Unit 3.5 Chemical kinetics Flashcards by Shirou Aizen

To be soon

Hopefully no test?
There’s a test coming….

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It’s not in order, I have implemented a new method

Sure
… but i like order?

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State the rate equation?

Rate = k[A] [B]²

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What equation do u get when involving heat with the rate equation?

Arrhenius equation

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State Arrhenius equation

K = Ae^-Ea/RT

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Define K
(Arrhenius equation)

Rate constant
(s^-1)

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Define A
(Arrhenius equation)

Frequency factor

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Define e
(Arrhenius equation)

e from the calculator lol

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Define -Ea
(Arrhenius equation)

Activation energy,
although it’s negative
(Jmol^-1

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Define R
(Arrhenius equation)

Molar gas constant
(JK^-1mol^-1)

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Define T
(Arrhenius equation)

Temperature
(Kelvin aka K)

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The “right” Arrhenius equation

In k = In A - E_a/RT

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Which has a greater effect on K when changed?
(Arrhenius equation)
(2…)

Activation energy
Alternately, so does temperature

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What’s the other way to use the Arrhenius equation?
(2….)

Using the “right” way (log on both sides)
Expressing it as y = mx + c

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How do u plot a graph based on Arrhenius equation?
(2 things)

In k against 1/T
used to determine In A and -Ea/R

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Arrhenius equation expressed in y=mx+c?
(4 steps)
(Refer to graph…)
(Actually, refer to physics type shi)

In A =
y - c = mx
c = y - mx
In A = In k - -E_a/R x 1/T

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To be continued

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What are the 5 ways of measuring the rate of reaction?

Collect gas overtime, measure volume overtime
Measure loss of mass overtime (mass balance)
Measure pH change overtime
Measure the formation of ppt
Measure color change overtime (colourimetry)

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What is “sampling and quenching”?
(2-way + 2-way + “lastly”)

Small sample of reaction mixture removed
… at regular time intervals
(Q) Put into iced water to cool
(Q) … and diluted, stops the reaction
Sample then analysed

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Rate of a chemical reaction formula?

Rate = change in conc. of (reactants/products)/time for the change to take place

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How would u gain the rate of the reaction in a graph typically?
(1 thing + 2-way)

Differentiate
Drawing a tangent
… at point of interest

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How to gain units for the rate of reaction?
(3 simple dimple)

Conc = moldm^-3
Time = min or sec
Fractional ∴ moldm^-3min^-1 or moldm^-3s^-1

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How to explain whether it’s greater at “…” mins?
(3-way structure)

Study These Flashcards

Lots of reactant particles
Increased frequent collisions
in contrast to “…”

What is the order of reactions?
(1 + 2-way)

Study These Flashcards

Always respect to each reactant involved
Considers how the conc. of reaction….
affects the rate

What are the 3 orders of reactions?

- Zero order - First order - Second order

Zero order shape?

Straight line

Zero order in terms of order of reaction? (2-way + 2-way)

- Reactant is used up - Conc. decreases - But has no effect on rate - Hence, just a straight line

So, gradient of zero order? Hence the rate? (2-way + 1 thing)

- Gradient = constant - so constant rate - Rate don't change if conc. changes

What about zero order's half life? (2-way)

- Significantly decreases - as the reaction proceeds

First order shape?

Curve

First order in terms of order of reaction?

Easily identifiable due to constant half life

Define the term "half life"? (2-way)

- Time taken for the concentration - to reduce by half

So... first order's half life? (2 things)

- Independent of concentration - Remains constant throughout reaction

Second order shape?

Also curve, but steeper...?

Second order in terms of order of reaction? (3 things + a surprise)

- Identified from the shape as well - Conc. decreases more rapidly - Half life increases with time - U don't needa know that apparently

Second order's half life :v? (2-way)

- Significantly increases - as the reaction proceeds

What is the general rate equation?

Rate = k[A]^m[B]ⁿ

Define rate? (general rate equation)

moldm^-3s^-1 (Concentration with the seconds)

Define [A] or [B]? (general rate equation)

moldm^-3 (Their concentration)

Define k? (general rate equation)

The rate constant (re-arrange for it)

Define ^m or ⁿ? (general rate equation)

Powers aka n° infront of compound (Their order of reaction)

How do u find out a reactions order of reaction? (4 steps)

- From their rate equation - Gain their powers - Add their powers = rate equation - Power of 1 = doesn't usually have 1 ofc

How do u find if its zero order with respect to the reactant? (2-way)

- Rate doesn't change - if conc. changes

How do u find if its first order with respect to the reactant? (3 steppers)

- If conc. increases by 2x - Rate increases by 2x - Likewise if 3x too

How do u find if its second order with respect to the reactant? (6 but trust me)

- If conc. increases by 2x - Rate increases by 2² = 4x - If conc. increases by 3x - Rate increases by 3² = 9x - Likewise to first order but there's always - .... a power of 2

How do u actually gain its rate equation? (We did it) (Gain examples)

Refer to its order of reaction

What do u get from finding k (Rate constant) in the rate equation? (2 things)

- The actual value - Its units

How do u get the value of k (Rate constant) in rate equation? (4 steps) (Whiteboard pls)

- Gain rate - Gain conc. of compounds - Re-arrange formula (remember powers) - Voila

How do u get the units of k (rate constant) from rate equation? (4 steps) (Whiteboard pls pls pls)

- Refer to data and units given - Sub them in, in terms of formula - Re-arrange - Voila

Define the term "reaction mechanism" (3-way)

- Series of steps - that together make up - the overall reaction

Define the term "rate-determining step" (3-way)

- The slowest step - in the reaction mechanism - of a multi-step reaction

How to predict the reaction mechanism, from just their rate equation? (...)

What i'm seeing - Gain rate equation - Find the rds (the molecules in the rate equation) - We don't know how many steps there are - But at least we know each step only has 2 molecules involved max - There's only 1 rds - The end of the step is just the overall equation -... aka the equation we used to find out the general rate equation (kinda)

What is an "intermediate" in the reaction mechanism?

- Species formed in the multi-step reaction - ... used up in a subsequent step - Not seen as reactant/product of overall equation

Could it be shorter than i think it is?

I think i'll go wid that, also prob spam ppq way more imp - Order of reactions ;-; - General rate equation ;-; - Rate determining step ;-;-;-;? - Arrhenius equation (so refer to physics) ;-;?

Ok so, yes. Not a good thing to be too clarifying u know? I hope u learn ur lesson. BUT, don't give up ofc. The ppq will carry right?

.... <_< .... We got graph paper fellas. Apparently the questions is the most to be revised on. Content wise.... light work?

Unit 3.5 Chemical kinetics Flashcards

(55 cards)