Matter In Our Surroundings

Anything which occupies space and has mass is called matter.

There are three states of matter:- solid, liquid, gas.

Chair, almonds: solid since they have definite shape and mass.

Cold drink: liquid since it has fixed volume.

Air, Smell of the perfume, smell: gas matter since they are gases.

The smell is a state of the matter since it is due to the presence of some vapour state substance in air which occupy space & have mass due to which there is smell.

Hence, Chair, Almonds, Cold drink, smell, the smell of perfume and Air are examples of the matter.

The smell of hot sizzling food reaches you several meters away but to get the smell from cold food due to very high rate of diffusion of hot aroma particles of the food in the air as compared to the particles of cold food, due to the high speed of particles and large space between them, gases show the property of diffusing very fast into other gases at high temperature as compare to low temperature.

The diver is able to cut through water in a swimming pool because of the property of the matter have space between them.

Explanation:

Water in the swimming pool is an example of the liquid state of matter, as a result, particles in the water move freely and have greater space between each other as compared to particles in the solid state. Thus, the diver is able to cut through the water in a swimming pool.

Anything which has mass and occupies space is called matter. The important characteristics of the particles of matter(atoms or molecules) are following:

(i) The particles of matter have spaces between them known as inter molecular space. Particles of one type of matter are able to get into the spaces of the particles of other. For example, when we dissolve salt or sugar in water, the particles of sugar or salt get evenly distributed in water.

(ii) The particles of matter are constantly moving as they possess kinetic energy. With the increase in temperature, particles move faster. As a result, the kinetic energy of the particles also increases.

(iii) The particles of matter attract each other. They have force of attraction acting between them. This force helps to keep the particles of matter together. The strength of this force of attraction depends on the nature of matter.This is known as inter molecular force of attraction

Density is mainly determined by the intermolecular forces of attraction
Solids have high intermolecular forces of attraction, as a result, they have high density followed by liquids and gases which have less intermolecular forces of attraction. We can draw the following inference:-
On the basis of the above information the order of increasing densities of the given substances is:

Air (gas) < Exhaust from chimneys (condense gas)< Cotton(light porous solid) < Water (liquid) < Honey(Thich liquid) < Chalk(heavy porous solid) < Iron(solid).

The main differences in the characteristics of the three states of matter, solids, liquids and gases are given below:

• Property of the Substance to retain/maintain their shape when subjected to outside force is known as rigidity.
• This property is determined by the inter molecular force of attraction.

• The particles of matter have intermolecular spaces. If an external force is applied, it can bring these particles closer.
• The property of a fluid or a solid due to which its volume decreases when pressure is applied is called Compressibility.
• Gases have high compressibility because they have a lot of inter molecular spaces.
• The particles in solids and liquids are closely packed, so solids and liquids do not have much compressibility.

• The tendency of the particles to flow is known as its fluidity.
• Gases and liquids exhibit the property of fluidity, so they are called fluids.
• This property is determined by intermolecular force of attraction as well as intermolecular spaces.
• Due to large intermolecular spaces and very weak forces of attraction, gases can flow very easily followed by liquids and then solids which have almost negligible fluidity.

• A gas is able to fill the container because its particles are able to vibrate randomly in all the directions.
• The particles of gas have very high kinetic energy and almost negligible forces of attraction.
• As a result, gases are able to fill the container fully.

• The external form or appearance of a substance is called its Shape.
• The particles in a solid have very strong forces of attraction due to which they are closely packed so they have a fixed shape.
• The liquids and gases have comparatively weaker forces of attraction between them as a result they take the shape of container in which they are stored.

• The energy possessed by particles due to their motion is called kinetic energy.
• At a given temperature, the particles of gas have the maximum kinetic energy.
• Liquids have lesser kinetic energy as compared to gases whereas solids have the least kinetic energy at a given temperature.

• The mass per unit volume of a material is called its density.
• Solids have high densities because of strong forces of attraction.
• Liquids usually have lower densities than solids because their particles are loosely packed as compared to solids.
• Gases have the lowest densities because their particles are very far away from one another due to weakest forces of attraction among them.

