9 Class Science Chapter 2 Is Matter Around Us Pure ? Notes
|Chapter Name||Is Matter Around Us Pure ?|
|Category||Class 9 Science Notes|
Class 9 Science Chapter 2 Is Matter Around Us Pure ? Notes. here we will be learn about MATTERS , Mixture , Solution , Concentration , Suspension , Colloidal solutions , Physical Properties , Physical Change , Chemical Change , Elements , Compounds etc.
Class 9 Science Chapter 2 Is Matter Around Us Pure ? Notes
📚 Chapter = 2 📚
💠 Is Matter Around Us Pure ? 💠
❇️ MATTERS :-
🔹Anything which occupies space and has mass is called matter.
🔹 Matter can be divided in two categories.
- ( I ) Pure Substance
- ( II ) Impure Substances (Mixtures)
❇️ ( I ) Pure Substance :-
🔹 Pure substances means that all elements have same chemical properties. A pure substance is made up of same kind of elements.
🔶 Pure :- ‘Pure’ word means that there is no mixing in a substance. But according to scientific language all things are mixture of so many substances, not of single one. That’s why they are not pure. E.g. Milk, water, fat, etc.
🔶 Substance :- A substance is a kind of matter that cannot be separated into other kind of matter by any physical process. Apure substance is made up of same kind of elements.
❇️ What is a Mixture?
🔹 It is a substance in which two or more substances (element or compound) are simply mixed together in any proportion.
🔹 Examples :- The air is a mixture of oxygen, nitrogen, carbon dioxide and water vapour.
❇️ Types of Mixture :-
🔹 Mixture is of two types :
- Homogenous mixture
- Heterogenous mixture
🔶 Homogenous Mixture :-
🔹 These types of mixtures have no visible boundaries of separation between the various constituents.
🔹 Example :- Sugar in water. It has a uniform composition throughout its mass.
🔶 Heterogenous Mixture :-
🔹 These types of mixtures have visible boundaries of separation between the various constituents.
🔹 Example :- Mixture of sugar and sand. It does not have a uniform composition throughout its mass.
❇️ Differences between Homogeneous and Heterogeneous :-
|Homogenous Mixtures||Heterogeneous Mixtures|
|They have a uniform composition throughout||They have a non-uniform composition|
|We cannot separate the components of the mixture through physical processes||We can separate the components through physical processes|
|Components cannot be seen through naked eyes||Components can easily be seen through naked eyes|
|The mixture is in single phase throughout||The substances can be of two different phases and we may see separate layers of the substances|
|Example :- A mixture of water and milk||Example :- A mixture of oil in water|
❇️ Solution :-
🔹 A solution is a homogenous mixture of two or more substances. E.g., Nimboo pani, soda water.
🔹 A solution has a solvent and a solute as its components.
🔶 Solvent :- The component of the solution that dissolves the other component in it is called the solvent.
🔶 Solute :- The component of the solution that is dissolved in the solvent is called the solute.
❇️ Properties of a Solution :-
- A solution is a homogenous mixture.
- We cannot see the particles of a solution through naked eyes as they as are small as 1 nanometer in diameter.
- The path of light is not visible through the solution. The particles of a solution do not scatter light through them as they are extremely small.
- We cannot separate the particles of a solution by methods of filtration.
❇️ Concentration of a solution :-
🔶 Saturated solution :- When no more amount of solute can be dissolved in a solution at a given temperature, it is called a saturated solution.
🔶 Unsaturated solution :- When more amount of solute can be dissolved in a solution at given temperature, it is called a saturated solution.
🔶 Solubility :- The amount of the solute present in the saturated solution at the given temperature is called its solubility.
❇️ Concentration :-
🔹 Concentration refers to the amount of a substance per defined space or can be defined as the ratio of solute in a solution to either solvent or total solution.
❇️ Two methods of finding concentration of solution :-
🔹Mass by mass percentage of a solution = (Mass of solute/Mass of solution) x100
🔹Mass by volume percentage of a solution = (Mass of solute/Volume of solution) x100
❇️ Suspension :-
🔹 suspension is formed when two or more substances non-uniform manner. Heterogeneous mixtures are suspensions. The solute does not mix with the solvent and can be viewed through naked eyes.
❇️ Properties of Suspensions :-
- A suspension is a heterogeneous mixture.
- We can see the particles of suspensions through naked eyes.
- We can see the path of light through the particles of a suspension.
- The particles of suspension tend to settle down when left undisturbed. Then, they can be separated using filtration.
❇️ Colloidal solutions :-
🔹 A colloidal solution or a colloid is a uniform solution of two or more substances. The particles are relatively very small that the solution appears as a homogeneous mixture but it is not.
❇️ Properties of colloids :-
- Colloids are heterogeneous in nature.
- The particles of a colloid cannot be seen through naked eyes.
- The particles scatter a beam of light passed through a colloid and produce Tyndall effect.
- Colloids are stable in nature. The particles of colloids do not settle down if left uninterrupted.
