To Investigate One Factor That Will Affect the Rate of Decomposition of Hydrogen Peroxide.

INVESTIGATION OF THE

Aim: to investigate one factor that will affect the rate of decomposition of hydrogen peroxide.

The equation for this reaction is;~

Hydrogen peroxide -----------------------> oxygen + water

2H O -----------------------> O + 2H O

Rate of reaction means the time in which the reaction takes place. Key factors that may affect this reaction are temperature, pressure, surface area, light, concentration, type of catalyst or amount of catalyst.

The factor that I will investigate, will be the amount of catalyst.

Prediction: I predict that when the catalyst (Maganese IV Oxide) is added to the hydrogen peroxide, small bubbles of oxygen will appear in seconds. They will then collect in the gas syringe, therefore making it expand.

If I were to double the amount of catalyst then the rate of reaction would also double as a result.

Hypothesis: The theory behind my prediction is that the catalyst decomposes the hydrogen peroxide at a faster rate than if the catalyst was not added at all. Because when the hydrogen peroxide is alone the particles are not colliding very often and they collide quite gently. However when the catalyst is added it increases the amount of particles, so the particles are closer togther and they have a greater chance of colliding with one another and making more of an impact. So because of the increase in collisions the reaction rate is faster. Also due to the fact that the reaction takes place at the surface of the catalyst, this increases the suface area which in turn will make the number of collisions greater.

BEFORE CATALYST WHEN CATALYST IS ADDED

Apparatus: I will use......

o A glass syringe, due to the flow of oxyen being more smooth ...

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BEFORE CATALYST WHEN CATALYST IS ADDED

Apparatus: I will use......

o A glass syringe, due to the flow of oxyen being more smooth through a syringe and the reading being more accurate.

o Conical flask with rubber tube that will connect to glass syringe and remain completely airtight.

o Measuring cylinder (to measure the hydrogen peroxide), to get a more accurate reading of hydrogen peroxide.

o Balance (to measure the amount of catalyst), because it is more accurate for measuring small amounts of powder.

o Goggles, as a safety precaution so that no chemicals will get into my eyes.

o Clamp, to hold the syringe level and keep the measurements accurate.

o Catalyst: Maganese IV Oxide.

o Hydrogen peroxide

o a pipette for the hydrogen peroxide.

o a spatula for the Maganese IV Oxide.

o stop clock for measing time accurately.

Method: First I will set up the clamp with the glass syringe and make sure that it is level. Then I will make sure that the rubber pipe connected to the syringe, from the bung of the beaker is tight. I will then make sure that the syringe reads zero.

Next I will measure 5cm of hydrogen peroxide, using the pipette I will squeeze it into the measuring cylinder. Making sure that the cylinder is flat on the lab bench to ensure that the readings are precise. I will then measure x amount of catalyst on the balance.

I will then take the bung from the beaker, pour in the hydrogen peroxide and add the catalyst. Immediately I will replace the bung and start the stop clock.

I will then record the reading of oxygen in the syringe every 15 seconds, until the reaction has stopped. In between these readings I will twist the syringe gently to prevent sticking.

I will use these different amounts of catalyst; 0.1g

0.2g

0.3g

0.4g

0.5g

I will also rinse the beaker out after each experiment, and make sure that it is completely dry, before the next experiment. I will repeat each experiment twice.

Risk assessment: It is important that I wear goggles throughout each experiment as a safety precaution, so that I do get any chemicals into my eyes. It is also important that I stand up whilst doing each experiment as this lowers the danger of getting hurt if part of the apparatus were to fall towards me.

Whist in the lab it is important to keep all bags under the lab benches at all times and make sure that the lab benches are clear of objects not being used whist doing an experiment.

Accuracy/precision: Here are some main points that I will use to make my experiments more accurate ; Make sure that measuring cylinders are vertically level.

Don’t lean on the lab bench.

Put the bung in quickly.

When measuring the catalyst use the tare button.

Rinse out beaker between experiments.

Repeat each experiment.

Twist syringe gently whist doing experiments.

Results:

Time ---- amount of catalyst ----------- --------second experiment --------

Amount of Oxygen

EVALUATION:

Think that my results are fairly accurate as I took into account a lot of factors to make sure that my results would be precise (such as keeping the cylinders vertical, etc.). However I feel that I could have made my results more accurate if both of my experiments had been preformed on the same day. This would have also probably prevented any anomalous results that I gained. As they were not I have considered that there may have been a change in temperature which could have distorted my results.

To improve my method could measure the room temperature a make sure that it remained the same throughout the experiment. Otherwise I would consider my method as being accurate and quite a sound method to use again if necessary. This is the only change I would make to my method.

I feel that my results are a good source to prove my hypothesis as the reaction of the hydrogen peroxide does speed up due to the catalyst. I feel that they could be made more reliable if I have controlled the environment further by keeping the temperature the same.

Another experiment that I could do to back up my conclusions would be to measure the volume of gas by collection over water. I would do this with a measuring cylinder (to collect the oxygen), a trough filled with water, an airtight beaker and a delivery tube to connect the two.

See Diagram below............