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16 Cards in this Set
- Front
- Back
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Kinetics
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- Study of reaction rates
- Tells nothing about the spontaneity of a reaction (nothing about thermodynamics, like G, H, and S) |
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Examples of Kinetic Things
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- Rate, how fast/slow, rate law, rate constant k, catalyst, activation energy, velocity, speed, K = Ae^(-Ea/RT)
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Examples of Thermodynamic Things
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- q = mcΔT
- q = n*ΔH - ΔH, ΔS, ΔG - c, C - Keq, Ka, Kb, Kw, Ksp, Kp, Kc - Q, Qsp, stability |
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Elementary Steps
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- Individual steps of a reaction mechanism
- Don't assume something is an elementary step unless told or given a reaction mechanism (meaning you can't make a rate law) |
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Intermediates
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- Not isolatable but can be detected
- Not present at end of a reaction |
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Rate Determining Step
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- SLOW STEP
- Gives the overall reaction rate, as a reaction can't go any faster than it's slowest step |
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What is a rate?
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- Change in something over time
- Reactants are NEGATIVE - Products are POSITIVE aA + bB --> cC + dD Reactant: -(1/a)*[ΔA]/Δt Product: +(1/c)*[ΔC]/Δt |
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What is required for a reaction to actually occur?
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- Reactants must meet
- Reactants must be in correct orientation - Must be enough energy |
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Activation Energy
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- Minimum energy required of reactant molecules during a molecular collision in order for the reaction to proceed to products
- If not enough of this, no rxn |
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What affects reaction rates?
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- Activation energy: the lower, the faster
- Greater [reactants], faster the rxn - Higher temperatures, faster rxn |
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Catalyst
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- Short cut
- Makes reaction go faster by changing KINETIC things, like activation energy. - Remains unchanged at the end of the rxn and is regenerated |
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Rate Law
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- Only gotten if they tell us its an elementary step like a slow step (RDS)
- Equation expresses rate at which reactant disappears - So we're concerned with REACTANTS.. determined experimentally of course - Rate = k[A]^x*[B]^y |
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How do we find the Rate Law?
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- Pick experiments where what you want changes, like [A], and where the others are constant [B], [C]
- What happens to the rate? - If it doubles but rate is unaffected, it's to the 0 power |
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Units of Rate Law
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1/s*M²
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Rate Constant (k) Units
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1/s
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Arrhenius Equation
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k = Ae^(-Ea/RT)
- Adding a catalyst or increasing temperature affects rate |