- We cannot separate the particles of a colloid through filtration. We use a method called Centrifugation to separate the particles of a colloid.
❇️ Tyndall Effect :-
🔹 When a beam of light is passed through a colloid the particles of the colloid scatter the beam of light and we can see the path of light in the solution.
🔹For Example :- when a ray of light enters a dark room it is scattered by the dust particles present in the air and we can see the path of light clearly.
❇️ Methods of Separation of Mixtures :-
🔶 Evaporation :-
🔹 Basic principal :- Out of the two components of a mixture one can evaporate [i.e., has less boiling point] and other has higher boiling point.
🔶 Centrifugation :-
🔹 Basic principle :- Separation of Substances or particles on the basis of their density, when mixture is rotated very fast, then denser particles are forced at the bottom and lighter particles stay above.
🔹 Applications :-
- Used in diagnostic labs for blood and urine tests.
- Used in dairies and home to separate butter from cream.
- Used in washing machines dryers to squeeze out water from clothes.
🔶 Separating Funnel :-
🔹 Basic principle :- Two immiscible liquids (which do not dissolve in each other) can be easily separated by putting in a separating funnel.
🔹 Applications :-
- Separation of oil from water.
- Extraction of iron from its ore. Lighter slag is removed from above the molten iron.
🔶 Sublimation :-
🔹 Basic principle :- Out of the two components, one will sublime (directly converts to gas from solid) and other will not.
🔹 Applications :- Camphor, naphthalene, anthracene, NH,Cl can sublime.
🔶 Chromatography :-
🔹 Basic principle :- Coloured components of a mixture can be separated by using an Adsorbent on which they are adsorbed at different rates.
🔹 Applications :-
- To separate colours of a dye.
- To separate pigments from natural colours like chlorophyll.
- To separate drugs from blood.
🔶 Distillation :-
🔹 Basic principle :- Based on Separating mixture of miscible liquids having different boiling points, followed by condensation. Out of the two components one has a lower boiling point and other has higher boiling point. This is used to separate two or more miscible liquids.
- In petroleum refineries, petrochemical and chemical plants, natural gas processing and cryogenic air separation plants.
- In oil refineries to separate crude oil into useful substances (or fractions).
- In the separation of oxygen, liquid nitrogen and argon from air.
🔶 Crystallisation :-
🔹 Basic principle :- To remove impurities from a mixture by first dissolving in a suitable solvent and then crystallising out one component.
🔹 Applications :-
- Purification of salt from sea water.
- Separation of crystals [e.g., alum (phitkari), copper sulphate] from their impure crystals.
❇️ Physical Properties :-
🔹 Properties of a substance such as rigidity, colour, fluidity, boiling point, melting point, density and hardness which we can observe are called as Physical Properties.
❇️ Physical Change :-
🔹 When physical properties of a substance change it is known Physical Change. When we convert a substance from one state to another, such as a solid into a liquid or vice-versa, it is also a physical change as only the physical nature of the substance changes without affecting its chemical nature.
🔹 For Example :- Change of ice into water. The chemical properties of water remain the same.
❇️ Chemical Change :-
🔹 When the chemical properties or chemical composition of a substance gets altered it is called a chemical change. It is also called as a Chemical Reaction.
🔹 For Example :- Burning of paper
❇️ Elements :-
🔹 An element is the simplest form of matter. Elements cannot be broken down into further elements by chemical reactions.
🔹 Elements are further characterized as Metals, Non-Metals and Metalloids
🔶 Metals :- Silver, Mercury, Copper, Gold
- Metals are lustrous (shiny)
- Metals conduct heat and electricity
- Metals have a silver-grey or gold-yellow colour
- We can hammer metals and form thin sheets (Malleability)
- We can convert metals into wires (Ductility)
- Metals always produce a ringing sound if they are hit (Sonorous)
🔶 Non-Metals :- Carbon, lodine, Chlorine, Oxygen, Hydrogen
- Non-Metals do not conduct heat and electricity
- Non-Metals are not sonorous, lustrous or ductile
- Non-Metals have varied colours
🔶 Metalloids :- Silicon, Germanium
- They show some properties of metals and some of the non-metals.
❇️ Compounds :-
🔹 It is a substance that consists of two or more substances. These substances are combined chemically with each other in fixed proportions. The properties of a compound are different than that of its constituents.
🔹 For Example :- Ammonium Sulphate, Sulphur Chloride, Water.
❇️ Difference between Mixtures vs. Compounds :-
|Elements or compounds are simply mixed so no new substance is formed.||Substances are reacted together with each other to make a new substance.|
|Elements do not combine in a fixed ratio.||Composition of the components is fixed i.e., they combine together in a fixed radio according to their masses.|
|A mixture shows the properties of its components.||Compound doesn’t show the properties of component elements.|
|Components can be easily separated by any mechanical method which is suitable.||Components can’t be separated from each other by simple mechanical methods.|
|e.g., Mixture of iron and sulphur.||e.g., Iron and sulphur react to from iron sulphide.|
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