Grade 9 chem-Chapter 1-matter in our surroundings-shilpa.pptx

chemistry

1. Matter in our surroundings

2. Road map List the general properties of matter Activities to prove the properties of matter Interconversion of states of matter Temperature scales Latent heat Evaporation & the factors affecting it.

3. Pretest: 1. Arrange the following in the increasing order of force of attraction between the atoms. water, nitrogen gas, wood 2. You cannot swim through a piece of wood. Explain 3. Out of solids , liquids and gases, the particles of which one has the least kinetic energy? 4. What is the fullform of LPG? 5. Which property of matter(or what is done to petroleum gas to) is used in making LPG?

4. WHAT IS A MATTER? ANYTHING THAT HAS MASS AND OCCUPIES SPACE IS CALLED A MATTER Which of the following is not a matter.? Books, shelves, love, friendship, lap top, desk, pillow, anger, cupboard, door, sadness, icecream , happiness. .

5. HW Research and write about Antimatter. Stick a picture or draw a well labelled diagram of antimatter

6. General properties of matter All matter is made up of very small particles . Particles of matter have space between them. Particles of matter move continuously Particles of matter have force of attraction between them .

7. Suggest an activity to prove that particles of matter are very small . https://www.youtube.com/watch?v=nvbJSKhVWdU https://www.youtube.com/watch?v =OjElFVfHdWs

8. Aim: To prove that particles of matter are very small. Apparatus & materials : KMnO4, beaker, syringe, water., stirrer. Procedure: 1. take 6 beakers and fill 100 ml water in each. 2. Add 0.5 g of potassium permanganate into the first beaker. 3. Stir the mixture until all particles dissolve well. 4. Take 10 ml of solution with the help of a syringe and add it to the second beaker. 5. Repeat the same step till the last beaker. Observe: Colour persists even after several dilutions. Result: As colour persists after so many dilutions we can say that particles of matter are really very small.

9. Suggest an activity to prove that particles of matter have space between them. https://www.youtube.com/watch?v=8x-miemNfDU

10. Aim: to prove that particles of matter have space between them. Materials: Beaker, water, sugar & stirrer. Procedure: 1. take a beaker. 2. Add water to 100 ml mark. 3. Mix 5 g of sugar in the water. 4. Stir and dissolve the sugar. 5. Observe the level of the solution. Observation: The level of solution remains same. Result: As the level does not increase, we can say that particles of sugar has taken place between the particles of water. So this proves particles of matter have space between them

11. CRITERIA SOLIDS LIQUIDS GASES SHAPE AND VOLUME RIGIDITY FORCE OF ATTRACTION KINETIC ENERGY COMPRESSIBILITY DENSITY

12. CRITERIA SOLIDS LIQUIDS GASES SHAPE AND VOLUME DEFINITE SHAPE & DEFINITE VOLUME NO DEFINITE SHAPE BUT DEFINITE VOLUME NO DEFINITE SHAPE & NO DEFINITE VOLUME RIGIDITY ARE RIGID NO RIGIDITY NO RIGIDITY FORCE OF ATTRACTION VERY HIGH FORCE OF ATTRACTION BETWEEN THE PARTICLES MODERATE FORCE OF ATRRACTION LEAST FORCE OF ATTRACTION KINETIC ENERGY LEAST KINETIC ENERGY GOOD AMOUNT OF KINETIC ENERGY VERY HIGH KINETIC ENERGY COMPRESSIBILITY NEGLIGIBLE COMPRESSIBILITY COMPRESSSIBLE TO CERTAIN EXTENT HIGHLY COMPRESSIBLE DENSITY HIGH DENSITY LESS DENSER THAN SOLIDS LEAST DENSE

13. What is Diffusion ? The intermixing of the particles of two /more media without any external force(on their own) due to movement of the particles from higher concentration to lower concentration is called diffusion.

14. Diffusion is faster in hot water compared to cold water. Explain In the  hot water  the molecules MOVE  faster  than in the  cold water as the kinetic energy of the molecules is higher. This causes the material in the  hot water  to actually  diffuse faster.

15. The smell of a food that is being cooked reaches several meters while that of food cooked earlier doesn’t. Explain The  smell of hot  sizzling  food reaches  us several metres away because  SMELL OF FOOD diffuses faster in air when it is hot due to higher kinetic energy and we  smell  it no time. Whereas the smell of cold  food doesn’t diffuse much due to very less kinetic energy and we have to go close to have a smell  of it.

16. Melting point and boiling point The temperature at which a given solid melts is called its melting point The temperature at which a liquid boils is known as the boiling point of that liquid. 

17. ` Define Heat : It is a form of energy. Define Temperature: It is the measurement of heat energy .

18. Temperature scales

19. Convert the following : ( just add 273 to the given value) 100  C = _____________ K Ans : 100 + 273 = 373 K 250  C =______________K -25  C = ______________K -200  C = ____________K

20. Convert the following to Celsius scale ( subtract 273 from the given value) 473 K = ___________  C 312 K = ___________  C Do it yourself.

