1 Thermochemistry.pdf

Thermochemistry Zeroth & First Law of Thermodynamics Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Lesson Objectives 1. Explain the first law of thermodynamics. 2. Define internal energy, work and heat. 3. State the relati...

Thermochemistry Zeroth & First Law of Thermodynamics Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Lesson Objectives 1. Explain the first law of thermodynamics. 2. Define internal energy, work and heat. 3. State the relationship between internal energy, work and heat. Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus What is thermodynamics? Study of energy transfer and energy transformation SYSTEM vs. SURROUNDINGS Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus SYSTEM Specific part of the universe being studied. Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus SURROUNDINGS Everything else that can be affected by the system Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus UNIVERSE Consists of system and surroundings Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus What is thermodynamics? Study of energy transfer and energy transformation Windmill: Kinetic Energy  Rotational Energy  Mechanical Energy  Electrical Energy Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus What is thermodynamics? Study of energy transfer and energy transformation Flashlight: Chemical Energy  Electrical Energy  Light Energy Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus  thermodynamics Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus  thermodynamics TEMPERATURE Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Temperature Is the measure of how much kinetic energy is present in a system. Indicator of thermal equilibrium. Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Temperature Is the measure of how much kinetic energy is present in a system. Indicator of thermal equilibrium. BALANCE Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Thermal Equilibrium Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Zeroth Law of Thermodynamics When system A is in thermal equilibrium with system B and separately in thermal equilibrium with system C then system B and system C, will also be in thermal equilibrium with each other. Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Zeroth Law of Thermodynamics Systems that are in thermal equilibrium exist at the same temperature. Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus First Law of Thermodynamics Law of Conservation of Energy “Energy can neither be created nor destroyed. It can only be transferred or converted from one form to another.” Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus First Law of Thermodynamics Kinetic and Potential Energy Internal Energy, E Work, w Heat, q Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus First Law of Thermodynamics Internal Energy, E Sum of all kinetic and potential energy of the system. Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus First Law of Thermodynamics (Equation 1) 1. Number 2.Unit + means net gain of energy by the system 3.Sign (+ or – ) – means net loss of energy by the system Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus First Law of Thermodynamics Work, w Energy transferred when an object is moved by force through a distance. Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus First Law of Thermodynamics Heat, q Energy transferred between the system and surroundings because of temperature difference only. Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Internal Energy ( ) Work ( ) Heat ( ) Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus  = + (Equation 2) = + First Law of Thermodynamics Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus First Law of Thermodynamics Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Sample Problem # 1 A system loses 354 J of heat and at the same time it does 94 J of work to its surroundings. What is the change in internal energy of the system in the same unit? Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Sample Problem # 1 A system and at the same time it. What is the of the system in the same unit? Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Sample Problem # 1 Step 1: Determine the signs for quantitative values. Step 2: Use the formula for internal energy = + Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Sample Problem # 2 Calculate the work if the system has a net change of 0.500 kJ of internal energy after it gained 143 J of heat. What does the sign of work indicate about its direction? Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Sample Problem # 2 Calculate the work if the system has a of internal energy after it. What does the sign of work indicate about its direction? Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Sample Problem # 2 Step 1: Determine the signs for quantitative values. Step 2: Use the formula for internal energy = + = + = Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Sample Problem # 3 Calculate the ΔE for the following cases: a) A system absorbs 105 kJ of heat from its surroundings while doing 29 kJ work on the surroundings. (5 pts.) 76 kJ b) The system releases 57.5 kJ of heat while doing 22.5 kJ of work on the surroundings. (5 pts.) -80 kJ Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus Lesson Objectives 1. Explain the first law of thermodynamics. 2. Define internal energy, work and heat. 3. State the relationship between internal energy, work and heat. Chemistry 02 | G10 Graviton | G10 Gluon Philippine Science High School – Central Visayas Campus