Then I will pour the hydrochloric acid out of the measuring cylinder and into the flask and as soon as the chemicals are mixed I will start the stop clock straight away. I will then look down the flask to look at the cross until I cant see the cross no more and at that point where I cant see the cross any more I will stop the stop clock straight away. I will then record the time down in my book. I will then wash the flask out and make sure the stop clock has been reset and repeat this experiment again and record the time of reaction again so that I can work out an average time for this test.
I will then reset the stop clock and will wash out the flask. After them two tests I will then pour 25mls of sodium thiosulphate into the 25mls-measuring cylinder with the letter ‘T’ marked on. And then I will pour 5mls of hydrochloric acid into the 25mls-measuring cylinder, which doesn’t have a letter ‘T’ on it. And then I will pour 10mls of water from the water taps into the 10mls-measuring cylinder and pour the water out of the measuring cylinder and into the flask. And then I will pour another 10mls of water from the water taps into the 10mls-measuring cylinder and pour the water out of the measuring cylinder into the flask.
The amount of water has to be measured twice because the amount of water needed is 20mls and the measuring cylinder will only measure upto 10mls. I will then check that the stop clock has been reset and then I will pour the sodium thoisulphate out of the measuring cylinder and into the flask. Then I will pour the hydrochloric acid out of the measuring cylinder and into the flask and as soon as the chemicals are mixed I will start the stop clock straight away. I will then look down the flask to look at the cross until I cant see the cross no more and at that point where I cant see the cross any more I will stop the stop clock straight away.
I will then record the time down in my book. I will then wash the flask out and make sure the stop clock has been reset and repeat this experiment again and record the time of reaction again so that I can work out an average time for this test. I will then reset the stop clock and will wash out the flask. Preliminary Work I predicted that when the volume of hydrochloric acid is removed the reaction rate would slow down. I feel this way because I feel that when the volumes of an object or liquid is reduced its reaction will slowdown.
The reason I feel this way is from past investigations, which I have carried out such as the investigation on burning fuels. The investigation was which fuel out of paraffin, methylated spirit and olive oil could heat up water the most in five minutes. Out of the three fuels the paraffin was the best at heating up the water compared to the results of the other fuels and the volume of the paraffin was used up the most out of the other fuels. The results of the investigation were: – 0As you can see the results of the past investigation shows that the paraffin was the most effective at heating up the fuels and the volume of the paraffin was used up the most.
The reason why the paraffin gave of more heat is because the paraffin is more flammable than methylated spirit and olive oil. And also the reason for paraffin being more flammable than the other fuels is because paraffin has smaller hydrocarbons than the other fuels so it was a lot more easier for the hydrocarbons to react with oxygen because it has smaller hydrocarbons. That is also the reason why more of the volume of the fuel was used up because the chemical bonds were is to break. The smaller the bonds in the volume the more small bonds in the paraffin.
Therefore the volume of the paraffin will be more concentrated than the other fuels because it has smaller bonds. This piece of evidence explains the results for the burning fuels investigation and also supports my prediction because in the paraffin the concentration is high that is why the fuel was more effective at heating up the water and why the volume was used up more. I have also written in my prediction that the volume of hydrochloric acid can effect the results because when the hydrochloric acid is reduced and water displaces the volume lost than the hydrochloric acid and sodium thiosulphate will be even more diluted.
This will cause the concentration of the solution to drop, which will then result to the reaction rate to slow down even more. Research From doing some research from a scientific book on rates of reaction I have learnt a few things in this area. From doing some research from the book I have been educated that the faster the cross under the flask is blotted out by the milky solution the faster the reaction is taking place. Therefore the reaction rate is timed in milliseconds so that we can see how fast a reaction is taking place in the finest detail.
