Think pair share
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Think-pair-share. Respond to at least One question below using the organizer provided. Be prepared to share your thoughts QUESTIONS: 1. Describe what happens to a rat that has been eaten by a python. 2. What is the function of the digestive system? What are calories?

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Think pair share

Think-pair-share

  • Respond to at least One question below using the organizer provided. Be prepared to share your thoughts

  • QUESTIONS:

  • 1. Describe what happens to a rat that has been eaten by a python.

  • 2. What is the function of the digestive system? What are calories?

  • 3.How can you measure the calories contained in food?

  • 4. What do you think happens if a person eats more calories than their body needs?


Thermochemistry

THERMOCHEMISTRY

http://ca.pbslearningmedia.org/resource/nvsn6.sci.bio.fuel/food-is-fuel/


Swbat

SWBAT…..

  • define the terms system and surroundings in the context of a chemical reaction.

  • identify the system and surroundings in a thermochemicalreaction.

  • describe how heat is transferred in endothermic and exothermic reactions

  • Calculate specific heat of a substance in calories and joules

  • Calculate enthalpy changes in a thermochemicalrtn

  • Apply Hess’s law of heat summation in a thermochemical equation.


Heat and work

Heat and Work:

  • TERMINOLOGIES:

  • Thermochemistry: studies energy changes in chemical reactions and changes of state.

  • Heat (q): is the transfer of energy from one object to another because of temperature difference (warmer to cooler object)

  • System: part of the universe being studied or focus of attention (e.g. reactants and products of a reaction)

  • Surroundings: the immediate vicinity of the system (e.g. container, space, universe, e.t.c.)

  • Law of conservation of energy: states that energy is neither created nor destroyed in any chemical or physical process.


Exothermic and endothermic processes

Exothermic and EndothermicProcesses

  • COMPARE AND CONTRAST USING VENN DIAGRAM

  • Exothermic Process:

    • Heat is release to the surroundings (surroundings warms up)

    • The system loses heat (system products cools down)

    • q= negative

  • Endothermic Process:

    • Heat is absorbed from the surroundings (surroundings cool down)

    • The system gains heat (system products warms up)

    • q= positive


Unit for measuring heat flow

Unit for Measuring Heat Flow

  • Calorie (cal) : quantity of heat needed to raise the temperature of 1g of pure water to 10C.

    • 1 Calorie = 1 Kilocalorie = 1000 calories

    • 20 Cal (dietary potential energy) = 20 Kcal (when energy completely used up/released)

  • Joules (S.I. Unit of energy)

    • One Joule (1J) of heat is the energy needed to raise the temperature of 1g of pure water to 0.23900C

    • Unit Conversion:

    • 1J = 0.2390 cal 4.184J = 1cal

    • 1000J = 1kJ (kiloJoules)


Heat capacity

Heat Capacity

  • Heat Capacity: amount of heat needed to increase the temperature of an object to exactly 10C. ( Unit for heat capacity = J/0C)

  • Heat capacity depends on:

    • Mass of an object

    • Chemical composition of the object

  • Specific Heat Capacity (C): is the amount of heat it takes to raise the temperature of 1g of substance (object) to 10C. (Unit for Specific Heat = J/(g.0C) or J/(kg.0C) or kcal/(kg.0C) ). Remember: 1000g = 1Kg


Check for understanding

Check for understanding

  • Thumbs Up

  • Thumbs Down

  • Thumbs side

  • What is your level of understanding on:

    • System and surroundings

    • Endothermic and Exothermic

    • Calorie/Kilocalorie

    • Heat Capacity

    • Specific Heat Capacity


Calculating specific heat capacity c of a substance

Calculating Specific Heat/Capacity(C) of a Substance

  • Formula for calculating Specific Heat

  • Unit for Specific Heat

  • Specific Heats of some common substances (see PHC: table 17.1, page 508)


Heat math problems

Heat Math problems

  • When 435J of heat is added to 3.4g of olive oil at 210C, the temperature increases to 850C. What is the specific heat of the olive oil?

  • How much heat is required to raise the temperature of 250.0g of mercury 520C?

  • An orange contains 445kJ of energy. What mass of water could the same amount of energy raise from 25.00C to the boiling point?


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