Chemistry

• Everything in this universe is made up of material which scientists have named "matter"
• Examples of matter


  • Air
  • Food
  • Stones
  • Clouds
  • Stars
  • Plants
  • Animals
  • Water
  • Sand
• Matter


  Things that occupy space and have mass
• Early Indian philosophers classified matter in the form of five basic elements — the "Panch Tatva" — air, earth, fire, sky and water
• Ancient Greek philosophers had arrived at a similar classification of matter
• Modern day scientists have evolved two types of classification of matter based on their physical properties and chemical nature
• Activity 1.1: Dissolving salt/sugar in water

  1. Take a 100 mL beaker

  2. Fill half the beaker with water and mark the level

  3. Dissolve some salt/sugar with a glass rod
• When we dissolve salt in water, the particles of salt get into the spaces between particles of water
• Activity 1.2: Diluting potassium permanganate solution

  1. Take 2-3 crystals of potassium permanganate and dissolve in 100 mL of water

  2. Take out 10 mL of this solution and put it into 90 mL of clear water

  3. Keep diluting the solution like this 5 to 8 times
• The particles of matter are very small
• Particles of matter


  • They have space between them
  • They are continuously moving
  • They attract each other
• Activity 1.4: Diffusion of ink and honey in water


  1. Put a drop of blue/red ink along the sides of one beaker and honey in the same way in another beaker

  2. Leave them undisturbed
• Particles of matter are continuously moving, they possess kinetic energy which increases with temperature
• Intermixing of particles of two different types of matter on their own is called diffusion, which becomes faster on heating
• Particles of matter have force acting between them, which keeps the particles together. The strength of this force varies for different types of matter
• Matter exists in three different states - solid, liquid and gas, due to variation in the characteristics of the particles
• Solid state


  • Definite shape, distinct boundaries, fixed volume, negligible compressibility, rigid
• Liquid state


  • No fixed shape, fixed volume, flow and change shape, fluid
• Sponge


  • Minute holes
  • Air is trapped
  • Air is expelled out when pressed
• Liquids


  • Have no fixed shape but have a fixed volume
  • Take up the shape of the container
  • Flow and change shape
  • Are not rigid but can be called fluid
• Solids, liquids and gases can diffuse into liquids
• Rate of diffusion of liquids is higher than that of solids
• Gases


  • Are highly compressible
  • Large volumes can be compressed into a small cylinder and transported easily
• Smell of hot cooked food reaches us in seconds due to high speed of gas particles and large space between them
• Pressure exerted by gas


  Due to force exerted by gas particles per unit area on the walls of the container
• Liquefying gases


  1. Applying pressure

  2. Reducing temperature
• Compressing a gas increases the pressure