 The ability to do work  The ability to transfer heat Two types: Kinetic and Potential

 Energy do to motion or action  electromagnetic waves (light), heat, motion, electrical current,  A moving truck has the ability to flatten you - do work on you!

 Energy due to position (gravitational or electrical) or chemical bonds  Stored energy  Position: boulder at the top of the hill, water behind a dam, stick of plastique  Chemical: tank of gas, hamburger

Death is very likely the single best invention of Life. It is Life's change agent. It clears out the old to make way for the new. Right now the new is you, but someday not too long from now, you will gradually become the old and be cleared away. Sorry to be so dramatic, but it is quite true. Your time is limited, so don't waste it living someone else's life. Don't be trapped by dogma — which is living with the results of other people's thinking. Don't let the noise of others' opinions drown out your own inner voice. And most important, have the courage to follow your heart and intuition. They somehow already know what you truly want to become. Everything else is secondary.

 Energy can neither be created nor destroyed, but you may change from one form to another

 When energy is changed from one form to another, some of the energy is degraded to a lower-quality, more dispersed energy form No reaction can be 100% efficient All reactions lose energy (usually as heat) Systems only go spontaneously in the direction of decreasing order (increasing entropy) heat always flows from hot to cold

 Entropy is the amount of disorder in a system  Entropy always increases over time (in the absence of an input of outside energy)  example. cleaning up your room

 There are two units which are commonly used:  Calories (c): amount of energy it takes to raise one gram of water one degree Celsius Calories in food (C) = kilocalories(kcal) = 1000 calories  Joules (J): 4.18 Joules = 1 calorie

 Heat is the amount of kinetic energy of the atoms  Temperature measures the average speed of the atoms

 Homework pages 8-9

J Deutsch

AIM Heating and Cooling Curves DO NOW Page 14

 Exothermic - Potential energy decreases Releases energy  H, change in heat, is negative Energy is on the right  2H 2 + O 2  2H 2 O + energy  Endothermic - Potential energy increases Absorbs energy  H, change in heat, is positive Energy is on the left  2H 2 O + energy  2H 2 + O 2 22

A hot pack contains chemicals that can be activated to produce heat. A cold pack contains chemicals that feel cold when activated. 1. Based on energy flow, state the type of chemical change that occurs in a hot pack. Exothermic 2. A cold pack is placed on an injured leg. Indicate the direction of the flow of energy between the leg and the cold pack. From the leg to the cold pack (Hot to Cold) 3. What is the Law of Conservation of Energy? Describe how the Law of Conservation of Energy applies to the chemical reaction that occurs in the hot pack. Energy cannot be created nor destroyed. It can only be changed from one form to another. The heat produced in the hot pack was stored in the chemical bonds. 23

26 Potential energy changes, so temperature doesn’t Boiling Point Melting Point

28  AB solid warms up (KE  /PE constant)

30  AB solid warms up (KE  /PE constant)  BC solid melts (KE constant/PE  )

32  AB solid warms up (KE  /PE constant)  BC solid melts (KE constant/PE  )  CD liquid warms up (KE  /PE constant)

34  AB solid warms up (KE  /PE constant)  BC solid melts (KE constant/PE  )  CD liquid warms up (KE  /PE constant)  DE liquid boils (KE constant/PE  )

36  AB solid warms up (KE  /PE constant)  BC solid melts (KE constant/PE  )  CD liquid warms up (KE  /PE constant)  DE liquid boils (KE constant/PE  )  EF gas warms (KE  /PE constant)

J Deutsch As ice melts at standard pressure, its temperature remains at 0°C until it has completely melted. Its potential energy (1) decreases (2) increases (3) remains the same

J Deutsch A sample of water is heated from a liquid at 40°C to a gas at 110°C. The graph of the heating curve is shown in your answer booklet. a On the heating curve diagram provided in your answer booklet, label each of the following regions: Liquid, onlyGas, onlyPhase change Liquid Only Gas Only Phase change

J Deutsch b For section QR of the graph, state what is happening to the water molecules as heat is added. c For section RS of the graph, state what is happening to the water molecules as heat is added. They move faster, their temperature increases. Their intermolecular bonds are breaking, their potential energy is increasing.

J Deutsch What is the melting point of this substance? (1) 30°C(3) 90°C (2) 55°C (4) 120°C

How do we calculate amount of heat,(Q), if we are not given a graphic?

 Q = mC  T  Q = mH f  Q = mH v  Have to figure out which one to use for a given problem.  Depends which section of heating curve.  Look for hints in the problem.

Calculating Heat Transferred Q = mC  T Simple system: Pure substance in a single phase. To calculate heat gained or lost, use: Q = amount of heat transferred Q = amount of heat transferred m = mass of substance m = mass of substance C = specific heat capacity of the substance (Table B). C = specific heat capacity of the substance (Table B).  T = temperature change = T final – T initial  T = temperature change = T final – T initial

 Temperature changed  Temperature increased  Temperature decreased  Initial / Start temperature  Final temperature  Ending temperature  From ____ to ____  Water

Amount of energy required to convert 1 gram of a pure substance from the solid to the liquid phase at the melting point. Heat of Fusion

Q = mH f Use this equation to calculate energy changes for phase changes between ice & liquid water at 0  C.

 Ice  Freezing  Melting  At 0  C (for H 2 O)  At constant temperature

Amount of energy required to convert 1 gram of a pure substance from the liquid to the gas phase at the boiling point. Heat of Vaporization

Q = mH v Use this equation to calculate energy changes for phase changes between steam & liquid water at 100  C.

 Steam  Boiling  Condensation  At 100  C (for H 2 O)  At constant temperature