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49 Cards in this Set
- Front
- Back
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Thermodynamics
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The science of heat, work, & transformations of one to the other
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Energy
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The capacity to do work
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Symbol for Energy
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E
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Kinetic energy
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The energy that something has because it is moving
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Potential energy
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The energy something has as a result of its position and some force that is capable of changing that position
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1 cal = ___ J
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1 cal = _4.184_ J
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Title of the First Law of Thermodynamics
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The Law of Conservation
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The Law of Conservation states:
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Energy can neither be created or destroyed - the total energy in the universe is constant
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Work on an object transfers _____ to that object
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Work on an object transfers _energy_ to that object
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Thermal Equilibrium
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Common Temperature
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System, in thermodynamics
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Region of primary concern
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Surroundings, in thermodynamics
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Everything that can exchange heat with the system
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Internal energy of a system
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The sum of the individual energies (kinetic & potential) of all nano-scale particles in the system
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ΔE =
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q + w (heat + work)
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Energy transfers can occur by either _____ or ______
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Energy transfers can occur by either _heating_ or _work_
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Heat Capacity
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The quantity of energy required to increase the temperature of that sample by one degree
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Specific Heat Capacity (Specific Heat)
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The quantity of energy required to increase the temperature of one gram of a substance by one degree celsius
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Symbol for specific heat
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c
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Formula for specific heat (with no work being done)
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c = q / (m * ΔT)
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Molar heat capacity
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Cm: The amount of energy that must be transferred to increase the temperature of one mole of a substance by 1 °C
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Endothermic
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energy is transferred into the system
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Exothermic
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energy is transferred out of the system
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formula for w (work):
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w = - ( F * d )
work = - (force * distance) |
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enthalpy change
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The quantity of energy transferred into a system at constant pressure; ΔH
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ΔH =
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ΔE + PΔV
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Change of State / Phase Change
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A physical process in which one state of matter is transformed into another
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Temperature _________ during a phase change
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Temperature _remains constant_ during a phase change
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Enthalpy of Fusion
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The quantity of thermal energy that must be transferred to a solid to cause it to melt
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Enthalpy of Vaporization
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The quantity of thermal energy that must be transferred to convert a liquid to a gas (vapor)
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State functions
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changes in a system that are independent of the sequence of events by which change occurs
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Thermochemical Expression
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a balanced chemical equation together with the corresponding value of the enthalpy change
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ΔH°
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Standard Enthalpy Change
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Standard Enthalpy Change
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The enthalpy change at standard temperature & pressure
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Bond Enthalpy (Energy)
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The enthalpy change that occurs when two bonded atoms in a gas-phase molecule are separated completely
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Bond breaking is always ___thermic
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Bond breaking is always _endo_thermic
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Bond making is ___thermic
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Bond making is _exo_thermic
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Two ways for an exothermic reaction to occur:
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1. weaker bonds in reactant, stronger bonds in product
2. bonds of equal strength in reactants and product, more bonds in product |
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Calorimeter
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a device that measures heat transfer
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Formula for measuring energy change in a bomb calorimeter
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(ΔE transferred to calorimiter + ΔE transferred to water) per mol of reactant
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Hess' Law
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If the equation for a reaction is the sum of the equations for two or more other reactions, then ΔH° for the first reaction must be the sum of ΔH° values of the other reactions
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Standard Molar Enthalpy of Formation
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Hf° - The standard enthalpy change for formation of *one* mole of a compound (*product*) from its *elements* in their standard states.
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Formula for the standard enthalpy change of a reaction:
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ΔH° =
Σ{(moles of product) * ΔHf°(product)} - Σ{(moles of reactant) * ΔHf°(reactant)} |
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Chemical Fuel
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Any substance that will react exothermically with oxygen (and is available at reasonable cost and in reasonable quantity)
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Fuel value
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The quantity of energy released when 1 g of fuel is burned
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Energy density
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The amount of energy released per unit volume of fuel
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General formula for a carbohydrate
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Cx(H₂O)y
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Caloric value of fats, proteins & carbohydrates
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fats: 9
proteins: 4 carbohydrates: 4 |
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Caloric value
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Standard energy of enthalpy for 1 g of food
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Basal Metabolic Rate (BMR):
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The minimum energy intake required to maintain a body that is awake and at rest
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