(a) A gas is able to fill the container because its particles are able to vibrate randomly in all the directions due to high kinetic energy as result they fill up the vessel completely in which they are kept.

(b) The particles of a gas have very high kinetic energy. They move randomly with high speeds in all directions. Due to this random movement, the particles hit each other and also the walls of the container. As a result, a gas exerts pressure on the walls of the container.

(d) We can easily move our hand in air but not do the same through a solid block of wood because of the differences in the intermolecular forces of attraction.Air has very low intermolecular force of attraction as result even small amount of force can separate air particles whereas in case of solids the intermolecular force of attraction are very strong and large amount of force is required to break them.This is the reason we can easily move our hand in air but t do the same through a solid block of wood we need a karate expert

(a) Kelvin is the SI unit of temperature. To change a temperature on the Kelvin scale to the Celsius scale you have to subtract 273 from the given temperature, and to convert a temperature on the Celsius scale to the Kelvin scale you have to add 273 to the given temperature.

Temp. on Kelvin scale = Temp. on Celsius scale + 273

300 K = Temp. on Celsius scale + 273

Temp. on Celsius scale=300 - 273 = 27⁰C

Thus, a temperature of 300 K on Kelvin scale is equal to 27⁰C on Celsius scale.

(b) Kelvin is the SI unit of temperature. To change a temperature on the Kelvin scale to the Celsius scale you have to subtract 273 from the given temperature, and to convert a temperature on the Celsius scale to the Kelvin scale you have to add 273 to the given temperature.

Temp. on Kelvin scale = Temp. on Celsius scale + 273

573 = Temp. on Celsius scale + 273

And, Temp. on Celsius scale= 573 - 273 = 300°C

Thus, a temperature of 573 K on Kelvin scale is equal to 300°C on Celsius scale.

(a) Water will be in gaseous state at 250°C. The boiling point of water is 100°C. Heating the water above this temperature will change it into gaseous state.

(b) The boiling point of water is 100°C. At this temperature the liquid starts changing into gas. Boiling is a bulk phenomenon. Particles from the bulk of the liquid gain enough energy to change into the vapour state. Hence, the physical state of water at 100°C will be both ‘liquid’ and ‘gaseous’ state.

Atmospheric gases can be liquefied by applying pressure and reducing the temperature.When pressure is applied on a gas at a reduced temperature, its molecules get closer and they start attracting one another to form a liquid. When a gas is compressed by applying high pressure, a lot of heat is produced. So, while applying high pressure, it is necessary to keep the temperature low which helps to take away the heat released during compression.

The outer walls of the cooler are constantly sprinkled by water. This water evaporates at a faster rate during the hot dry weather causing a cooling effect in the inside air of the cooler which is sent in the room through a fan.On a hot dry day, humidity is very low so the cooler works efficiently

Earthen pot is porous with a lot of pores on it. The water oozes out of these pores constantly. This water then gets evaporated through the pores quickly. Since, some heat energy is taken from the water during the process of evaporation. This process makes the pot cold which further cools down the water inside the pot.

Acetone, petrol and perfume are volatile liquids. They change into vapours easily when they come in contact with the air. In order to change from the liquid to the vapour state, acetone, petrol or perfume requires latent heat of vaporisation. These liquids absorb this latent heat of vaporisation from our palm. As a result, heat energy is lost from the palm and it feels cold.

When hot tea or milk is taken in a saucer, its surface area is increased. Since, evaporation is a surface phenomenon. The rate of evaporation becomes faster with the increase in surface area. Tea or milk cools down faster in a saucer making it easier for a sip. On the other hand, when hot tea or milk is taken in a cup, surface area is comparatively small due to the narrow shape of the cup. Small surface area slows down the process of evaporation. Hence, tea or milk takes long time to cool in a cup which makes it difficult to take a sip.

• Light colour is preferred because it reflects heat. Because of our body mechanism we tend to perspire more during summers. This helps to keep our body cool. During evaporation, the particles at the surface of the liquid gain energy from the surroundings or body surface and change into vapour.
• The heat energy equal to the latent heat of vaporization is absorbed from the body leaving the body cool.
• Cotton, being a good absorber of water helps in absorbing the sweat and exposing it to the atmosphere and makes evaporation easy.

