# Shared Flashcard Set

## Details

Chem Test 2; Ch 5
Chapter 5
58
Chemistry
10/08/2012

Term
 Thermochemistry
Definition
 the study of the relationships between chemical reactions and energy changes.
Term
 Work
Definition
 Energy used to cause an object that has mass to move against a force.
Term
 Formula of the relationship of work and force and distance
Definition
 w = F  dw-workf-forced-distance
Term
 Heat
Definition
 Energy transferred from a hotter object to a colder one.
Term
 Kinetic Energy
Definition
 energy associated the motion of an object.
Term
 Kinetic Energy Formula
Definition
 Ek = 1/2(m)(v^2)
Term
 Potential Energy
Definition
 energy associated with the position or composition of an object
Term
 The SI unit of energy is the?
Definition
 Joule (J)
Term
 1J =
Definition
 1 (kg)(m^3)/s^2
Term
 The calorie is?
Definition
 (cal) the amount of energy required to raise the temperature of one gram of water 1oC
Term
 Relationship of cal and J
Definition
 1 cal = 4.184 J
Term
 First Law of Thermodynamics Law of Conservation of Energy?
Definition
 Energy is neither created nor destroyed
Term
 Energy can be transferred between ?
Definition
 a system and the surroundings.
Term
 In a Chemical reaction the system and surroundings are?
Definition
 system-reactants and products, can beOpen, closed, or isolatedSurroundings-container and everything else
Term
 Internal Energy symbol?
Definition
 E
Term
 Internal Energy def>
Definition
 the sum of all kinetic and potential energies of all its components.
Term
 The change in internal energy is?
Definition
 &E = Efinal − Einitial&= triangle that means change
Term
 The change in internal energy in a chemical reaction formula?
Definition
 &E = E products − E reactants
Term
 Energy can be exchanged through ?
Definition
 heat and work
Term
 Relationship of energy to heat and work?
Definition
 &E = q + w
Term
 WORK A system absorbs 125 J of heat from the surroundings and does 62 J of work on the surroundings. Calculate the change in internal energy (E) in J.
Definition
 +63 J
Term
 State function
Definition
 depends only on the present state of the system, not on the path by which the system arrived at that state.
Term
 Internal energy is/ is not a state function?
Definition
 IS
Term
 q and q are/ are not state functions?
Definition
 NOT
Term
 Work formula
Definition
 w = −P&V
Term
 &V formula
Definition
 &V= V final – V initial
Term
 If V increases then?
Definition
 w= is neg and work is done By the system ONTO the surroundings
Term
 Enthalpy def
Definition
 H- the heat transferred between the system and surroundings during a chemical reaction carried out under constant pressure.
Term
 H formula
Definition
 = E+PV
Term
 &H formula
Definition
 =&E+P&V
Term
 &H formula same as?
Definition
 q,p
Term
 Endothermic
Definition
 heat is absorbed from the surroundings by the system
Term
 Exothermic
Definition
 heat is released by the system to the surroundings
Term
 &H formula
Definition
 = &H,rxn= H products- H reactants
Term
 Enthalpy is an _____ property
Definition
 Extensive meaning it differs with the states of the substances
Term
 H for any reaction written in reverse will have the same magnitude of heat associated with it, but ?
Definition
 opposite sign
Term
 WORK 2 H2(g) + O2(g) → 2 H2O(g) ∆H = - 483.6 kJ What is ∆H for 2 H2O(g) → 2 H2(g) + O2(g)
Definition
 ∆H = + 483.6 kJ
Term
 WORK2 H2(g) + O2(g) → 2 H2O(g) ∆H = - 483.6 kJ What is ∆H for 4 H2O(g) → 4 H2(g) + 2 O2(g)
Definition
 ∆H = + 967.2 kJ
Term
 WORK2 H2(g) + O2(g) → 2 H2O(g) ∆H = - 483.6 kJ What is ∆H for 3 H2(g) + 3/2 O2(g) → 3 H2O(g)
Definition
 ∆H = - 725.4 kJ
Term
 specific heat def?
Definition
 C,s- the amount of energy required to raise the temperature of 1 g of a substance by 1 K (1C).
Term
 Molar heat capacity def?
Definition
 C,m- is the heat capacity of 1 mole of a substance.
Term
 Specific heat formula
Definition
 = heat transfer/ (mass)(change in temp)
Term
 q=
Definition
 q = Cs x m x &T
Term
 WORKHow much heat (kJ) is needed to warm 325 g of water from 24 oC to 75 oC. The specific heat (Cs) of water is 4.18 J/g-K?
Definition
 69 kJ
Term
 WORKHow much heat (kJ) is needed to warm 325 g of water from 24 oC to 75 oC. The specific heat (Cs) of water is 4.18 J/g-K? Answer: 69 kJb. What is the molar heat capacity of water (Cm)?
Definition
 75.3 J/mol-K
Term
 q solution =
Definition
 (specific heat of solution) x (grams of solution) x ∆T
Term
 WORKWhen 25.0 ml of 0.450 M AgNO3 and 33.0 ml of 0.341 M HCl are mixed in a constant-pressure calorimeter, the temperature of the mixture increases from 21.42 oC to 22.31 oC. Calculate H of the reaction in kJ/mol AgNO3,assuming the mixture has a density of 1.00 g/ml and that its specific heat is 4.18 J/g oC.
Definition
 -19 kJ/mol
Term
 Constant-Volume Calorimetry aka?
Definition
 Bomb Calorimetry
Term
 Formula of Bomb Calorimety?
Definition
 q reaction = - C,cal x ∆T
Term
 WORKA 1.146 g sample of lactic acid (HC3H5O3)is burned in a calorimeter whose heat capacityis 4.812 kJ/°C. The temperature increases from 23.07°C to 26.12°C.Calculate the heat of combustion of lactic acid per gram.
Definition
 -12.8 kJ/g
Term
 Hess’s law def
Definition
 If a reaction is carried out in a series of steps, H for the overall reaction is the sum of the enthalpy changes for the individual steps.
Term
 WORKCalculate H for the overall reaction 2 C(s) + H2(g) C2H2(g)given the following chemical equations and their respective enthalpy changes:See page 182 for reactions
Definition
Term
 Standard Enthalpy of formation
Definition
 &Hof), is the enthalpy change for the formation of 1 mol of compound from its elements, with all substances in their standard states (appendix C).
Term
 Standard State is?
Definition
 at 1 atm and 25 oC (298K).
Term
 &Hof of any element in its most stable form is
Definition
 0
Term
 WORKFor which of the following reactions at 25°C would the enthalpy change represent a standard enthalpy of formation? For each that does not, what changes would need to be made to make it an equation whose H is an enthalpy of formation?See page 184
Definition
 see page 184
Term
 &H,rxn =
Definition
 = n&Hf (products) - m&Hf reactants
Term
 WORK Calculate &Horxn for C3H8(g) + O2(g) → CO2(g) + H2O(l) Given Hof C3H8(g) = -103.85 kJ/mol Hof CO2(g) = -393.5 kJ/mol Hof H2O(l) = -285.8 kJ/mol
Definition
 -2.220 x 103 kJ
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