1 World of Matter What is matter? Definition Matter is something that occupies space and has mass. Checkpoint Identify matter and non-matter from the following air, temperature, table, thoughts, emotions, water, pen, prayer and phone. Matter Non-matter Activity: What is matter made up on? Take a piece of chalk and break it in to half. Do both halves have the same properties as the original chalk? Continue breaking the chalk in to smaller and smaller pieces. Does each one of those pieces still have all the properties of chalk? Can you say that chalk is made up of small particles of chalk? Activity: Some properties of matter Take a beaker and fill it with water. Add few crystals of potassium permanganate to it. Don t stir the solution. What do you observe?
2 Does the color spread out in water? How does the color spread without you stirring the solution? Where have the crystals of potassium permanganate gone? Based on this experiment, what can you say about matter is it continuous or is there gap between the particles of matter? Activity: Is space between the particles of matter? Dissolve some salt in water. You will observe that it dissolves in water. The salt molecules occupy space between water molecules as seen in the above activity. Continue adding more salt to the water till salt stops dissolving in water. Why does this happen? How can you get some more salt dissolved in water (without adding more water)? Checkpoint Explain how the smell of an ignited incense stick spreads throughout the room?
3 Properties of Matter States of matter Matter is known to exist in 5 states. How many states do you know of? Give some examples of objects in the different states. States of matter Examples Definition Plasma: Bose Einstein Condensate:
4 Activity: Solids, liquids and gas Fill up the following table for different everyday objects Sample State Occupies space? Fixed shape? Fixed volume? water air block of wood salt toothpaste honey paper rubber band Based on your observations identify the properties of a solid, liquid or gas? Solid Liquid Gas Checkpoint Why is it easier to walk through air than through water?
5 Activity: Viscosity Place a glass plate on a block of wood as shown in the adjoining figure to create an inclined plane. Drop 2-3 drops of water at the top end of the glass plate and note the time it takes for water to reach the bottom. Repeat the experiment with honey and kerosene. Liquid Water Honey Kerosene Time taken Why do different liquids take different amount of time to reach the bottom happen? Effect of pressure of a gas Your mother uses LPG (liquefied petroleum gas) at home for cooking. The temperature of the gas cylinder is the same as the outside temperature. How do they manage to keep the gas in the liquid state within the cylinder? Changing the state of matter Activity: Melting point and boiling point Take some ice in a beaker and heat it slowly till all the ice has completely melted. Note the temperature at regular intervals of time. (Make sure that the bulb of the thermometer is completely immersed in ice/water at all times). Continue heating and noting the water till it begins to boil. Plot the temperature time graph based on the readings taken by you. How can you identify the melting point and boiling point of water from the graph?
6 Explain why the state of water changes on heating? Is the change in state of a substance a physical change or a chemical change? Is this change permanent? When you do this activity, you might find that temperature of ice never falls below 0 C or that water begins to boil below 100 C. Why does this happen? Can you identify all possible causes that can introduce an error in this activity? Will the temperature recorded by you ever exceed 100 C? What is the effect of increasing the pressure on the boiling point of water?
7 If some salts are dissolved in water, will it affect its boiling point? Definition Latent Heat: Checkpoint Why do we use pressure cookers to cook our food? Food takes more time to cook on a hill station, why? Measuring temperature You must have heard of two scales used to measure temperature Celsius and Fahrenheit. Do you know there is a third scale called the Kelvin scale? The three scales are named after three scientists
8 Lord Kelvin Daniel Fahrenheit Anders Celsius Find the formulae used convert the temperature from one scale to another. Activity: Sublimation Take some ammonium chloride in a china dish. Place an inverted glass funnel with a plug on its stem over the dish as shown in the adjoining figure. Slowly heat the dish and observe the crystals of ammonium chloride. Does ammonium chloride melt on heating? What do you observe on the inside surface of the glass funnel?
9 Definition Sublimation: Identify at least two more substances that sublimate. 1. 2. Activity: Evaporation Take 5 ml of water in a dish. Keep the dish out in sunlight. You will observe that after sometime all the water in the dish has disappeared. Where has the water gone? It is possible that the water got converted to water vapor? But how is this possible without water reaching its boiling point? Definition Evaporation: Activity: Factors effecting evaporation Take 5 ml of water in a test tube and 5 ml in a dish. Keep both of these in sunlight and note the time taken for water to completely evaporate. Next take 5 ml of water in two dishes. However, place one dish under the fan and other away from the fan. Note the time taken for water to completely evaporate.
10 Repeat your activity on a rainy day and compare the time taken for water to evaporate on a rainy day to the time taken on a dry sunny day. Setup details 5 ml of water in a test tube Kept in sunlight 5 ml of water in a dish Kept in sunlight 5 ml of water in a dish Under the fan 5 ml of water in a dish Away from the fan 5 ml of water in a dish Summer 5 ml of water in a dish Rainy day Time taken Factors that affect the rate of evaporation Activity: Condensation Pour some cold water in a glass and keep it on a table for some time. What do you observe on the outside surface of the glass? Where did this water come from?
11 Checkpoint How does water in an earthen pot become cool in summer?