Chemical Reaction Lab

Introduction
The reaction rate of a chemical reaction is determined as the change in the concentration of a reactant or product over the change in time. [1] The rate of a reaction is determined by experiment. Many factors influence the rate of a reaction: the nature of the reaction, concentration, pressure, temperature, and surface area, presence of catalyst and intensity of light. [2]
For a chemical reaction, the rate law or rate equation is a mathematical expressed equation that links the reaction rate with the concentration or pressures of each reactant. There are two types of rate laws: differential rate law and integrated rate law. [3] The differential rate law, often simply called the rate law, expresses how the rate depends on the
The exact time was noted for each the sample mixes with the quenching NaHCO3. In order to ensure complete quenching the mixtures in the flasks were swirled again, without stopping the clock.
Finally, using the burette filled with the solution of Na2S2O3 the contents of each of the flasks T3 to T7 were titrated and a starch was used as an indicator.
All the obtained results were recorded in a table. A graph of the titres of sodium thiosulphate versus time from the start of the reaction was plotted from which the order of reaction with respect to iodine was deduced.
Method 2. Determining the rate of a reaction with respect to iodine
Using the burettes the four mixtures of hydrochloric acid (HCl), propanone (CH3COCH3) solution and water were made up in the conical flasks according to the table 2.
The volumes of iodine needed for each run were measured out from the burette into four test tubes. The tubes were marked as w, x, y and z.
By adding the contents of the test tube w to flask W the first run was started. Simultaneously, the timer was started and the time taken for the iodine to disappear was measured in seconds.
The procedure was repeated for the other three runs (X, Y and Z)
4) What does this tell you about the order of reaction with respect to one (which?) of the reactants?
The order of reaction with respect to iodine is zero. This can be explained by the drawn straight-line in the graph. The gradient is constant which means the rate of reaction is independent of the concentration.

5) In Method 2, why was the volume of water added different for each of the four reaction mixtures (W to Z)?
The reason why the volume of water was added different for each of the four mixtures is to equalize the volume of overall reaction as different amounts of hydrochloric acid (HCl) and propanone (CH3COCH3) were mixed together to make up a solution.

6) If you compare the mixtures for runs W and X you will see that the concentrations of propanone and iodine are the same but the concentration of acid in run X is half that used in run W. What is the effect on the rate of halving the concentration of HCl?
The hydrochloric acid is found to be a catalyst in this reaction. Therefore, as it is reduced then the rate of reaction slows down and decreases approximately to half.

7) What is the order of the reaction with respect to hydrogen