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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?

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Think-pair-share

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  1. 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?

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

  3. 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.

  4. 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.

  5. 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

  6. 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)

  7. 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

  8. 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

  9. 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)

  10. 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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