Class 9th Chemistry Chapter 5 Notes
Important Notes of Class 9th Chemistry Chapter 5 Notes Urdu Medium written by Honorable Sir M. Shahid Suib. These notes are very helpful in the preparation of Physical States of Matter Class 9 Notes for students of the Class 9th Chemistry Chapter 5 Notes Urdu Medium and these are according to the paper patterns of all Punjab boards.
Summary and Contents:
Topics which are discussed in the notes are given below:
- Here are the detailed chemistry chemistry chapter 5 class 9 notes to help you prepare for your exams.
- Complete Exercise MCQs of Chapter No.5 Physical States of Matter in Urdu Medium
- Complete Exercise Short Questions with Answers of Chapter No.5 Physical States of Matter in Urdu Medium
- Major Concepts: Gaseous State: 1. Typical properties 2. Laws related to gases, Liquid State: 1. Typical Properties , Solid State: 1. Typical Properties 2. Types of Solids 3. Allotropy
- GASEOUS STATE: TYPICAL PROPERTIES:
- Gases have similar physical properties. A few typical properties are discussed here.
- Diffusion: Gases can diffuse very rapidly. Diffusion is defined as spontaneous mixing up of molecules by random motion and collisions to form a homogeneous mixture. Rate of diffusion depends upon the molecular mass of the gases. Lighter gases diffuse rapidly than heavier ones. For example, H2, diffuses four times faster than O2, gas.
- Effusion: It is escaping of gas molecules through a tiny hole into a space with lesser pressure. For example, when a tyre gets punctured, air effuses out. Effusion depends upon molecular masses, lighter gases effuse faster than heavier gases.
- Pressure: Gas molecules are always in continuous state of motion. Hence, when molecules strike with the walls of the container or any other surface, they exert pressure. Pressure (P) is defined as the force(F) exerted per unit surface area (A). P=F/A
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- The SI unit of force is Newton and that of area is m^2. Hence pressure has SI unit of N m^-2. It is also called Pascal (Pa), One Pascal (Pa) = 1 Nm^-2
- Standard Atmospheric Pressure: It is the pressure exerted by the atmosphere at the sea level. It is defined as the pressure exerted by a mercury column of 760 mm height at sea level. It is sufficient pressure to support a column of mercury 760 mm in height at sea level.
- Compressibility: Gases are highly compressible due to empty spaces between their molecules. When gases are compressed, the molecules come closer to one another and occupy less volume as compared to the volume in uncompressed state.
- Mobility: Gas molecules are always in state of continuous motion. They can move from one place to another because gas molecules possess very high kinetic energy. They move through empty spaces that are available for the molecules to move freely. This mobility or random motion results in mixing up of gas molecules to produce a homogeneous mixture.
- LAWS RELATED TO GASES: Boyle's Law: In 1662 Robert Boyle studied the relationship between the volume and pressure of a gas at constant temperature. He observed that volume of a given mass of a gas is inversely proportional to its pressure provided the temperature remains constant.
- Charles's Law: The relationship between volume and temperature keeping the pressure constant was also studied. French scientist J. Charles in 1787 presented his law that states "the volume of a given mass of a gas is directly proportional to the absolute temperature if the pressure is kept constant'. When pressure P is constant, the volume V of a given mass of a gas is proportional to absolute temperature T.
- In which units' body temperature is measured? Body temperature is measured in Fahrenheit scales. Normal body temperature is 98.6 °F, it is equivalent to 37 °C. This temperature is close to average normal atmospheric temperature. In winter atmospheric temperature falls lower than that of our body temperature.According to principle of heat flow, heat flows out from our body and we feel cold. To control this outward flow of heat, we wear black and warm clothes. To maintain body temperature we use dry fruits, tea, coffee and meats, etc.
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