Chemistry – Materials
- The branch of Chemisry that deals with the study of all the elements and the properties , preparations and applications of their compounds are called – InOrganic Chemistry
- The branches of Chemistry that deals with all aspects of Carbon and its compounds are called – Organic Chemistry
- The Chemistry that deals with the Theoretical and Mechanical aspects of Chemical reactions are called – Physical Chemistry
- The branches of Chemistry involves the study of Chemical changes and reactions occurring with in living systems and in life process are called – Bio Chemistry
- The study of constituents and their identification in Chemical subsistence is called – Analytical Chemistry
- Analytical Chemistry can either be qualitative or quantitative in nature
Matter and Its Nature
- Every thing in this Universe is made of materials ,which scientists have named “matter they have both mass and volume”.
- Anything that occupies space and possess weight is termed matter.
- The amount of matter contained in any object is known as its Mass.
- Matter can neither be created nor be destroyed ,it can onlybe changed from one from to another.
- Early Indian Philosophers classified matter in the form of „ 5 „ basic elements that is “ Panch Tatva”.
- They are air,earth ,fire ,sky and water.
- Modern Scientists classified two types based on their physical properties and chemical nature.
- One way of classification of matter is into pure substances and mixtures.
- Another way it is classified into elements, compounds and mixtures.
Physical nature of matter
- Matter is made up of particles.
- The particles are very small and have space between them.
- The particles are continuously moving due to the kinetic energy.
- As the temperature rises, the kinetic energy of the particles also increases ,and they move faster .
- The particles of matter attract each other due to a force acting between them and keeps them together.
- The strength of the force of attraction varies from one kind of matter to another
States of matter
- The matter exist in three different states, such as solid, liquid and gas.
- The states of matter arise due to the variation in the characteristics of the particles of matter.
- The solids have a definite shape ,distinct boundaries ,fixed volumes and have neggligable compressibility.
- They were difficult to change their shape.
- The liquids have no fixed shapes but have a fixed volume.
- Liquids flow and can change shape,they are not rigid built can be called fluid.
- The solids, liquids and gases can diffuse in to liquids.
- The rate of diffusion of liquids is higher than that of solids.
- This is due to in liquid state,the particles move freely and have greater space between each others.
- The gases are highly compressible than both solids and liquids.
- The Liquified Petroleum gas (LPG) Cylinder and Oxygen supplied to hospitals in Cylender are compressed gases.
- The Compressed natural Gas (CNG) is used as fuel in vehicle due to its high compressibility.
- The Gases show the property of diffusion very fast in to other gases.
- In the gaseous state the particles move about randomly at high speed.
- The minimum temperature at which a solid melts to become a liquid at the atmospheric pressure is called its ‘melting point’ .
- The melting point of a solid is an indication of the strength of the force of attraction between its particles .
- The melting point of ice is 273.15k.
- The process of melting or change of solid state in to liquid state is called Fusion.
- Kelvin(K) is the SI unit of temperature.
- 0oC = 273.15K / 273K = 0oC
- To convert a temperature on the Kelvin scale to the Celsius scale to substract “ 273 ” from the given temperature.
- ie, K – 273 = Celsius
- To convert a temperature on the Celsius scale to the Kelvin scale to add “ 273 “ to the given temperature. – ie , C + 273 = Kelvin
- The amount of heat energy is required to change ‘1kg’ of solid in to liquid at atmosphere pressure at its melting point is known as the ‘ Latent heat of fusion’.
- The particles in water at 0oC (273K)have more energy than the particles in ice at the same temperature.
- The temperature at which a liquid starts boiling at the atmosphereic pressure is known as its ‘boiling point’. It is a bulk phenomenon.
- Particles from the bulk of the liquid gain enough energy to change into the vapour state.
- The temperature for water to change into vapour state is 373K. ie (373 – 273o)C = 100oCThe water vapour at 100oC have more energy than water at the same temperature is due to the “latent heat of vaporization”.
- That is particles in the steam have absorbed extra energy in the form of latent heat of vaporization .
- Solid state → (heat) → Liquid state → (heat) →Gaseous state.
- Solid state ← (cool) ← Liquid state ← (cool) ← Gaseous state.
- The state of matter can be changed in to another state by changing the temperature.
- A change of state directly from solid to gas without into liquid state is called “Sublimation”.
