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Showing posts with label Chemistry. Show all posts
Showing posts with label Chemistry. Show all posts
Class 9th Chemistry-Chapter 3 Notes
- During a chemical reaction, the sum of the masses of the reactants remains unchanged, his is known as Law of Conservation of Mass.
- In a pure chemical compound, elements are always present in a definite proportion by mass.
- An atom is the smallest particle of matter/element that can exist independently and retain all its chemical properties.
- A molecule is the smallest particle of an element or compound capable of independent existence under ordinary conditions.
- Compounds composed of metals and non-metals contain charged species, the species are known as ions.
- A group of atoms carrying a charge is known as poly-atomic ion.
- The Avogadro constant 6.022 x 1023 is defined as the number of atoms in exactly 12 g of carbon -12.
- The mole is the amount of substance that contains the same number of particles (atoms/ ions/ molecules/ formula units etc.) as there are atoms in exactly 12 g of carbon - 12.
- Mass of 1 mole of a substance is called its molar mass.
Class 9th Science-Chemistry Chapter 2 Notes
- A mixture is that one substance(element or compound) mixed in any proportion.
- Mixtures can be separated into pure substances using appropriate separation techniques.
- A solution is a homogeneous mixture of two or more substances.
- A type of solution in which particles are uniformly spread and is heterogeneous is known as Colloidal Solution.
- A type of solution in which solids are dispersed in the liquid and are visible with the naked eye is called Suspension.
- Mass percentage of solution = Mass of solute / Mass of Solution x 100.
- The scattering of a beam of light is called the Tyndall effect.
Class 9th Science Chemistry Chapter 1 Notes
- Matter is made up of particles.
- Particles of matter attract each other.
- Matter can exist in 3 states. Solid, Liquid and Gas.
- Solid that stretch on applying force are known as elastics.
- The temperature at which a solid melts to become liquid at the atmospheric pressure is called its melting point.
- 0 C = 273.16 K
- 1 C = 273.16 + 1 K
- The boiling point of water is 100 degrees C and 373 K(100 +273).
- Factors affecting evaporation are increase of surface area, increase in temperature, decrease in humidity, increase in wind speed.
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