Inorganic Chemistry: Rates Of Reaction

Front 1

Define rate of reaction?

Back 1

how fast a chemical change is takign place in terms of how fast reactants are removed or how fast products are formed in a given time

Front 2

Rate of reaction equation?

Back 2

Rate= Change in concentration of reactants or products/ Time

Front 3

Units of rate of reaction?

Back 3

moldm-3 s-1

Front 4

What must be stated with any result when measuring rate of reaction and remain constant?

Back 4

Temperature-it's value must be stated and recorded

Front 5

Give 6 examples of how to meausre the rate of reaction

Back 5

1) Volume of gas produced (gas syringe or water displacement)

2) Mass decrease when gas is evolved (balance)

3) colour intensity change (colorimetry)

4) pH when acids or alka;os are involved: pH probe and meter

5) Stop reaction at intervals and titrate each time (quenching)

6) Conductivity-ions produced/used

Front 6

What is the shape of a concentration time graph for a reaction of order?

Back 6

a negative gradient (straight line) ( due to reaction rate being constant)

Front 7

What is the shape of the concentration-time graph for a overall reaction of 1st order?

Back 7

Negative gradient decreases gradually over time (due to reaction depending on reactant concentraion)

Front 8

What shape is the concentration-time graph for a second order reaction comapred to a first order reaction?

Back 8

Second order had a much more steeper curve than first order

Front 9

Define half life

Back 9

The half life of a reactant is the time it takes foor it's concentration to reduce by half

Front 10

What is the rule for the half life of first order reactants?

Back 10

'If a reaction is 1st order with respect to a reactant, then the half-life is constant and independent of the concentration

Front 11

What happens to half life of 0 order reactant?

Back 11

decreases over time

Front 12

What happens to half life of 2nd order reactant?

Back 12

Increases over time

Front 13

What is the shape of a reaction rate-concentration graph for a 0 order reactant?

Back 13

Straight line, no gradient

Front 14

What is the shape of a reaction rate-concentration graph for a 1st order reactant?

Back 14

A straight line through the origin ( reaction rate is directly proportional to concentration of reactant)

Front 15

What is the shape of a reaction rate-concentraion graph for a 2nd order reactant?

Back 15

Expotentially increases (reaction rate is directly proprotional to concentration of the reactant SQUARED)

Front 16

Describe intitial rates metod

Back 16

Several different experiments are carried out, where in each separate experiment the initial reaction rate is estimated for one different initial reactant concentration with all other variables unchanged

Front 17

What is approximately true about the the initial rate of reaction?

Back 17

The rate of reaction is constant

Front 18

Equation of initial reaction rate is:

Back 18

[reactant] (initial) - [reactant] (t) / time,t

Front 19

What was the clock reaction?

Back 19

Initial rate is appromiately directly proportional to 1/t

If total volume was kept constant, the solution used with be proportional to it's concentraion

Front 20

what is the rate determining step in a reaction mechanism?

Back 20

The slowest step and controls how fast the reaction proceeds

Front 21

How can you determine the order of reactants from the rate determining step?

Back 21

'The number of each chemical species reacting in the rate determining step equals its orderin the rate equation'

Front 22

What happens to the Rate constant (k) when temperature increases?

Back 22

Rate constant is only constant at constant temperature; k increases dramatically (exponentially) when temperature increases and therefore so does rate

Front 23

What does the Arrheuis equation show?

Back 23

Shows the exponential relationship between the rate constant K and absolute temperature T (in kelvin)

Front 24

In the data book, what form is the Arrheuius equation in?

Back 24

y = mx + c

Front 25

What is the equation to work out Activation energy? (Ea)

Back 25

Ea = - (m (gradient) x R (Gas constant)

Front 26

What is the equation to work out A (frequency of successful collisions)?

Back 26

e c (to the power of c-which is the intercept)