Rate Equations

Question 1

What is the order of a reaction

Answer 1

With respect to a particular reactant is power which the concentration is raised in rate equation
0 order- changing concentration has no effect on rate
1st order- changing concentration changes rate by same factor
2nd order- changing concentration changes rate by the factor squared

Question 2

Effect of temperature on rate constant

Answer 2

As temperature increases, rate constant increases

Question 3

Effect of catalyst on rate

Answer 3

Lowers activation energy
Arhenius constant remains unchanged
Significant rate on chemical reaction rate

Question 4

Graph analysis of arhenius equation

Answer 4

Ln(k) = -(Ea/RT) + ln(A)
Gradient: (-Ea/R)
Intercept: ln(A)

Question 5

Methods to determine rate of reaction

Answer 5

Measuring gas volume
via gas syringe, Plot gas volume against time, calculate initial rate with tangent at 0s
Via change in mass, plot mass against time, calculate initial rate with tangent at 0s
Measuring coloured reactant/product
Colorimetry, set up calibration curve of known samples, plot absorbence against time
Titration
Sampling then quenching at various times and then titrating to see concentration
Ph monitoring- values taken over time, plot [H+] against time

Question 6

Initial rate monitoring

Answer 6

Gas production
Coloured substances
Changing pH
Carry out several experiments at different concentrations measuring quantity against time
Plot quantity against time
Draw tangent at 0s to calculate initial rate
Repeat for variety of concentrations
Plot graph of initial rate against concentration
Horizontal straight line 0 order
Straight line through zero 1 order
Curve 2 order

Question 7

Continuous rate monitoring

Answer 7

Used when concentration of reactants can be determined directly
pH, coloured reactant, titration
Allows reaction to progress and take readings/samples at regular intervals
Samples quenched by rapid cooling
Plot graph of concentration against time
0 order is straight decreasing line
1st order is decreasing curve
2nd order is bigger decreasing curve

Question 8

Rate determining step

Answer 8

Slowest step in a reaction dictating overall rate
Species are in same quantities as reactants in rate equation