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Chapter 3

Chapter 3. Specific Heat Part 1 and Part 2. Specific Heat. Different substances require different amounts of heat to change their temperature. In general the specific heat of a substance indicates how hard something is to heat up or cool down.

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Chapter 3

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  1. Chapter 3 Specific Heat Part 1 and Part 2

  2. Specific Heat • Different substances require different amounts of heat to change their temperature. • In general the specific heat of a substance indicates how hard something is to heat up or cool down. • Scientifically speaking the specific heat is the amount of heat required to change the temperature of 1 gram of a substance by 1ºC.

  3. Which substance is the easiest to heat up or cool down?

  4. → • Which substance is the easiest to heat up or cool down?

  5. Which substance is the hardest to heat up or cool down?

  6. → • Which substance is the hardest to heat up or cool down?

  7. → • Which substance is the hardest to heat up or cool down? • How might we observe the high specific heat of water?

  8. “Flying Freddie Spooner” 2014 Tri-Valley Cannonball Champion

  9. → • Scientific interpretation of the specific heat of water.

  10. The specific heat of water • The specific heat of water is 4.184 J/g•ºC. • To simplify our discussion we will round this to 4 J/g•ºC.

  11. The specific heat of water • If we have one gram of water at 25ºC and we add 4J of energy to it what will the temperature be? • Answer: 26ºC

  12. The specific heat of water • If we have two grams of water at 30ºC and we remove 16J of energy from it what will the temperature be? • Answer 28ºC

  13. The specific heat of water • The high specific heat of water has many implications to our everyday lives.

  14. Importance of Water’s High Specific Heat • Maintenance of Body Temperature

  15. Importance of Water’s High Specific Heat • Heat Storage on a Larger Scale.

  16. Importance of Water’s High Specific Heat • Temperature fluctuations that permit life.

  17. Homework • Worksheet Chapter 3 – 2 (due tomorrow) • Study Guide Chapter 3 (due Friday)

  18. How Much Heat? • I want to heat some water. • What do I need to know in order to determine the amount of heat required? • Mass of water. • Temperature Change • Specific Heat of Water

  19. H = m ∆T Cp Heat = (mass) x (change in temperature) x (specific heat)

  20. Kilojoules • kilo (k) = 1000 • kJ = 1000 J • 4.08 kJ = 4080 J

  21. How much heat is necessary to heat 258g of water from 25.0ºC to 100.0ºC? (258g)(75.0ºC)(4.184J/gºC) = 80,960.4J = 81,000J = 81.0 kJ

  22. How much heat must be removed to cool 1058g of copper from 325.0ºC to 18.0ºC? (1058g)(307.0ºC)(0.385J/gºC) = 125,050J = 125,000J = 125 kJ

  23. How “much” water do I have? 52.8 ml = 52.8 cm3 or 52.8 g

  24. The mass of an unknown metal is 14.9 g. It is heated to 100.0C and dropped into 75.0 mL of water at 20.0C. The final temperature of the system is 28.5C. What is the specific heat of the metal?

  25. The mass of unknown metal is 17.19 g. It is heated to 100.00C and dropped into 25.00 mL of water at 24.50C. The final temperature of the system is 30.05C. What is the specific heat of the metal? q 580.53J J = C of metal = = 0.48279 p D ) m x T o o (17.19g ( 69.95 C) g C Heat gained by the water = Heat lost by the metal m ∆T Cp = m ∆T Cp (25.00g)(5.55°C)(4.184 J/g C) = (17.19g)(69.95°C)(x) Cp = 0.4828 J/g · °C

  26. Homework • Worksheet Chapter 3 – 3 (due tomorrow) • Study Guide Chapter 3 (due Thursday)

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