- The direct change of gas to solid with out into liquid is called ‘deposition’ .
Change of Pressure – effect
- The difference in various states of matter is due to the difference in the distance between the constituent particles.
- Applying pressure can reducing temperature and liquify gases.
- Atmosphere or ‘atm ‘ is a unit of measuring pressure exerted by a gas.
- The SI unit of pressure is pascal ‘ pa ‘.
- 1atm = 1.01 x 105 pa.
- The pressure of air is atmosphere is called atmospheric pressure.
- The atmospheric pressure at sea level is 1 atm , that is normal atmospheric pressure.
- The Solid Carbondioxide (Co2 ) is stored under high pressure due to the tendency to direct conversion of gaseous state on decrease of pressure to 1 atm.
- Hence the solid carbondioxide is called ‘ dry ice ‘.
- The pressure and temperature determine the state of a substance.
Evaporation
- The phenomenon of change of a liquid in to vapours at any temperature below its boiling point is called evaporation.
- The rate of evaporation increase with
- An increase of temperature
- An increase of surface area
- A decrease in humidity
- An increase in wind speed
- Humidity is the amount of water vapour present in air.
- If the amount of water in air is high ,the rate of evaporation decreases.
- Due to evaporation clothes dry faster on a windy day.
- Modern scientists talking of ‘ 5 ‘ states of matter such as,
- Solid
- Liquid
- Gas
- Plasma
- Bose Einstein Condensate.
- The plasma state consists of super energetic and super excited particles.
- These particles are in the form of ionised gases .
- The fluorescent tube and neon sign bulbes the gases inside the bulbes get ionised and creates a plasma glowing inside.
- The sun and the stars glow due to the presence of plasma in them .
- In ‘ 1920 ‘ Indian Physicist Satyendra Nath Bose had done some calculation for the ‘ 5‘ th state of matter.
- Based on this Albert Einstein predicted a new state of matter, that is the Bose Einstein condensate (BEC).
- In 2001 Eric. A. Cornell , Wolfang Ketterle and Carl .E. Weiman of USA received the Nobel Prize in physics for achieving “ Bose – Einstein condensation”.
- The BEC is formed by cooling a gas of extremely low density about one hundred thousandth the density the density of normal air to super low temperature.
- One way the matter is devided in to pure substances and mixtures.
- Most of the matter around us exist as mixtures of two or more pure components.
- Air – Mixture of more than 5 gases
- Petrol – Mixture of several hydrocarbons
- Drinking water – Mixture of pure water and several salts.
- Milk – Mixture of water , proteins ,vitamins ,Minerals etc
- A very few examples of the use of pure substances in daily life such as
- Copper used in electrical wiring
- Distilled water in car battaries
- A solution is a homogenous mixture of two or more substances.
- We can also have solid solutions and gaseous solutions.
- Alloys – Solid solution
- Air – Gaseous solution
- In a solution there is homogeneity at the particle level.
- The major component of a solution that dissolves the other component in it is called “ the solvent”.
- The minor component of a solution that is dissolved in the solvent is called “ the solute”.
- In sugar solution ,water is the solvent and sugar is the solute.
- Air is a Mixture of gas in gas
- The main constituents of air are,
- Nitrogen – 78%
- Oxygen – 21%
- The particles of a solution are smaller than 1nm/10-9meter in diameter so they can not be seen in naked eyes.
- The path of light is not visible in a solution
- Depending up on the amount of solute present in a solution it can be classified in to.
- Dialuite
- Concentrated or
- Saturated solution.
- At any particular temperature a solution has dissolved as much solute as it is capable of dissolving is called a saturated solution.
- The amount of solute present in the saturated solution at this temperature is called its “Solubility”.
- If the amount of solute contained in a solution is less than the solution level is called an Unsaturated solution.
- The concentration of a solution means the amount of solute present in a given amount of solution.
- There are three main ways to expressing the concentration of a solution.
- Mass by Mass percentage of solution
= ( Mass of solute / Mass of solution ) x 100 - Mass by volume percentage of a solution = ( Mass of solute / Volume of Solution ) x 100
- Volume by volume percentage of a solution = ( Volume of solute / Volume of Solution ) x 100
- Mass by Mass percentage of solution
- Alloys are mixture of two or more metals or a metal and non – metal ,can be separated in to their components by physical methods.
Suspension
- Suspension is hetrogenous mixture.