(a) Kelvin is the SI unit of temperature. The Relation between Kelvin and Celsius is as follow:-

Temp. on Kelvin scale= Temp. on Celsius scale + 273

According to Question:-

Therefore, 293 K is equal to 20°C.

(b) Kelvin is the SI unit of temperature. The Relation between Kelvin and Celsius is as follow:-

470k = Temp. On Celsius scale + 273

Therefore, 470 K is equal to 197^oC.

(a) Kelvin is the SI unit of temperature.

Temp. on Kelvin scale = Temp. on Celsius scale + 273

Temp. on Kelvin scale= 25^oC + 273 = 298 K

Therefore, 25°C = 298 K

(b) Kelvin is the SI unit of temperature.

Temp. on Kelvin scale= Temp. on Celsius scale + 273 = 373⁰C + 273 = 646 K

Therefore, 373°C = 646 K

(a) Naphthalene is a volatile organic compound which can undergo sublimation. It directly changes into vapour state without leaving any solid. The naphthalene balls sublimate completely forming naphthalene vapours and hence, they disappear without leaving any solid residue.

(b) Perfume contains a volatile solvent which diffuses into the air. When liquid perfume is applied, it quickly changes into vapours. As a result of diffusion, the perfume vapours move very rapidly in all directions in air, mix up with air particles and spread in the air. When this air containing perfume vapours reaches several meters away, we can smell the perfume.

The forces of attraction between the particles of a gas is minimum, intermediate in case of a liquid and are maximum in a solid.On the basis of this information we can arrange the following substances in increasing order of forces of attraction which is as follow:-

oxygen < water < sugar

*For Extra Information
(i) Oxygen is a gas, the forces of attraction between its particles will be the weakest.

(ii) Water is a liquid. The forces of attraction between its particles will be stronger than that of oxygen but will be weaker than that of sugar.

(iii) Sugar is a solid. The forces of attraction between its particles will be the strongest.

(a) Between 0⁰C and 100⁰C water exists as a liquid. The physical state of water at 25°C is liquid.

(b) 0°C is the melting point of ice as well as the freezing point of water. Hence, the physical state of water can be both liquid and solid at 0°C.

(c) 100⁰C is the boiling point of water as well as the condensation temperature of steam. Hence, the physical state of water can be both liquid or gas at 100⁰C.

(a) The freezing point of water is 0⁰C and the boiling point of water is 100⁰C. At room temperature the particles of water do not have enough energy to break free from the inter-molecular force of attraction of each . Hence, water remains as a liquid at room temperature.

(b) An iron almirah is solid at room temperature because melting point of iron i.e the temperature required to convert solid iron to liquid iron is much higher than the room temperature

273 K or 0°C is the melting point of ice.Now, ice at 273 K is more effective in cooling a substance than water at the same temperature because in order to overcome the fusion to become water, ice at 273 K will absorb heat energy from the surroundings known as latent heat of fusion. Hence, the cooling effect of ice will be more than water at the same temperature because water does not absorb this extra heat from the medium.
The latent heat of melting of ice is 334 Joules per kilogram

Particles in steam, that is, water vapour at 373 K (100°C) have more energy than water at the same temperature. This is because particles in steam have absorbed extra energy in the form of latent heat of vaporisation. When steam tends to cool down, first steam condenses to water on skin and then water tends to cool down to the temperature of the skin. Since steam gives out much more heat than boiling water, it causes more severe burns.

(i) In process A, a solid is changing into a liquid. Hence, A is melting or fusion.

The temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.

(iii) In process C, a gas is changing into a liquid. C is condensation.

(iv) In process D, a liquid is changing into a solid. D is solidification.

(v) In process E, a solid is directly changing into a gas. E is sublimation which is done under increased heat and decreased pressure.

(vi) In process F, a gas is changing directly into a solid. F is also sublimation which is done under decreased heat and increased pressure.

The process of change of state of solid directly into a gas without changing into liquid state (or vice versa) is called sublimation.