Chemical Kinetics
Abstract
This experiment was done to determine the effects of the nature of the reactants, concentration, temperature, surface area and catalyst on the rate of chemical reactions. The nature of the reactants implies a difference if the reactants are aqueous or organic, acidic or basic or if they occur in the same phase or not. Acid-base reactions, formation of salts, and exchange of ions are fast reactions while reactions in which large molecules are formed or broken apart are usually slow. Generally, the rate of reaction is directly proportional to the concentration of the reactants, as well as to the temperature. Greater surface areas and addition of catalysts also increase the rate of chemical reactions. …show more content…
Ten drops of 3 M HCl was then added and the time when the solution became cloudy was recorded. The same procedure was done, heating the solution to 60o C and cooling it to 40o C.
Effect of Surface Area A small piece of chalk was placed in a 5-mL test tube. Another piece of chalk with the same size was ground and put in a second test tube. Twenty drops of 1 M HCl was added into each test tube and the relative rates of reaction were compared.
Effect of Catalyst Ten drops of freshly prepared H2O2 and a pinch of MnO2 were mixed in a test tube. The evolution of gas was noted. The same procedure was done but this time without adding MnO2. The relative rates of gas evolutions in the two systems were then compared.
Results
Table 1. Effect of the Nature of Reactants on the Rate of Disappearance of Pink Color Reducing Agent | Rate of Disappearanceof Pink Color | Na2C2O4 | slower | H2O2 | faster |
Table 2. Effect of the Concentration of HCl on the Dissolution of Mg Ribbon Concentration of HCl | Relative Rate of Reaction | 6 M | fastest | 3 M | fast | 1 M | slow |
Table 3. Effect of Temperature on 3 M HCl Temperature (oC) | Relative Rate of Reaction …show more content…
The HCl solution which was heated to 60o C had the fastest rate of reaction.
Increasing the temperature in a solution causes the particles to move faster, and thus, these particles collide with each other more frequently. The greater the number of collisions per second, the greater the reaction rate. However, increasing the temperature will not always increase the rate of reaction. Most enzymatic reactions occur faster in higher temperatures. But, a very high temperature can cause denaturation of these enzymes, thus causing a halt to such