The experiment went on for about 4 minuets so we could get a good range of results for each type of crystals. it off then. I could not control the room temperature but I assumed that the room temperature would stay around the same for the duration of the experiment as it could affect the rate of reaction.
Rates of Reaction:
Rate is the speed at which a reaction occurs. The slowest reactions are those
such as the rusting of iron. Reactions with a moderate speed are those such as
magnesium reacting with an acid to produce a gentle stream of bubbles, and rapid
reactions are those such as potassium with acid, in which an explosion occurs
and the reaction is over in a fraction of a second.
Hypothesis:
A reaction occurs when particles collide. This is based on random particle movement. so therefore, the more particles you have in a space, the more likely they are to collide. Therefore making the reaction start up.
This theory can be proved if you compare the rates of reaction with crystals in hydrochloric acid. 'If the acid is of a higher concentration, the reaction will be quicker.'.
Also if the particles have more energy, they will be travelling faster, making them collide more frequently making the rate of reaction faster.
Variables
The factors which might affect how well the investigation will work are:
The temperature
The concentration of the acid but we stayed with the same molar throughout the experiment.
The surface area (size of the chips)
Adding a catalyst (this is possible but not for this reaction)
The mass of the carbonate (amount of chips)
Different acids.
I want very accurate results so I am going to repeat my experiment two times and take an average. I will also measure the factors, which I hope to keep constant so that I can prove they did not change and affect the experiment.
There are some factors that affect the rate of a reaction. They are: Concentration of reactants Temperature of reactants Surface area of reactants Use of catalysts Presence of light These factors affect the number of collisions of reactant particles, and this, in turn, affects the rate of the reaction. If the number of collisions per second increases then the rate of the reaction will increase.
Collision Theory
Collision theory explains that the rate of reaction depends on how hard and how
often particles collide (the amount of activation energy). The rate at which the
particles collide is dependent upon four factors, which are:
1. Temperature, 2. Concentration, 3. Catalyst, 4. Surface Area of the Particles.
Temperature affects the rate of reaction as the temperature is increased the
particles gain more energy and move at a quicker rate. As the particles are
moving quicker with more energy more collisions are likely to take place,
breaking more bonds, and therefore the rate of reaction increases.
Concentration or pressure is a huge factor in the rate of reaction because as
the reactant becomes more and more concentrated there are more particles of the
reactant packed in, per unit volume, meaning that more useful collisions are likely to occur in order to increase the rate of reaction.
Catalysts increase the number of collisions as it gives the reacting particles a
surface to stick to on which they can collide. This obviously increases the
number of collisions increasing the rate of reaction. Less activation energy is
needed when there is a catalyst involved as the rate of reaction increases due
to the catalyst.
The surface area of the particles can affect the rate of reaction as if there is
one reactant there will be a smaller surface area for the particles to collide
with and break up than if there were many smaller pieces of the reactant of the
same volume. Smaller reactants will mean more area for the particles to collide
with meaning more useful collisions.
Changes in mass could measure the speed of the rate of reaction as if the
reaction produces a gas, placing the solution on a mass balance will show the
decrease in mass, and the change could be easily measured.
The volume of the gas given off could measure the speed of the rate of reaction
as a gas syringe could measure the volume of the gas given off.
Prediction:
I predict that rate of reaction will be more rapid the smaller the
reactant. I believe that more Carbon Dioxide will be
produced more quickly in the when there are smaller reactants so there will be more surface area for the particles to react more. I feel that this will happen as the smaller the crystals the more particles of the hydrochloric acid there are packed in, therefore
the more likely it is for useful collisions to occur. As there are more
particles and more collisions, more reactions will occur and the rate of
reaction will increase.
I expect the rate of reaction to be directly proportional to the chips size. I believe that the powdered crystals will speed up the reaction as they cover a very small surface area. I also believe that there is a limit to the rate of reaction, and once
the concentration is at a certain level the rate of the reaction cannot
increase.
Fair Test:
This experiment was kept as fair as possible. The measurements were all made as
exact as possible. Each experiment was carried out under the same conditions as
to prevent a factor such as heat alter the results. The same amount of hydrochloric acid
was used in each experiment (0.4m). And the crystals weighed up to 1.5g because if some were heavier then others that means the rate of the reaction would also have been altered due to the change in surface area.
Analysis:
In this experiment we are trying to find out how surface area affects the amount of carbon dioxide produced when hydrochloric acid reacts with Calcium carbonate.
In this experiment we found out that the smaller the reactant the quicker the reaction happened. On our results it shows us that the small crystals contained more gas then the others apart from the powdered crystals which reacted to quick to even get a result. I think that this experiment was a success because we gained a set of results, which explained that different size of reactants can affect the amount of carbon dioxide produced because the collision theory took place in this experiment and had an affect on the experiment. But there was an anomaly on the graph with the small crystals as they stay about level with the other crystals and after a 120 seconds they shoot up and produce much more carbon dioxide, when the small crystal line on the graph should start off above the other sized crystals rather then rise at a random point in the graph. A reason for this could be me and my partner taking the readings wrong as our results as this would cause an anomaly such as that on the graph.
During the experiment there was proof that a reaction was actually happening. We knew this because every time we emptied out the apparatus in what the reaction was taking place we found that there was smoke coming from the apparatus. The trends and patterns that happened in this experiment was that the small chips produced the most amount of carbon dioxide in the time we gave each one and the medium chips produced more carbon dioxide then the large chips suggesting that the bigger the chips the slower the reaction and the smaller the chips the faster the rate of reaction.
Evaluation:
This experiment was successful because our results showed us that the larger the surface area the bigger amount of carbon dioxide will be made. Another experiment, which could have been done, instead which would have made an experiment were there were electrical sensors which measured the point of were it is needed to be measured to and this would eliminate human error because it would be accurate. The trends and patterns of this experiment show us that the smaller the reactants the larger the surface area and the bigger amount of C02 is produced. This was proved in our results and our graphs and was extremely important that it did. The powdered chips produced the highest amount of carbon dioxide but the reaction was too fast and we could have solved this problem by lowering the weight of powdered crystals so we could get a result and then scaled the graph.