I have been taught that in order for the cross to be blotted out by the milky solution a certain amount of sulphur particles must be formed in the volume. From this I have also been taught even do you are measuring the reaction rate you are also measuring the time it takes to produce a certain amount of sulphur. In the book it clearly states that if you use one dilute acid solution it might take 100 seconds for the cross to be blotted out but if you use a more highly concentrated acid you it might only take about 10 seconds for the cross to be blotted out.
This evidence from the scientific book clearly defends my prediction, which I have predicted. I have learnt a few factors, which can also affect the rates of reaction from reading the book. Theses are also a few factors, which I must control in the investigation so I get accurate and reliable results. Concentration This can affect the reaction rate by changing the volume of acids or chemicals in the mixture. Pressure This can affect the reaction rate by increasing or decreasing the pressure of the solutions for quick burst of acids or chemicals.
This done by forcing a liquid down a tub which gradually goes smaller so that the pressure of the liquid increases. Temperature This can affect the reaction rate by increasing or decreasing the temperature of the liquids. If you heat up the acid it will become more reactive because the molecules in the acid is being given more energy because they are being heated up. This causes the molecules to move about a lot faster so that they bump into the molecules of the other acid a lot quicker so that they are given the activation energy to react with each other. Light
This can affect the reaction rate by shining light on the acid, which will radiate heat to the molecules in the acid so that they are given the activation energy to react with each other. A good example of light being used for reactivity is in a plant where light is needed for photosynthesis so they can reproduce. Surface Area This can affect the reaction rate by increasing or decreasing the surface area of what is going to be combined with another solution. I. e. the larger the surface area the faster the reaction rate will be, the smaller the surface area the slower the reaction rate will be.
For example if you get a hard boiled sweet and put it in you mouth your saliva will come in contact with the surface area of the sweet and will begin to dissolve the sweet. But if you crush the sweet in your mouth you will engage a larger surface area of the sweet because the surface area of one small piece added with the rest of the surface area of the other smaller pieces will add up to a larger surface. Therefore the surface area of the crushed pieces is larger than the sweet at the beginning when the sweet was as a whole.
Catalysis This can affect the reaction rate by increasing or decreasing the reaction rate depending on the catalysis introduced. A catalyst can be a liquid or solid like hydrochloric acid or sodium thiosulphate, which can affect the reaction rate by the concentration and the volume of the substance. But the difference between a catalyst and a normal reactive acid is a catalyst has one great big advantage, which is it can be used over and over again without the catalyst being used up.
An example of a catalyst is it can be used in a car battery so it can be used again without it being used up but the process of the battery system must have a catalytic converter so the energy can be converted into electricity. In the book I am told how I can find out how concentration affects the reaction rate. In the book it states use a measuring cylinder to measure out equal volumes of dilute hydrochloric acid, then measure out different volumes of sodium thiosulphate solution. Then it tells you to add water to each test series so that the total volume of each test series is equal.
Then it says to add reactant A to reactant B and then to measure the time it takes for the cross to be blotted out and repeat the test so you get a more reliable result which is important. From reading the scientific book my knowledge on reaction rates have been reinforced with more reference. I have also learned a lot more reference on reaction rates from reading the scientific book about the collision theory. I can use the kinetic theory to try and explain the factors affecting the rates of reaction. This extension on the kinetic theory is called the collision theory.
In the collision theory it gives an example of reaction between methane (natural gas) and oxygen. For the reaction to take place the methane molecules must collide with the oxygen molecules with enough energy for the gas to ignite. The force applied to the molecules is called the activation energy otherwise both types of molecules will just bounce in to each other harmlessly. The reason for the activation energy is to break the bonds in the molecules and get the reaction started. This is why methane and oxygen do not react at room temperature.
For example if you open a gas tap on the bunsen burner in the science laboratory and let the methane mix with the oxygen molecules in the air the gas will not ignite because there is no activation energy. But if you were to cause a spark near the molecules the molecules will begin to react with each other and will cause a flame of fire. The spark will cause heating to the molecules to provide the activation energy. The spark is the activation energy applied to the molecules for a reaction to occur between both methane and oxygen.