Kinetics Calculations Lab Manatee Community College Pre-Lab
1. Express the rates of the products and the reactants in terms of changes in concentration with time for the following reaction
H2(g) + 2 ICl(g) I2(g) + 2 HCl(g)
2. Name four factors that may affect a reaction rate 1.
2.
3.
4.
3. For the following reaction 3 experiments have been run and the data collected is in the following table
A + 2 B C
Experiment [A], M [B], M Rate, mol/L s 1 1.0 x 10-2 1.0 x 10-2 1.5 x 10-6 2 1.0 x 10-2 2.0 x 10-2 3.0 x 10-6 3 2.0 x 10-2 1.0 x 10-2 6.0 x 10-6
a) Find the order with respect to A
b) Find the order with respect to B
Kinetics Calculations 1 c) What is the overall order?
d) Write the rate expression
e) Calculate the rate constant, k
f) If [A] = 1.5 x 10-3 M and [B] = 3.25 x 10-3 what is the rate of the reaction?
Kinetics Calculations 2 Kinetics Calculations Lab
1) For the following reaction 4 experiments have been run and the data collected is in the following table 2 A + B + C D + E
Experiment [A], M [B], M [C], M Rate, mol/L s 1 0.20 0.20 0.20 2.4 x 10-6 2 0.40 0.30 0.20 9.6 x 10-6 3 0.20 0.30 0.20 2.4 x 10-6 4 0.20 0.40 0.60 7.2 x 10-6
a) Find the order with respect to B
b) Find the order with respect to C
c) Find the order with respect to A
d) What is the overall order?
e) Write the rate expression
f) Calculate the rate constant, k
Kinetics Calculations 3 2) For the following reaction 2 experiments have been run and the data collected is in the following table @ 25C A products
Experiment [A], M Rate, mol/L s 1 1.2 x 10-2 1.33 x 10-5 2 2.6 x 10-3 6.26 x 10-7
a) What is the order with respect to A
b) What is the overall order
c) Write the rate expression
d) Calculate the rate constant, k
e) How long will it take for a 50% solution to become a 24% solution @25C?
f) It has been determined that at 63 C the rate constant is .2450L/mols, Calculate the activation energy for the decomposition of A Lnk2/k1=Ea/R [1/T1 -1/T2]
Kinetics Calculations 4 g) What is the half life of a 72% solution of A @ 25C
3) The three step mechanism for the following reaction can be seen below
2 A + 2 B C + 2 D
Step 1: 2B + G E Slow Step 2: E + A D + F Fast Step 3: F + A C + D + G Fast
a) Are there any intermediates in the reaction mechanism for this reaction? If so what are they?
b) Is there a catalyst in this reaction mechanism? If so what is it?
c) Does this reaction mechanism have a rate determining step? If so which step is it?
Kinetics Calculations 5 4) A first order reaction A B has a half life of 230 sec. at 25°C
a. What is the rate constant?
b. If you start with 45.8 g of A how long will it take to consume 32.0 g of A?
c. How long does the reaction have to be carried out so that the reactant is 99% consumed?
d. An unknown mass of A is allowed to react for 30 min. After that time 5.60 mg of A remains. What was the mass of the original sample?
e. If you start with 35 kg of A how much will remain after 15 min?
f. What percent of the starting amount is consumed after the reaction is allowed to occur for 10 half lives?
Kinetics Calculations 6 g. If the activation energy for the reaction is 55 kJ/mol what is the rate constant at 40C?
Post-Lab
The following data was collected for the concentration of a reactant as a function of time.
TIME CONC. (sec) (M) 0 1 100 0.96 200 0.92 500 0.82 750 0.75 1000 0.69 2000 0.53 3000 0.43 5000 0.31 Determine what the order of the reaction is and what is the rate constant. (Hint: use MS Excel!)
Kinetics Calculations 7