Simulatioon-effect Of Concentration On The Reaction Rate

1

UNIVERSITI PENDIDIKAN SULTAN IDRIS TKU 3023 INFORMATION TECHNOLOGY AND COMMUNICATION IN CHEMISTRY ASSIGNMENT : SIMULATION TITLE : EFFECT OF CONCENTRATION ON THE RATE OF REACTION NAME NOOR ZATILAKHMA BT DANI NUR SAHIDA BT MAT HUSIN

MATRIC NUMBER D20081032322 D20081032326

GROUP : B ( THURSDAY- 1P.M-4P.M) LECTURER’S NAME : MISS ASMAYATI BINTI YAHAYA DATE OF SUBMITTED : 8 th OCTOBER 2009

EFFECT OF CONCENTRATION ON THE RATE OF REACTION

2 The reaction rate or rate of reaction for a reactant or product in a particular reaction is intuitively defined as how fast a reaction takes place. For example, the oxidation of iron under the atmosphere is a slow reaction which can take many years, but the combustion of butane in a fire is a reaction that takes place in fractions of a second. Chemical kinetics is also the part of physical chemistry that studies reaction rates. Rate of reaction can be calculated by using the formula as below:

Rate of reaction =

Quantity change of reactants/products Total time for the reaction

The rate of a reaction is the speed at which a reaction happens. If a reaction has a low rate, that means the molecules combine at a slower speed than a reaction with a high rate. Means that the reaction occurs at a slower speed and the time taken for reaction to complete is long. But if the reaction has a high rate, that means the molecules combine at a higher speed and the time taken for the reaction to complete is shorter than the reaction with the low rate of reaction. Concentration of reactant is one of the factors that can affect the rate of reaction. Concentration is the measure of how much of a given substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of solute in the solvent. Reaction rate increases with concentration because the increasing numbers of reactant molecule that will be react with another reactant. As the number of reactant molecule increase, the frequency of collision between the reactant molecule also will be increase. As a result, the frequency of effective collision also will be increase. Effective collision is the collision that can cause the reaction to occur and the new product will be produce. So, if the reactant with high concentration is used, the rate of reaction will high. ENGAGE

3

The power of salt

SALT FISH

1. What the effect of using high concentration of salt solution compare using water solution on the time taken for the fish to dry ? 2. How the concentration of solution can affect the rate of reaction ?

EMPOWER

4 1. Students plan an experiment to observe the effect of concentration of reactant on the rate of reaction. 2. The students are given the following apparatus:

 Measuring cylinder  Stopwatch  Beaker  Sodium thiosulphate ( 0.5M, 1.0M, 2.0M )  Sulphuric acid (1.0M )

3. Students have to construct a hypothesis before doing the experiment. 4. Students should know the effect of concentration on the rate of reaction. 5. Students have to determine the variables involves. 6. The procedures of conducting the experiment are discussed. 7. The time taken for the X mark on the bottom of beaker to disappear is recorded. 8. Log on to the website and observe the animation to answer the question :

http://freezeray.com/flashFiles/RatesOfReactionConc.swf

* Note: click on any bottles to view the reaction in terms of particle collisions. The program can be reset by clicking on the stopper

5

Result :

The apparatus for this experiment

6

The reaction between H2SO4 and 0.5M Na2S2O3

The reaction between H2SO4 and 1.0M Na2S2O3

7

The reaction between H2SO4 and 2.0M Na2S2O3 Question: 1. Predict which concentration will cause a) Highest the rate of reaction. b) Lowest the rate of reaction. 2. Give the reason for your answer in a and b. 3. How the concentration can affect the rate of reaction?

Answer : 1.a) 2.0 M b) 0.5 M 2. a) Time taken for reactant to react completely is the shortest b) Time taken for reactant to react completely is the longest 3. By using the high concentration solution of reactant, the rate of reaction will increase due to time taken for the reaction to complete. The number of reactant

8 molecule that exists in the process also high and increase the number of collision that occurs per time. It will result the increasing number of effective collision that occurs per time. So, the time taken for reaction to complete will decrease cause the rate of reaction to increase. But, by using the low concentration of reactant, the result that will be obtained is apposite with the result of using high concentration of reactant.

ENHANCE

In the process of latex vulcanization, we need to use formic acid in suitable concentration. Which is the most suitable concentration of latex solution for molecules of formic acids to react with molecules of latex more faster? What happen to the

9 solution of latex when we add the formic acid into latex solution with different concentration?

Answer: The modest concentration of formic acid is with pH=4 because this pH is the most suitable acid used for vulcanization of latex. For example, two solution of latex is prepared which both of the latex has different concentration of latex. In solution A the latex concentration is 20% while in solution B the latex concentration is 5%. When we add the same amount of formic acid that is 5 ml into both of the solution, we can see latex vulcanization in the solution A occur more faster compare to the solution B. This is because the high concentration of solution A caused the molecules of formic acids to react with molecules of latex more faster. So, when the concentration increase, the rate of reaction also increase. Thus, the rate of reaction in solution A is faster. However the latex vulcanization in this solution is imbalance because when the suitable concentration of acid added into latex solution, not all the acids react with latex solution. That’s why the latex vulcanization is imbalance.