In other words the rate of evaporation of a liquid increases on heating. When the temperature of the liquid is increased by eating it more particle of the required that and kinetic energy to go into the vapour state. This increases the rate of evaporation. This is the rate of evaporation of the liquid can be increased by eating it will stop the rate of evaporation of a liquid becomes maximum boiling point.
2.Surface area of the liquid
The rate of evaporation increases on increasing the capacity of the liquid. So, if the surface area of the liquid exposed to the air is increase the rate of evaporation of the liquid increases.For example, is liquid is kept in a test tube and in a China dish then the liquid kept in the China dish will it more rapidly. in our daily life away speed of the worst way while dying to increase their surface area for the rapid evaporation of water present in them. After the way through dry quickly because the rainwater is spread over a large area of the road this gives the particle of the water or greater chance to explain escaping from the liquid. From this discussion will conclude that the rate of evaporation of liquid can be increased by the increasing surface area of the liquid.
3.Humidity of air
The amount of water vapour present in air is represented by the term called humidity. When the amount of water vapour present in the air is small compared the year appears to be dry and we say that the humidity is low. On the other hand when the amount of water vapour in the air is large, the year appears to be dump and we say the humidity is high. the humidity of air tells us the degree of the dampness of the air.
When the humidity of air is lokama than the rate of evaporation is the water vapours more readily. under these conditions , sweet from our body evaporate rapidly and we feel cool and comfortable.The weight loss is dry quickly as under the the conditions of the low humidity of air full stops when the humidity of air is higher than the rate of evaporation is low and the water evaporates very slowly full structure in the latter part of Summer the humidity of air increases. People sweet a lot in touch with the full stop but the street from our body does not operate properly due to the high humidity of air. Such way that comes mugi and we feel hot and uncomfortable. This type of weather is experienced during cloudy days in the summer season and in the area close to the sea full stop the weight clothes take longer time to dry when the humidity of air is high.
4.Wind speed
The rate of evaporation of a liquid increases with increasing wind speed. When the speed of the wind increases the particle of water vapour move away with the decreasing the amount of water vapour in the surroundings. This increases the rate of evaporation of water. The wet waste cloth dry more quickly on a windy day because the operation is faster due to the high speed of the wind.
Cooling caused by evaporation.
We have already study on liquid evaporates it must be supplied the latent heat of vaporization. The cooling caused by population is based on the fact that when a liquid evaporates it draws the latent heat of vaporization from anything which is which touches. By using heat combat this anything get School. Keeping this point in mind we will now get some examples of cooling caused by evaporation.
If we put our little spirit at the back of our hand and way with around the spirit evaporates rapidly and other hand feels very cold. This is due to the fact the to change from the liquid to the epitrate commerce spirit required latent heat of vaporization. The spirit takes the heat of vaporization from other hand. the hand losers heat and get cool. This is the example of cooling caused by evaporation.
During hot summer days, water is usually kept in the earthen pot to keep it cool. letters see how we get cool. the effort has a large number of extremely small pots in its world. Some of the water continuously keep seeing through the sports to outside of the pot this. This water evaporates continuously and takes the latent heat required for the projection from the other important the remaining waterfalls in this way combat the remaining butter losers heat and get cool. This is the example of the cooling caused by evaporation. It should be noted that all the water on the earth does not get a pretty due to high value of latent heat of vaporization of water. At many places are especially in villages, people often sprinkle water on the ground in front of their home home during the hot summer evening. This water evaporate by taking the large latent heat of vaporization from the ground and surrounding area. By using heat, the place became cool and comfortable. Please note that the water vapour rising from the lives of that we also cools the surrounding air.
Perspiration is our bodies method of maintaining a constant temperature. On a hot day or after doing some physical exercise when our body temperature 10 rise to much, with sweat glands give out moisture on a screen. When the sweet evaporates combat takes the latent heat of vaporization from our body. This keeps our body cool.
We should we wear cotton clothes inhot summer days to keep cool and comfortable. this can be explained as follows. We get a lot of sweet on a body in hot summer days will stop now, cotton is a good absorber of water so it absorbs the sweet from our body and exposes it to the air for evaporation. The preparation of this sweet girls upper body. The synthetic cloth is do not absorb much up sweat,so they fail to keep body cool in summer. Of an increases the rate of evaporation of sweat from a bit skin and makes us feel cool and comfortable.
The cooling in desert room cooler is caused by pollution of water. A desert cooler cool better on a heat and dry day because the higher temperature on a hot day increases the rate of evaporation of water and the dryness of air also increases the rate of evaporation of water. And due to increased rate of evaporation of water a desert room cooler cool better on a hot day and dry day.
It is a common observation that we are able to sip hot tea faster from a saucer rather than from a. this can be explained as follow a saucer has a large surface area .Due to large surface area of saucer the evaporation of water from the saucer's first. And this first evaporation cools the saucer more quickly making it convenient for us to drink it.
To show the presence of water vapour in air
There is always some water vapour in the air around us. The amount of water vapour in air keeps on changing. Water vapour comes into the air from the evaporation of water present in the pond lake river and ocean. Water vapour is also given out by the plant by the process of transpiration. Animals give out water vapour when they breathe out your. land is also water vapour on being governed by this. all this water vapour goes into the air around us. We will now be described the experiment to demonstrate the water vapour is present in the air.
Thepresence of water vapour in air can be shown by the following experiment.Iit take steel tumbler and put some well crushed ice into it. With that from the from outside with the piece of clean dry cloth so as to make it outer surface completely dry. Allowed the ice containing steel from tumbler to stand underdistrubed for about 5 minutes. A large number of any drops of water appear on the outer surface of steel drum. This happens as follows the year around the steel from blood contains water vapour in it. When this water vapour come in contact with cold outside surface of the steel tumbler, they condenses to tiny drops of liquid water full stops of the formation of the drop of water in the outside surface of the of it from the containing crused ice, shows the presence of water vapour in air.
Two more States of matter:Plasma and Bose Einstein condensate
Scientist now say that there are actually five States of matter: Solid, Liquid,Gas,Plasma and Bose-Einstein Condensate.
Plasma is a mixture of free electrons and ions.
