Method:
First of all I am going to test the rate of reactivity of the calcium carbonate (limestone chips) at room temperature =27°c, this is because it was a heated room.
I measured 6 0.50grams of limestone chips and added individual 0.50 grams into separate boiling tubes with 10ml of Hydrochloric acid which was measure using a measuring cylinder. I then added the acid into the boiling tube with the limestone chips and started the stop clock straight away. For the molarities between 0.25 and 1.00 molars we measure the amount of carbon dioxide produce by the experiment from the calibrated collecting tube every 15 seconds until we reached 120 seconds which is a total of 8 checkpoints. After each time I will throw away the limestone chips because they cannot be used again as some reactant will have been used up. To get the best possible results I am going to test it 2 separate times to enable me to judge the amounts of gas produced fairly and decide if they are correct and accurate. I shall then fill a calibrated collecting tube with water and put it inside a beaker with water surrounding it. The calibrated collecting tube needs to be surrounded by water so that no water shall be lost from the collecting tube. I will then put the Hydrochloric acid into a boiling tube and place the boiling tube into a calibrated collecting tube which is surrounded by the water inside a beaker. By varying the molarities of the acids it should show me more accurately the results of how the concentration of Hydrochloric acid affects the rate of reaction.
Safety
- When using the acid handle it must be handled carefully and with responsibility because it is a harmful product if it comes into contact with the skin.
- The tube attached to the boiling tube must not be shaken to hard as it may crack resulting in broken glass which is potentially dangerous.
- Goggles must be worn as acids are very dangerous substances and can cause major skin irritation or burns and can damage eyes if squirted into the eye.
- After the experiment has been completed hands must be washed thoroughly in case any acid residue may have come in contact with the skin unnoticed.
Fair testing
To ensure that the experiment is fair the volume of the concentrations must be kept equal. The mass of which the limestone chips are weighed at must be equal in this case we made all of the limestone chips 0.5 grams.
I think that the stronger the morality of the concentration is the faster that the limestone chips shall dissolve.
To create a fair test certain aspects of the experiment will have to be kept the same
To keep it a fair test, the variables need to be kept the same to prevent getting the wrong results. The temperature of the acid must be equal throughout the experiment to gain the correct rate of the reactions with the limestone chips. The mass of the limestone Chips and volume of the HCL solution needs to be kept equal to help me attain the most accurate results I can as some of them may have a larger or smaller surface area for the acid to react with. If the limestone chips were 0.20 grams heavier they would have a larger surface area than the previous chips the results would be wrong because the acid has a larger surface area to react with, therefore the time it would have taken would be more than it should be in comparison to other results. If it were compared to the smaller chips the time would be less because of it having a smaller surface area for the reaction to take place. The Hydrochloric acid cannot be used again after the reaction otherwise the acid will be less strong to act on the limestone chips and some may have been evaporated due to heat from the chemical reaction.
When I am reading the calibrated collecting tube for results I need to be accurate in the amount I have observed and recorded because it could affect my results.
As I shall be varying the concentration of the Hydrochloric acid solution it will allow me to attain a set of varied results from which I may understand rates of reaction and therefore create a conclusion to my experiment. If any of the variables below are not kept constant it would mean it would that the experiment would be regarded as unfair. The experiments were al exposed to the same moderation of heat which was the room temperature the room temperature was 27 degrees centigrade.
To keep the potential rate of reaction equal the limestone chips have all been weighed at 0.50 grams (2d.p.) and shall be suspended in 10 ml of Hydrochloric acid solution at varying molarities.
The volume of the solution that the limestone chips are kept in must be fair. The must be 10 ml. I am also going to use the same balance to weigh my limestone chips. This is because the measurements may slightly vary between different scales.
Also another variable is heat therefore to control the heat variable we must do the experiment in one day instead of stretching it out over numerous days, therefore results attained are more accurate as the room temperature is equal for all experiments. To get accurate results we have decided to suspend limestone chips into each solution twice which will allow us to create an average and therefore gain more accurate results. Certain variable must also be kept equal which shall be discussed in further detail below.
VARIABLES
In this experiment I have the choice to change certain variables to see what effects it could have on calcium carbonate. I am changing the concentration in molars of the Hydrochloric acid to investigate the rates of which the Calcium Carbonate reacts with it, and to discover what concentration of Hydrochloric acid dissolves the calcium carbonate at the fastest rate, and therefore releases carbon dioxide. The other variables I could choose from to investigate are:
- Size of the Calcium Carbonate Chips.