21. Convert Celsius scale to Fahrenheit scale Formula: 110  C = ________  F = 9/ 5 (110) + 32 = [9 X 22] + 32 = 198 + 32 =230  F 50  C = _________  F -195  C = ________  F

22. Convert Fahrenheit scale to Celsius scale Formula  C = 5/9(  F -32) 77  F = _______ C 104  F = _______ C

23. Inter-conversion of states of matter

24. Latent heat of fusion Definition: The amount of heat required to convert one kg of solid into liquid at it melting point and at the same atmospheric pressure is called Latent heat of Fusion

25. Latent heat of vaporisation The amount of heat required to convert one kg of liquid into gas at it boiling point and at the same atmospheric pressure is called Latent heat of Vaporisation.

26. Graph of time versus temperature

27. A B C D 100

28. The steam at 100 C can cause severe burns compared to boiling water at the same temperature. Explain. The steam at 100  C has latent heat of vaporization. It is the extra heat that keeps it gaseous form. So though both of them are at same temperature steam has more energy and so it causes severe burns.

29. Which one of these is colder? -Ice at 0 C or ice cold water at 0 C The ice at 0 degree Celsius is colder than ice cold water at the same temperature. This is because the ice cold water has latent heat of fusion to be in liquid state. So it has extra energy which the ice lacks and so ice is colder.

30. Define sublimation The change of state of matter directly from solid to gaseous state or vice versa without going into the liquid state is called sublimation. Examples of substances that undergo sublimation: Naphthalene balls Camphor Ammonium chloride Iodine crystals Dry ice

31. How can you liquefy gases? Gases can be liquefied by: Applying Pressure . (compress) Reducing the temperature (cooling)

32. What is dry ice ? Dry ice is solid form of carbon dioxide(CO 2 ) Its temperature is -78 degree Celsius. As it sublimes it doesn’t leave any residue or liquid so it is called Dry Ice.

33. Where is dry ice used?/ Applications of dry ice To create smoky effect in stage performances. To store frozen food items. To stop ice sculptures from melting To preserve organs for transplantation

34. Evaporation The conversion of liquid state to gaseous state at any temperature even below the boiling point is called evaporation.

35. Factors affecting evaporation Temperature : As temperature increases the rate of evaporation increases. Humidity : If humidity is more, evaporation will be less and vice-versa. Surface area : More the surface area more the evaporation. 4. Wind speed : Wind speed enhances the rate of evaporation . 5. Nature of the material : Different materials evaporate at different temperatures.

36. Differentiate between evaporation and boiling boiling Boiling is a bulk phenomena. The entire liquid boils. Boiling takes place at the boiling point. Boiling temperature is not affected by surface area. Evaporation Evaporation is a surface phenomena. It takes place only at surface. Evaporation takes place at any temperature. Evaporation depends on the surface area.

37. Give reasons: Sponge is compressible though it is a solid. Ice floats on water. Camphor and Naphthalene disappears without leaving any residue. Evaporation is a surface phenomena People sprinkle water on the terraces of their houses during summers. Water kept in an earthen pot becomes cool during summers. Dry ice is used for storing frozen foods .

38. Sponge is compressible though it is a solid.   Sponge  is a porous  solid. It has minute holes, in which air is trapped, when we press it, the air is expelled out and we are able to compress it.

39. Ice floats on water. Explain Generally liquids have less density than solids but ice in solid state has less density than water . In solid state the bond formation leaves lot of space between the molecules making it less dense so it floats on water.

40. Camphor and Naphthalene disappears without leaving any residue Camphor has the property to sublimate i.e it directly changes from solid to gas without going into liquid state. So they don’t leave any residue.

41. Evaporation is a surface phenomena Evaporation is a surface phenomenon  because it occurs on the  surface . During  Evaporation , the molecules of the water at the surface absorb heat energy and the kinetic energy of the molecules increases. When their energy exceeds, they leave in gaseous form from the surface .

42. People sprinkle water on the terraces of their houses during summers. This is done to keep the houses cool. When people sprinkle water, water absorbs heat equivalent to latent heat of vaporization from the roof leaving it cooler.

43. Water kept in an earthen pot becomes cool during summers. In an  earthen pot ,  water  gets evaporated through the pores.. The energy to evaporate is taken from the  water  itself, it leads to a lowering of temperature of the remaining amount of  water . So the water in the earthen pots become cooler.

44. Dry ice is used for storing frozen foods. Dry Ice  is very cold . Its temperature is -78.5°C.  Dry Ice  is widely  used  as it is simple to  freeze  and easy to handle using insulated gloves. And in critical conditions it sublimes to gas leaving no liquid and so the frozen foods will be safe.

45. we see water droplets on the outer surface of a glass containing ice-cold water? The water vapour present in air, on coming in contact with the cold glass of water, loses energy and gets converted to liquid state, which we see as water droplets.

46. we wear cotton clothes in summer Cotton clothes are good absorbent of water. in summers we perspire a lot and cotton clothes absorb it well . As the sweat evaporates , it takes up heat from body surface and leaves the body cooler