- The solute particles do not dissolve but remain suspended through only the bulk of the medium.
- The particles of a suspension can be seen by the naked eye.
- A beem of light passing through it and make its path visible.
Colloidal Solution
- A colloid is a hetrogenous mixture.
- The size of particles of a colloid is too small
- Colloids are big enough to scatter a beam of light passing through it and make its path visible.
- They can not be separated from the mixture by the process of filtration.
- A special technique of separation known as centrifugation can be used to separate the Colloidal particles.
- The solute of colloid form the dispersed phase.
- The solvent of colloid is known as the dispersing medium.
- Colloids are classified according to the state of the dispersing medium and the dispersing phase.
Dispersed phase + Dispersing medium → Type of colloid
- Liquid + Gas → Aerosol
- eg :- Fog , Clouds ,Mist
- Solid + Gas → Aerosol
- eg :- Smoke , automobile exhaust
- Gas + Liquid → Foam
- eg :- Shaving Cream
- Liquid + Liquid → Emulsion
- eg :- milk , face cream.
- Solid + Liquid → Sol
- eg :- Milk of magnesia , mud
- Gas + Solid → Foam
- eg :- Foam , Rubber , Sponge , Pumice
- Liquid + Solid → Gel
- eg :- Jelly , Cheese , butter
- Solid + Solid → Solid sol
- eg :-Coloured gemstone , Milky glass
Different methods of separation
- Seperation of the volatile component (solvent) from its non – volatile solute by Evaporation.
- eg:- Dye from Blue or Black ink
Centrifugation
- Principle of centrifugation – The denser particles are forced to the bottom and the lighter particles stay at the top when spun rapidly.
- This process is applied for the separation of
- In Diagnostic laboratories for blood and Urine tests.
- In Diaries and home to Separate butter from cream.
- In washing machines to squeeze out water from wet clothes.
Separation of immiscible liquids
- The immiscible liquids separate out in layers depending on their densities.
- Examples :-
- To separate mixture of oil and water
- In the extraction of iron from its ore.
Chromatography
- It is a process of separation of components of a mixture .
- ‘Kroma’ means colour in greek.
- This technique was first used to separation of colours .
- It is mainly used for separation of those solutes that dissolves in the same solvent.
- Main applications of this technique was in the separation of
- Colours in a dye
- Pigments from natural colours
- Drugs from blood
Separation of two miscible liquids
- The method used is ‘Distillation’.
- Its principle is that boil without decomposition and have sufficient difference in their boiling points.
- If the difference of boiling points of mixtures were less than 25K ‘fractional distillation’ process is used.
- Air is a homogenous mixture and can be separated into its components by “fractional distillation”
- The Crystillaion mathod is used to purify solids.
- It is a process that seperates a pure solid in the form of its crystals from a solution.
- Eg :- Separation of Copper Sulphate from China dish
- On the basis of chemical composition substance cab be classified in to elements and compounds.
- Robert Boy le was the first Scientist to use the term element in 1661
- The French Chemist Antoine Laurent Lavoisier was the first to establish an experimentally useful definition of an element.
- According to Lavoisier an element is a basic form of matter that can not be broken down to simpler substances by chemical reactions.
- Elements can be normally divided in to follows,
- Metals
- Non – metals
- Metalloids
- Ex. of Metals – Gold , Silver, Copper, Sodium, Potassium etc
- ‘Mercury’ is the only metal that is liquid at room temperature.
Eg. Of non – metals – Hydrogen , Oxygen , Carbon , Iodine ,Bromine, Chlorine etc - The elements shows intermediate properties between those of metals and non – metals
are called Metalloids
Eg. of Metalloids – Boron , Silicon , germanium etc - Naturally occurring elements are ’92’ numbers.
- Eleven elements are “Gaseous state at room temperature”.
- Two elements are liquid state at room temperature.
- They are Mercury and Bromine.
- Elements like “Gallium “ and Cesium become liquid at a temperature slightly above room temperature that is „ 303K‟.
- The concentration of solution is the amount of solute present per unit volume or per unit mass of the Solution.
- The dispersed phase and the dispersion medium are related to Colloids.
- A compound is a substances composed of two or more different types of elements , chemically combined in a fixed proportion.
- Properties of compounds are different from its
- Constituent elements
- Properties of Mixtures shows properties of its elements.