rates equations

Question 1

the rate of a chemical reaction is related to

Answer 1

the concentration of reactants

Question 2

rate eqaution form

Answer 2

rate = k[A]^m [B]^n
where m and n are orders of reaction with respect to A and B
k is the rate constant

Question 3

order of reaction is restricted to

Answer 3

0,1 and 2

Question 4

the rate constant k varies with

Answer 4

tempertaure

Question 5

arrhenius equation

Answer 5

Ae ^(-Ea/RT)
k = rate constant (same units as A)
A = arrhenius constant(same units as k)
e= mathmatical constant
Ea= activation energy (J)
R= molar gas constant (J mol-1 K-1)
T= temperature (K)

Question 6

define rate of reaction

Answer 6

the change in concentration per unit time
mol-1 dm-3 s-1

Question 7

define activation energy

Answer 7

the minimum amount of energy required to start of reaction
endothermic

Question 8

what do the differnet orders of reaction mean

Answer 8

zero- changing concentration has no effect on the rate
first- rate directly proportional to the change in concentration of reaction
second - rate proportional to the square of change in concentration

Question 9

rearrangement of arrhenius eqaution

Answer 9

ln k = ln A -(Ea/RT)

Question 10

deine the rate constant

Answer 10

the rate of reaction when all concentrations are 1 mol dm-3
specific for every reaction

Question 11

how to determine order of reaction with respect to each reactant

Answer 11

only determined by experiment

Question 12

what are the 2 types of experiment that can be done to determine the order with respect to different reactants

Answer 12

continuous monitoring method (following the course of a single reaction)
initial rates method (doing multiple experiments)

Question 13

how to measure the progress of reaction in continuous monitoring method and its problems+ solutions

Answer 13

by taking samples at regular intervals, much quench the reaction when sampling by adding a large volume of cold distilled water to both cool and dilute the reaction decreasing the rate
OR
by using a visible indicator/ physical properties such as a gas syringe to measure gas volume, this mearsures the amount of product produced and the order of reaction is about reactants so volumes recorded would need converting to reactant concentration
if colour changing reaction use colorimetry

Question 14

how to use reuslts of continous monitoring to work out orders

Answer 14

CTT graphs (concnetration time and tangent)
plot concenration on y axis and time on x axis, draw tangent at any value of t and the gradient of the tangent will give the rate of reaction at that specific moment in time. do this is different concentration and compare facto of change in conc to factor of change of rate worked out by gradients

Question 15

graph of zero order reaction

Answer 15

straight line as change in conc does not affect rate

Question 16

finding the order of reaction from the intial rate experiment

Answer 16

a sereies of reaction is carried out in which the concentration of one reactant is changes each time, mearsure the time taken to react rate is 1/T then a graph of rate vs conc can be plotted and the shape of the line indicates the order
zero order- horizontal line
first order- diagonal line
second order- curved line

Question 17

use the orders with respect to reactants to provide infomation about the rate determining/ limiting step of a reaction

Answer 17

the species in the rate determining step must match the species in the rate equation
no matter how fast the other steps may be the overall reaction must be deterinined by the one slowest step