Rate Law Lab
Introduction The purpose of this experiment was to determine the rate law graphically from the rate of disappearance and the x y values also the specific rate constant (k). Activation energy was also determined, and the effect of catalyst was evaluated in the reaction between peroxodisulphate ion S2O82-, and iodide ion, I-.
S2O82-(aq) + 3 I-(aq) --> 2 SO42-(aq) + I3(aq) The general expression for the rate law, given this overall reaction, is: rate of disappearance of S2O82- = k[S2O82-]m[I-]n Chemical Kinetics is the chemistry of how fast or slow something is. These rates of reaction or the speed depends on many factors. Experiments show that the rate of homogenous reactions depend upon: The nature of the reactants, the concentration …show more content…
At the top of this energetic barrier, there is a transition state complex that forms instantaneously before the products are formed. The difference in energy between the initial reactants and the activated complex C is the activation energy, Ez of the reaction (Department of Chemistry and Biology, 2012). Arhenius’s equation can be used to determine the activation energy.
The rate of a reaction is determined by observing the rate of disappearance of the reactants.
Rate of disappearance of A = change in concentration of A/time reacquired for change = -∆A/∆T
Rate of appearance of C = change in concentration of C/time reacquired for change = ∆C/∆T
Procedure
Effect of Concentration 4 reaction solutions were prepared in 250 mL flask. In flask A 25.0 mL KI solution was added in a flask using a graduated cylinder. 2 separate 1 mL pipettes were used for measuring 1.0 mL Na2S2O3 and starch solutions (Department of Chemistry and Biology, 2012). These 2 solution were also added to flask A. 48.0 mL KNO3 solution was added into Flask A. 25.0 mL of (NH4)S2O8 (ammonium peroxodisulphate) was measured in a 100 mL dry beaker, named Beaker B …show more content…
S2O82-(aq) + 3 I-(aq) --> 2 SO42-(aq) + I3(aq) The data was calculated from the solutions, and the rates shown below in Table 1. The rate law for each experiment was determined by the rate law:
Rate = k[S2O82-][I-]
Table 1: Concentration Dependence of Reaction
Experiment |[S2O82] |[I-] |Initial rate | |1 |0.050M |0.050M |1.068 x 10-5 mole/ L.s | |2 |0.10M |0.050M |2.623 x 10-5 mole/ L.s | |3 |0.05M |0.10M |2.326 x 10-5 mole/ L.s | |4 |0.10M |0.025M |9.661 x 10-6 mole/ L.s | |1T2 |0.050M |0.050M |3.158 x 10-5 mole/ L.s | | The rate of each reaction was determined through this table. The slope for each experiment was determined. An example for such experiment A follows:
Slope = ∆S2O82-/∆T
= [(10.0-2.0) x 10-4 mole]/(22.5-4.8)sec
= [8.0 x 10-4 mole]/17.7 sec
= 4.5 x 10-5 mole/sec
The rate would be : [4.5 x 10-5 mole/sec]/0.075 litre = 6.0 x 10-4 mole/litre
S2O82-(aq) + 3 I-(aq) --> 2 SO42-(aq) + I3(aq) The general expression for the rate law, given this overall reaction, is: rate of disappearance of S2O82- = k[S2O82-]m[I-]n Chemical Kinetics is the chemistry of how fast or slow something is. These rates of reaction or the speed depends on many factors. Experiments show that the rate of homogenous reactions depend upon: The nature of the reactants, the concentration …show more content…
At the top of this energetic barrier, there is a transition state complex that forms instantaneously before the products are formed. The difference in energy between the initial reactants and the activated complex C is the activation energy, Ez of the reaction (Department of Chemistry and Biology, 2012). Arhenius’s equation can be used to determine the activation energy.
The rate of a reaction is determined by observing the rate of disappearance of the reactants.
Rate of disappearance of A = change in concentration of A/time reacquired for change = -∆A/∆T
Rate of appearance of C = change in concentration of C/time reacquired for change = ∆C/∆T
Procedure
Effect of Concentration 4 reaction solutions were prepared in 250 mL flask. In flask A 25.0 mL KI solution was added in a flask using a graduated cylinder. 2 separate 1 mL pipettes were used for measuring 1.0 mL Na2S2O3 and starch solutions (Department of Chemistry and Biology, 2012). These 2 solution were also added to flask A. 48.0 mL KNO3 solution was added into Flask A. 25.0 mL of (NH4)S2O8 (ammonium peroxodisulphate) was measured in a 100 mL dry beaker, named Beaker B …show more content…
S2O82-(aq) + 3 I-(aq) --> 2 SO42-(aq) + I3(aq) The data was calculated from the solutions, and the rates shown below in Table 1. The rate law for each experiment was determined by the rate law:
Rate = k[S2O82-][I-]
Table 1: Concentration Dependence of Reaction
Experiment |[S2O82] |[I-] |Initial rate | |1 |0.050M |0.050M |1.068 x 10-5 mole/ L.s | |2 |0.10M |0.050M |2.623 x 10-5 mole/ L.s | |3 |0.05M |0.10M |2.326 x 10-5 mole/ L.s | |4 |0.10M |0.025M |9.661 x 10-6 mole/ L.s | |1T2 |0.050M |0.050M |3.158 x 10-5 mole/ L.s | | The rate of each reaction was determined through this table. The slope for each experiment was determined. An example for such experiment A follows:
Slope = ∆S2O82-/∆T
= [(10.0-2.0) x 10-4 mole]/(22.5-4.8)sec
= [8.0 x 10-4 mole]/17.7 sec
= 4.5 x 10-5 mole/sec
The rate would be : [4.5 x 10-5 mole/sec]/0.075 litre = 6.0 x 10-4 mole/litre