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Effects of Heat

  1. 1. Effects of Heat 1 © Jnana Prabodhini Educational Resource Centre
  2. 2. There are three types of item solid, liquid and gas. Wax , snow are examples of solid. Examples of liquid are water , milk, oil . Examples of gas are air, steam . 2 © Jnana Prabodhini Educational Resource Centre
  3. 3. We can see the change in solid , liquid , gas if they are heated. When heat given to solids it's size varies , and converted in to fluid . When heat is given to liquids it start boiling and converted to gas form . If heat is provided to gas it is expand. 3 © Jnana Prabodhini Educational Resource Centre
  4. 4. If heat is provided in all three stages first of all the temperature of substance increases . Then at specific temperature solid changes to liquid and liquid changes to gas . The change in physical state of substance due to heat is called as transition of foods . 4 © Jnana Prabodhini Educational Resource Centre
  5. 5. When heat is given to item , it changes its state similarly if heat is taken out from item it changes its state. If heat is taken out or cool down it changes it's state to water. If water is cooled down it changes to ice. If ice is cooled down it becomes hard. To remove heat means cooling down substance , due to cooling the temperature of substance decreases. 5 © Jnana Prabodhini Educational Resource Centre
  6. 6. To change the state of item either heat need to be provided or heat need to be taken out. Changing the state from solid to liquid is called as liquefaction 6 © Jnana Prabodhini Educational Resource Centre
  7. 7. The temperature at which the substance changes its state from solid to liquid is called as melting point of the substance . The temperature at which liquid changes to gas state is called as boiling point of the substance. 7 © Jnana Prabodhini Educational Resource Centre
  8. 8. The process in which substance changes its state from gas to liquid is called as condensation. The process in which substance changes its state from liquid state to solid state is called as freezing. The temperature at which substance changes its state from liquid to solid is called as freezing point of the substance. 8 © Jnana Prabodhini Educational Resource Centre
  9. 9. The unit to measure temperature is degrees Celsius (°c) The melting point of ice is 0°c (zero degrees Celsius ). The boiling point of water is 100°c (hundred degrees Celsius ). The freezing point of water is 0°c (zero degrees Celsius). 9 © Jnana Prabodhini Educational Resource Centre
  10. 10. If ice is heated it changes to the water. While the ice began to heat its temperature is zero degrees Celsius. If a substance is heated it should show rise or increase in the temperature of the substance. But if ice is heated it started its transition and changes to water but does not seem to increase temperature of ice . The temperature of the ice stays 0°c until the transition of water completes. 10 © Jnana Prabodhini Educational Resource Centre
  11. 11. After completing the transition of ice through water if heating continues the water temperature seems to rise. While solid substance changes to liquid , we can not see the rise in temperature. It is used for the transition . 11 © Jnana Prabodhini Educational Resource Centre
  12. 12. If water is heated it starts boiling at 100°c and converts to steam. This time it does not show rise in temperature. It is used for the transition . 12 © Jnana Prabodhini Educational Resource Centre
  13. 13. If solid substance is heated , expansion occur before converting to fluid .The heat increases the length of iron rod due to expansion. It is seen , measured on the lever fixed on stand. If a coin is heated, it also expands. A coin passing through two nails can not pass through after heating it because it is expanded and the size is increased, Can pass through again after cooling. 13 © Jnana Prabodhini Educational Resource Centre
  14. 14. Different solid substances of different materials expand differently. If a strip of iron and copper is heated it bends towards iron because expansion of copper is more then expansion of iron . Such cables are used to maintain the temperature of the electronic devices. 14 © Jnana Prabodhini Educational Resource Centre
  15. 15. If liquid is heated it expands. It can be checked by take a test tube filled with colored water and put hair tube in it. When water is heated it expands. Notice the increased of water level in a hair tube . When milk is heated it seems coming up. After cooling down the water level and milk level comes down. 15 © Jnana Prabodhini Educational Resource Centre
  16. 16. If gas is heated it expands. Fix a balloon on a narrow mouth glass bottle. Now heat the glass bottle , the air in the bottle expands and enters in the balloon and the balloon is expanded. If heating the glass bottle is stopped the air cools slowly and it remains as it was. 16 © Jnana Prabodhini Educational Resource Centre
