Chem Final Exam Review

Chem Final Exam Review - CHEM142/152 Final Exam Review The...

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CHEM142/152 Final Exam Review The final exam is Thursday morning, 9AM - noon in Chemistry 402.
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Chapter 14 - Kinetics Important equations: [A] = [A] 0 e -kt Integrated 1st-order rate law ln[A] = ln[A] 0 - kt Same equation, different form t 1/2 = ln(2) / k Half-life of 1st-order rxns 1/[A] = 1/[A] 0 + 2 kt Integrated 2nd-order rate law t 1/2 = 1/ k [A] 0 Half-life of 2nd-order rxns
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A couple more… k = A e -E /RT Arrhenius Equation ln k = ln A - E a / RT Same eqn, different form ln k 2 / k 1 = -E a /R (1/T 2 - 1/T 1 ) T-dependence of k
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Important terms k - the rate constant. Must be in correct units to give the rate units of M/s. Order - the power to which each concentration is raised, for example the rate = k [C 2 H 6 ] 2 [HIO 3 ] is second-order with respect to ethane and first- order in iodic acid. The overall reaction is the sum of the individual reactant orders. This reaction is third-order. Half-life - the time required to reduce an initial concentration by 50%. Elementary step - a direct collision of two (or more) atoms (or molecules) or the spontaneous decomposition of a single atom or molecule. Several elementary steps can be combined to form a reaction mechanism. Molecularity - the number of molecules involved in an elementary step. Most reactions are unimolecular or bimolecular. Rarely they are termolecular.
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More terms… Intermediate - any chemical species which is formed in an elementary step then completely consumed in a subsequent step. Chain reaction - any reaction the proceeds via several elementary steps. There are three stages: Initiation , Propagation , and Termination Rate-determining step - the slowest step in a reaction mechanism Activation energy - symbol E a , the energy required in the collision of two reactants in order to form products Catalyst - any chemical species or enzyme that acts in lower the activation energy of an elementary step. May be homogeneous or heterogeneous. In effect, a catalyst increases the rate of a reaction. Inhibitor - the opposite of a catalyst. Acts to slow the rate of a reaction.
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2NO + O 2 --> 2 NO 2 rate = k obs [NO] 2 [O 2 ] NO + NO <--> N 2 O 2 ( fast equil) N 2 O 2 + O 2 --> 2 NO 2 (slow) Find k obs in terms if k 1 , k -1 , and k 2
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Phases and Transitions Important equations: P vap = C e -∆H(vap) / RT The temperature dependence of vapor pressure P vap = x 1 P 1 0 Raoult’s Law for an ideal solution ( x is mole fraction) T b = imK b Boiling point elevation ( m is molality) T f = - imK f Freezing point depression ( m is molality) ∏ = icRT Osmotic pressure (c is in molarity)
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Concepts, terms… Vapor pressure - the pressure over a liquid in a sealed container at equilibrium Boiling point - the temperature at which the vapor pressure of a liquid equals the external pressure Melting point - the temperature at which a solid and liquid are at equilibrium at a given pressure
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- when all three phases are in equilibrium Critical point - the point beyond which there is no
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This note was uploaded on 04/07/2008 for the course CHEM 152 taught by Professor Metcalf during the Spring '07 term at UVA.

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Chem Final Exam Review - CHEM142/152 Final Exam Review The...

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