1. Some Like it Hot and Some Sweat when the Heat is On!!! https://www.youtube.com/watch?v=vqDbMEdLiCs

2. First Law of Thermodynamics All energy lost by one system must be gained by the surroundings (another system) System: A group of interacting objects and effects that are selected for investigation. Surroundings: Everything else except the system.

3. Types of Systems Open System Matter and energy can be exchanged with the surroundings Ex. An open coffee cup (w/o lid)

4. Types of Systems Closed System: Only energy is allowed to be exchanged with the surroundings Ex. A coffee cup w/ lid

5. Types of Systems Isolated System: Neither matter nor energy can be exchanged with surroundings Ex. Insulated Thermos

6. Second Law of Thermodynamics States energy (heat) spontaneously flows from higher temperature to lower temperature until it reaches thermal equilibrium. A condition where the temperatures are the same and heat no longer flows Hot Coffee Heat Flow

7. Specific Heat The quantity of energy it takes per gram of a certain material to raise the temperature by one degree Celsius. An intensive property. Symbol: c p Units: J/g· ℃

8. Examples of Specific Heats 1. Water4.184 J/g· ℃ 2. Air1.006 J/g· ℃ 3. Aluminum 0.900 J/g· ℃ 4. Gold 0.129 J/g· ℃ 5. Steel0.470 J/g· ℃

9. Insulator vs. Conductor Substances with lower specific heat values are better conductors of heat. Conductor – a material that allows the flow of heat easily. (metals) Substances with higher specific heat values are poor conductors of heat Insulator – a material that resists the flow of heat (Styrofoam, rubber)

10. Heat Equation Used to calculate how much energy it takes to make a temperature change in a mass of material E = m ·c p ·(T 2 -T 1 ) E = energy m = mass c p = specific heat T 2 = final temperature T 1 = starting temperature

11. Example of Using Heat Equation 1. Calculate the amount of energy required to heat 15.5 g of water from 17 ℃ to 25 ℃.

12. Another example – Let’s switch it up! 2. A scientist inputs 27,500 J of thermal energy into a sample of steel. The temperature increases from 15 ℃ to 75 ℃. What is the mass of the steel?

13. Review Problem #1 A 62.5-g piece of copper absorbs 6,140 J of energy when heated by a Bunsen burner. If the temperature of the copper increases from 21 °C to 310 °C, what is the specific heat of the metal?

14. Review Problem #2 A 25.5 g sample of precious gold has an initial temperature of 15 °C. A flame transfers 378 J of thermal energy to the gold. What is the final temperature of the gold? (c p gold = 0.129 J/g· ℃ )

15. Finding Specific Heat through Energy Transfer: Remember: The heat energy lost by one system is always gained by its surroundings!

16. Finding Specific Heat Problem: A hot piece of metal is dropped into 150-g of water with a starting temperature of 21 °C. The temperature of the water increased to 30 °C. 1. How much energy was needed to increase the temperature of the water?

17. Where did the energy come from?

18. 2. If the metal has a mass of 47 g and a starting temperature of 200 °C, what is the specific heat of the metal? Assume – all energy lost by metal = all energy gained by water Assume – final temps of both are equal (thermal equilibrium)