  17. 17. If substance is heated it expands similarly if heat is taken out of substance it contracts. 17 © Jnana Prabodhini Educational Resource Centre
  18. 18. To know the heat in a substance or level of temperature thermometer is used. The properties of expansion and contraction of substance due to heat is used in thermometer. 18 © Jnana Prabodhini Educational Resource Centre
  19. 19. Thermometer consist of a very small glass tube, which is narrow at the top and has a small balloon of glass at the bottom. It is filled with Mercury. 19 © Jnana Prabodhini Educational Resource Centre
  20. 20. Mercury is a liquid sparkling substance ( metal). It can be seen from distance, and does not stick to glass. It’s freezing point is minus thirty nine degree Celsius and boils at three hundred and fifty seven degree Celsius. This means -It can show temperature difference between -39°c to 350°c . It expands and contracts for small heat also. It’s expansion and contraction is uniformly. 20 © Jnana Prabodhini Educational Resource Centre
  21. 21. The base on which the thermometer is fixed has marks from 0°c to 100 °c. While marking this, the balloon full of Mercury is dipped in boiling water. Mercury expands and level of mercury in the tube increases. The level at which the Mercury is stable is marked as 100°c. 21 © Jnana Prabodhini Educational Resource Centre
  22. 22. When the balloon of thermometer is dipped in ice the level of Mercury in the tube decreases. The level at which it is stable is marked as 0°c. The distance between 0°c to 100 °c is divided into 100 equal part and are marked. One part is 1 °c. 22 © Jnana Prabodhini Educational Resource Centre
  23. 23. If a substance is heated , the increase in temperature is depend on following parts Duration of heat – More the duration more the increase in temperature. Volume of substance – If the volume of substance is less the increase in temperature is early. Format of substance – some items heated slowly and some heated fast. 23 © Jnana Prabodhini Educational Resource Centre
  24. 24. Different substances shows different increase in temperature if same amount of heat is provided. If we have to increase temperature of different substances of same volume with 1°c , the amount of heat is different. 24 © Jnana Prabodhini Educational Resource Centre
  25. 25. Heat required to increase the temperature of a substance by 1°c is called as calories of the substance. 25 © Jnana Prabodhini Educational Resource Centre
  26. 26. Heat required to increase temperature of 1 Kg substance by 1°c is called as specific heat of the substance. 26 © Jnana Prabodhini Educational Resource Centre
  27. 27. While making appliances which work in high temperature care should be taken for calories required and specific heat of substances. Example : Engine of a vehicle , Geyser, Heater, many more electric appliances. 27 © Jnana Prabodhini Educational Resource Centre
  28. 28. Heat Level is measured in Celsius and heat calories is measures in Kilo grams. 1 Kilo Calorie = 1000 Calories Heat required to increase temperature of 1 Kg. of water with 1°c is called as 1 kilo Calories. To increase temperature of 1 gram of water with 1°c is 1 Calorie. 28 © Jnana Prabodhini Educational Resource Centre
  29. 29. If cold water is mixed with hot water , hot water gives out heat and cold water receives heat till the temperature of all water becomes equal. When hot and cold items come in contact with each other there is give and take of heat. This is called as heat transformation. 29 © Jnana Prabodhini Educational Resource Centre
  30. 30. Heat Transformation Heat given by hot substance = Heat received by cold substance. Heat transformation is depend on following things Volume of substance Specific heat of the substance Temperature difference of the substance 30 © Jnana Prabodhini Educational Resource Centre
  31. 31. A device used to study the heat transfer and to count specific heat of substance is called as Calorimeter. 31 © Jnana Prabodhini Educational Resource Centre
  32. 32. Calorimeter is made up of copper vassal fixed in a wooden pot with wooden particles and other heat resistance material to fill the gap between two containers. The lid of the outer pot is made out of heat resistance material. The lid has two holes one for thermometer and other for stirrer to keep in copper vassal. 32 © Jnana Prabodhini Educational Resource Centre
  33. 33. The copper vassal of calorimeter is filled with hot / cold water. The substance of which specific heat is to be measured is put either hot or cold into the calorimeter. (Solid) The mixer is stir till the temperature of all the mixture becomes same. The before and after temperature is noted using the thermometer. Using proper formula Specific Heat of substance is calculated. 33 © Jnana Prabodhini Educational Resource Centre

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