- Concentration of the Hydrochloric acid
- The temperature of the acid.
- Amount of limestone chips and Hydrochloric acid.
- Size of conical flask
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The temperature of the acid - The reaction gets its energy from the heat it is working at, the heat gives the reaction potential energy, then this energy is given to the particles and therefore they begin to collide, as the temperature increases as does the amount of energy there is to collide with each of the different substances of particles which will collide the fastest. If the temperature is low there would be less energy given to the particles for more collisions per second and the reaction would begin slowly. Therefore the experiment will be done one after the other on the same day allowing the room temperature to be equal for all solutions the temperature was 27 degrees centigrade.
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Surface area of the conical flask - If the flask has got a small base, the acid and the limestone chips will be more condensed together, meaning that the acid is closer to the chips surrounding it thus covering a larger surface area of particles. With the chips closer together it means that the collisions will occur more often because the particles will not loose their energy travelling to another particle otherwise the collisions will be less (based on collision theory).
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Size of calcium carbonate chips - The size will determine the rate of the reaction, if the chips are small like powder, then they would have a larger surface area, therefore the rate would speed up because the bonds would be easier to break up because more of the acid particles will have more access to more of the powder which would make it faster. Therefore I have decided to create a universal mass of 0.5 grams of limestone chips for all solution allowing it to be a fair test. If the chips were bigger, they would have a smaller surface area overall, this means that the acid will have less area to act on to dissolve.
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Concentration of the Hydrochloric acid - If the acid is diluted with water it would make it weaker and also slower to react with the chips of calcium carbonate and because there are less particles of the reactant between the water molecules, which would have enabled it to make more collisions and therefore react quicker. Whereas if the solution has a stronger concentration with less water or none at all it would react at a faster rate, this is because there will be more of the particles reacting and colliding at a more faster rate than a solution with a weaker concentration and larger surface area.
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Amount of limestone chips - If the amount of chips is more than the amount of acid it means that the chips will have less particles of acid between their particles, therefore making an unequal amount of each product, which will slow down the reaction rate if there were to be more chips as they are the reactants. If there were fewer chips compared to the acid the reaction will be faster because more of the acid will be present for each separate chip and more of the surface area will be covered which means more of the acid will dissolved.
Equipment/Apparatus
- Conical Flask
- Measuring Cylinder
- Stop clock
- Beaker
- Calibrated collecting tube
- Calcium Carbonate (limestone Chips 3 grams in total)
- Hydrochloric acid (140ml in total)
- Goggles
- Weighing Scales (2d.p.)
- Boiling tube
Analysis of Results and Conclusion
I have worked out the average because then the results will be judged properly and will be easier to add into a graph to compare between each temperature. From the results I am able to tell that my prediction about the stronger the reaction the faster more CO2 would be produced in a shorter period of time. The trends in the results also prove this. The graph results were therefore not surprising in any way. The results that we gained were therefore related tot the collision theory which is stated in the hypothesis section of the coursework.
In this experiment my aim was to find out what factor changes the rate reaction between Calcium Carbonate reacting with the Hydrochloric acid which I managed to succeed in doing so. I recorded the rates of the varying concentrations and their effects. My prediction matched and concluded with my results, as you may verify by observing the data graphs. I have proved that greater concentrated the HCL concentration is the faster the limestone chips react and produce a larger quantity of gas in a shorter amount of time. I noticed that during the experiment the amount of gas it was producing would slow down, this is because the activation energy which it had been given at the start gave it a ‘boost’ and at this point it would have been the fastest, until it had worn off which would at approximately half way through the allotted time.
In the graphs, I saw definite patterns; they all have a positive correlation which shows that they are following the same trend.
Evaluation
The experiment I think went very well and I managed to get all the information I needed which I am very pleased about. At first I was aiming to increase the concentration up until 2.00 molar but the allotted time we had for the experiment was not enough to complete the task.
The rates of reaction between the two substances were quite accurate as we measure each molar twice allowing us to create an average and therefore more accurate result. An improvement is that the calibrated collecting tubes may have been calibrated using on a larger scale for example instead of whole readings such as 6,7 or 8 there should have been 0.5 measurements allowing us to read of the amount of gas produced more accurately instead of estimating whenever the gas was between numbers.
