To determine how the rate of decomposition of hydrogen peroxide will change with a change in concentration of hydrogen peroxide. Hypothesis: If the concentration is increased then the rate of decomposition should increase. This is because an increase in the concentration will cause more frequent collisions. An increase in collision frequency will result in more frequent formation of products. As when the concentration of hydrogen peroxide increases there will be more hydrogen peroxide molecules in the same amount of volume causing a higher frequency of collision leading to a faster rate of reaction.
Variables: Independent: Concentration of hydrogen peroxide Dependant: The time taken to form a certain amount of products. Controlled: i?? Amount of catalyst if this is changed the rate of the reaction will change as well. i?? Amount of hydrogen peroxide as it is the concentration that is changing not the amount of hydrogen peroxide. i?? Temperature as a change in the temperature will change the rate of the reaction. i?? Environmental surroundings kept constant otherwise external changes may alter the results. i?? Room pressure kept constant, as pressure will change the rate of the reaction.
Equipment kept the same varying the equipment means the different scales of readings may have been used and if kept constant all of the results will have been performed under the same conditions. i?? Light intensity kept the same as light intensity changes the decomposition of hydrogen peroxide, as it is light sensitive. Materials: 150mL of hydrogen peroxide 250mL conical flask Stopper Gas carrying tube Manganese oxide (catalyst) Watch glass Electronic balance 50mL measuring cylinder 100mL measuring cylinder Bucket Thermometer.
Spatula Water Retort stand Clamp Boss head Stopwatch Method: 1. Put on all precautionary safety gear. 2. Half fill the bucket with water. 3. Fill the 50mL measuring cylinder with water, cover the end and invert into the water. Make sure that the end of the inverted measuring cylinder is in the water in the bucket so that it cannot come out. Hold the measuring cylinder in place using a retort stand, boss head and clamp. 4. Put the gas carrying tube through the hole in the stopper so that around two centimetres is showing out of the bottom.
With the other end of the tube cover the end, so that no water gets in the tube, and place in the bucket of water going up through the measuring cylinder so that the end of the tube is facing the bottom of the inverted measuring cylinder, release the cover of the tube. 5. Whilst wearing gloves measure out 2mL of hydrogen peroxide into the 10mL measuring cylinder and add 8mL of distilled water and mix. 6. Empty contents of the measuring cylinder into the 250mL conical flask and measure the temperature. 7. Measure out 0. 1 grams of catalyst (manganese oxide) on the watch glass with the electronic balance.
8. Add the catalyst to the conical flask, put the stopper in the top tightly and have another person start timing when the catalyst is added. All of this should be done in as short a time as possible to prevent inaccuracies in the readings. 9. Stop the timing when 40 mL of gas has been collected. Record the time that this takes. 10. Repeat Steps 2-8 using 2mL more of hydrogen peroxide and 2mL less of distilled water each time until the mixture is completely hydrogen peroxide.