# Matter in our surrounding

Everything is made up of some material ,that material is scientifically known as MATTER . Matter is made up of small particles . These particles attract each other but the force by which they are attracting each other vary  from state to state like  particles of solid state has  more force of attraction than particles of liquid .

# STATE OF MATTER

matter is found in three states in our surrounding SOLID, LIQUID, GASEOUS

## THE SOLID STATE

This matter state have definite shape , fixed boundaries and volume and these are uncompressible .

In solids particles are tightly packed (very closely attached to each other) they are not allowed to move freely . this packed structure give solid its properties of being uncompressible and rigid(not changing its shape and volume).

EXAMPLE :   A  block of wood has a definite shape ,it has fixed boundaries ,and cannot be compressed . Some other examples of solid state is leafs , pencil,notebook etc.

## THE LIQUID STATE

This state of matter is has a definite volume but do not have any fixed shape( ie. it takes the shape of the container in which it is poured ) they are not rigid and are also known as FLUIDS.  Liquid state gets its properties because its particles can move freely and has more space between them ass compared to the particles of solid state.

EXAMPLE:  water is an example of liquid state it does not have any fixed shape it change its shape according to the container in which it is poured but it never changes its volume / quantity . it has a tendency to flow . other examples of liquids are cough syrups, juices, etc.

## THE GASEOUS STATE

This state of matter have freely moving particles in it and does not have a fixed shape ,size, and volume .it is highly compressible and less dense .its particles  move in high speed and in a random motion.

Example: air we breathe , aroma of food.

## What Happen To The State When Temperature Is Increased :

1. When temperature  of solids is increased kinetic energy is also increased .this increase in energy result in rapid movement in the solid particle and the particle overcome the force of attraction between them and leaves their fixed space and start moving freely ( this is how solid get converted to liquid). whenever a solid get converted to liquid this process is known as FUSION.                                                                     EXAMPLE : ice (solid)  get converted to  liquid when left in room temperature (room temperature is higher than the temperature in which ice exist).                                                                                                                                                                                                                                                     {LATENT HEAT OF FUSION: the amount of heat energy required to change 1kg of solid into liquid at atmospheric pressure at its melting point }
2. When we supply heat to water ( liquid state) water particle also start moving faster ,at a certain temperature the particle of water also overcome the force of attraction between them and liquid  get converted into gas . The phenomenon of conversion of liquid into gaseous form is known as  VAPORISATION .                                                                                                                                                                             {BOILING POINT: the temperature at which liquid start boiling at the atmospheric pressure }

SUBLIMATION : The phenomenon of conversion of  a solid  directly to gaseous form (or vice versa).

• The liquid will change to solid state and gas will change to liquid when temperature is decreased.

## WHAT HAPPEN TO THE STATE WHEN PRESSURE IS INCREASED:

1. When pressure is applied ( pressure increased) to the gaseous form of matter it get converted to liquid .                                                  EXAMPLE: cng and lpg cylinders – gas is filled in them under high pressure ,they are present in those cylinders in the form of liquids.
2. When pressure is applied to the liquid form of matter it get converted to solid.                                                                                                    EXAMPLE: dry ice -it is mainly solid carbon dioxide which is stored in high pressure and get converted into gaseous form when pressure is decreased.
• Increase or decrease in temperature and pressure can change the state of matter .

# EVAPORATION:

The process of conversion of liquid into vapor state .

## FACTOR AFFECTING EVAPORATION:

1. Rate of evaporation increase with the increase in surface area : that is why evaporation is known as surface phenomenon .EXAMPLE: we spread the wet cloths when we want them to dry that is an increase in surface area and an increase in rate of evaporation.
2. Rate of evaporation increase with the increase in temperature:  EXAMPLE : it is hard to dry wet cloths in winters than in summers  because of low temperature in winter season  which decrease the rate of evaporation
3. Rate of evaporation decrease with an increase in humidity:  humidity is the amount of water present in  air if that amount increase  then the rate of evaporation decrease .
4. Rate of evaporation increase with an increase in wind speed:  cloths dry early on a windy day because wind take away the water or moisture present  on/in cloths.

### Applications Of Evaporation:

1. Water in the earthen pot  cools in summer , the  water seeps through the pores in the pot and evaporates. The latent heat required for evaporation is taken from water itself which therefore cools below the room temperature.
2. Wet cloths or cotton cloths make us feel cool in summer because the water or the sweat which cotton cloth absorb when evaporates take the necessary  latent heat from the body, lowering the body temperature and making us feel cool.
3. Our body maintain its normal temperature in hot summer days by perspiring. When the sweat evaporates it takes the necessary latent heat from the body surface, which lowers down our body temperature in hot summer days.

# SOME IMPORTANT QUESTIONS :

1 Sponge , rubber, and salt and sugar also change their state from which state of matter do they belong to?

• Sponge change its shape due to the presence of small air pockets in it nut it does not change its defined boundary.
• Rubber also change its shape but only when any force is applied on it when the force is removed it comes back to its original shape.
• Salt and sugar as whole acquire the shape of the container in which they were poured but individually ( when a single grain is observed) they remain in there fixed shape only.

So , all the above things are above material belongs to the solid state.

2 How can evaporation cause cooling ?

Whenever a liquid get evaporated its particle absorb energy from the surrounding to regain the energy lost during evaporation ,this absorption cause cooling because it takes of heat from the surrounding .

3 Why should we wear light color cotton cloths in summers ?

Light color absorb less heat . we sweat  more in summer due to our body mechanism cotton being a good absorber  absorb that sweat and help it to evaporate helping us to keep our body cool during summers.

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