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Energy. Chap. 16. Definitions. Definitions. Energy. Energy is the ability to do work or produce heat. Definitions. Energy Heat. Heat is energy moving from one place to another. Heat = Energy. For us, these terms will be used synonymously. Definitions. Energy Heat Temperature.
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Energy Chap. 16
Definitions • Energy Energy is the ability to do work or produce heat
Definitions • Energy • Heat Heat is energy moving from one place to another
Heat = Energy For us, these terms will be used synonymously
Definitions • Energy • Heat • Temperature A measure of the kinetic energy of the particles in a substance
Definitions • Energy • Heat • Temperature • Endothermic A description of a process that absorbs heat
Definitions • Energy • Heat • Temperature • Endothermic • Exothermic A description of a process that gives off heat
Types of Energy • Kinetic Energy of motion
Types of Energy • Kinetic • Mechanical Moving objects
Types of Energy • Kinetic • Mechanical • Thermal Heat energy (moving particles)
Types of Energy • Kinetic • Potential Stored energy
Types of Energy • Kinetic • Potential • Gravitational Energy that can be released as gravity acts
Types of Energy • Kinetic • Potential • Gravitational • Chemical Energy stored in chemical bonds
Types of Energy • Kinetic • Potential • Radiant Energy in the form of light
Measuring Heat (q) • Units
Measuring Heat (q) • Units • joule SI unit of energy (work). Work done by applying one Newton force over one meter.
Measuring Heat (q) • Units • joule • calorie Energy required to heat one gram of water by 1° C.
Measuring Heat (q) • Units • joule • calorie • Calorie A nutritional calorie. 1 Cal = 1000 cal
Measuring Heat (q) • Units • joule • calorie • Calorie • kilocalorie Equivalent to calories
Measuring Heat (q) • Units • joule • calorie • Calorie • kilocalorie Equivalent to 1000 calories
Measuring Heat (q) • Units • joule • calorie • Calorie • kilocalorie • BTU Energy required to heat 1 lb. water by 1º F.
Heat Unit Conversions 1 cal = 4.184 J 1000 cal = 1 Cal = 1 kcal
Self Check – Ex. 1 A reaction produces 3800 J of heat. How many calories is this?
Self Check – Ex. 2 A can of soda contains 150 Calories. How many joules of energy is this?
Measuring Heat (q) • Units • Heat is related to temperature
Measuring Heat (q) • Units • Heat is related to temperature Temp. = 35º C Temp. = 65º C Beaker #1 Beaker #2 Which has more heat?
Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . .
Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Mass of material
Which beaker could melt more ice (which has more heat)? T2 = 85º C T1 = 85º C Beaker #1 Beaker #2
Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Mass of material • Type of material
Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Specific Heat Amount of heat required to raise the temperature of 1 gram of substance by 1º C
Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Specific Heat • Some material takes a lot of energy to raise its temperature
Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Specific Heat • Some material takes a lot of energy to raise its temperature • Some material takes less
Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Specific Heat • Some material takes a lot of energy to raise its temperature • Some material takes less • For water it’s 1 calorie/g ºC
Specific Heat Table SubstanceSpec. Heat (c) Water 4.184 J/g ºC Aluminum 0.89 J/g ºC Iron 0.45 J/g ºC Copper 0.387 J/g ºC Silver 0.24 J/g ºC Gold 0.129 J/g ºC Lead 0.l28 J/g ºC
Measuring Heat (q) • Units • Heat is related to temperature • Heat also depends on. . . • Specific Heat • Calculation q = m x c x∆T
Self Check – Ex. 3 How much heat must be applied to a 25 g chunk of iron to raise its temperature by 100ºC? (ciron = 0.45 J/g ºC)
Self Check – Ex. 4 How much heat must be applied to a 25 g sample of water to raise its temperature by 100ºC? (ciron = 4.18 J/g ºC)
Bond Energy • When bonds are broken energy is . This is endothermic
Bond Energy • When bonds are broken energy is required. (positive) This is endothermic
Bond Energy • When bonds are broken energy is required. (positive) • When bonds are formed energy is .
Bond Energy • When bonds are broken energy is required. (positive) • When bonds are formed energy is released. (negative) This is exothermic
Bond Energy • When bonds are broken energy is required. (positive) • When bonds are formed energy is released. (negative) • The sum of the bond energies gives an estimate of the reaction energy
Bond Energy • When bonds are broken energy is required. (positive) • When bonds are formed energy is released. (negative) • The sum of the bond energies gives an estimate of the reaction energy • Positive values = endothermic
Bond Energy • When bonds are broken energy is required. (positive) • When bonds are formed energy is released. (negative) • The sum of the bond energies gives an estimate of the reaction energy • Positive values = endothermic • Negative values = exothermic
Self Check – Ex. 5 Draw Lewis structures for each substance and calculate the energy for the reaction below. 2CO + O2 2CO2