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

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

SWBAT….. define the terms system and surroundings in

the context of a chemical reaction. identify the system and surroundings in a

thermochemical reaction. 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

thermochemical rtn Apply Hess’s law of heat summation in a

thermochemical equation.

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 ENDOTHERMICPROCESSES

COMPARE AND CONTRAST USING VENN DIAGRAM

Exothermic Process:o Heat is release to the surroundings (surroundings

warms up)o The system loses heat (system products cools

down)o q= negative

Endothermic Process:o Heat is absorbed from the surroundings

(surroundings cool down)o The system gains heat (system products warms

up)o q= positive

UNIT FOR MEASURING HEAT FLOW

Calorie (cal) : quantity of heat needed to raise the temperature of 1g of pure water to 10C. o 1 Calorie = 1 Kilocalorie = 1000 calorieso 20 Cal (dietary potential energy) = 20 Kcal (when

energy completely used up/released)

Joules (S.I. Unit of energy)o One Joule (1J) of heat is the energy needed to raise

the temperature of 1g of pure water to 0.23900Co Unit Conversion:o 1J = 0.2390 cal 4.184J = 1calo 1000J = 1kJ (kiloJoules)

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:o Mass of an objecto 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

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What is your level of understanding on:o System and surroundingso Endothermic and Exothermico Calorie/Kilocalorieo Heat Capacityo Specific Heat Capacity

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 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?