Acid Marble Chip Reaction example essay topic

Aim: Investigate what affects different temperatures of hydrochloric acid have on calcium carbonate. Background Information: For a reaction to take place, collisions must occur between the particles. If the collisions occur more frequently then the rate of reaction will increase. The rates of reactions can be altered in many ways. The variables are: The size of the particles of a solid reactant The concentrations of reactants in solution The temperature The presence of light The addition of a catalyst A catalyst is a substance that can alter the rate of a chemical reaction without being used up in the reaction.

Equation: Calcium Carbonate + Hydrochloric acid Carbon Dioxide + Calcium Chloride + Water CaCO (s) + 2 HCL (aq) + CO (g) +CaCl (aq) +H O (I) Prediction: In this experiment, I am going to see how temperature affects the reaction rate between marble chips (calcium carbonate) and hydrochloric acid by timing the release of carbon dioxide in the reaction. I predict the higher the temperature, the faster the reaction rate. This is due to the kinetic theory. The more heat that is given to matter, the faster the particles move. This happens in the acid, so the faster the particles move, the faster the reaction rate due to more successful collisions between the marble chips and the acid which is called the collision theory.

In order for a chemical reaction to occur, molecules of different substances must collide with each other at a certain speed. Since a temperature increase causes molecules to move faster, collisions between molecules will be more frequent and will have the necessary speed to start a chemical reaction. This allows for the increase in the rate of reaction. To start a chemical reaction, a minimum amount of kinetic energy is needed. The minimum energy needed to start any chemical reaction is called the activation energy. Whether a chemical reaction is endothermic or exothermic, energy is required to initiate the reaction.

Since temperature is really a measure of the average kinetic energy of the molecules of a substance, a higher temperature translates into higher kinetic energy which leads to faster moving molecules. Since the molecules are moving faster, they have a higher chance of successfully colliding and completing a chemical reaction. Thus, a higher temperature allows for a faster rate of chemical reaction. The size of the chips used makes a big difference. This is because the two types of molecule can only bump into each other at the liquid solid interface, so the larger the surface area of the solid, the faster the reaction will be. Smaller particles have a bigger surface area than larger particle for the same mass of solid.

Therefore the size of the chips will have to have the same mass and (as accurately as can be) the same surface area. We will use preliminary experiment to decide what size chips to use. Preliminary Experiment: To help me plan out an adequate experiment and to find a suitable reading range, I will do a small preliminary experiment. I was unsure what size the marble chips used should be to give an accurate reading because if a solid reactant is broken down into smaller pieces the rate of reaction increases. The speed increase happens because smaller pieces of the same mass of solid have a greater surface area compared to larger pieces of the solid.

Therefore, there is more chance that a reactant particle will hit the solid surface and react. The diagrams below illustrate the acid - marble chip reaction: From common sense we realised that the reaction using calcium carbonate powder would be much too fast to record accurately because there was a very large surface area. This would mean that the particles would collide very vigorously and quickly. We decided to test the small, medium and large calcium carbonate chips and did the biggest range of temperatures that we could carry out in the laboratory safely, which was 25 C to 60 C. Preliminary Method: Set up the retort stand with a clamp on it. Clamp the gas syringe horizontally. Weigh out six lots of 0.9 g marble chips, two lots of small chips, two lots of medium chips and two lots of large chips on a balance.

Measure out six lots of 50 cm^3 1 mol dm ^3 hydrochloric acid in measuring cylinders Take one of the 50 cm^3 hydrochloric acids and pour into a conical flask. Heat up the hydrochloric acid to the desired temperature (3 at 25 C and 3 at 60 C) on the Bunsen burner. Quickly put one lot of calcium carbonate (preferably small first) into the heated hydrochloric acid and connect the conical flask to the gas syringe which has been clamped in a horizontal position As soon as it is connected start the stop clock and stop it again when 20 cm^3 has been collected Clean out the conical flask and repeat the experiment again until all the designated experiments have been completed. Safety: I will wear goggles due to the fact that I am handling acid because it is very corrosive and dangerous. Results: 25 C 60 C Small Chips 67, 69 0.03, 59 Medium Chips 83, 89 0.06, 22 Large Chips 100, 50 0.10, 82 The preliminary showed that the experiment worked. I have decided to use medium chips because small chips are quite fast and so our reaction time would make the results less accurate.

Using the large chips would also be fairly inaccurate because getting the same weight of large chips, whilst keeping roughly the same amount of surface area would be very difficult. The results from the preliminary fit in with my prediction although more readings are needed. Experiment. Equipment Goggles Retort Stand Boss and Clamp Gas Syringe (with the bung and tube attached to it) Conical Flask Electronic Balance Measuring Cylinder Bunsen Burner (and gas supply) Heat Proof Mat Gauze 400 cm^3 Hydrochloric Acid 8 lots of 1.00 g marble chips (two chips per 1.00 g, with the same surface area) Thermometer Stopwatch Variables: I will try to make it as fair as possible by trying to take the most accurate measurements at the most precise times. Make sure that the mass of Calcium Carbonate is precise and that in all the experiments done it is the same, or at least as close as possible as this will ensure better results. Make sure that there is the same amount of Hydrochloric Acid in each experiment.

If I do this I think my Hypothesis will be accurate. I will need a stand and I will need clamps to fasten the gas syringe. I will of course need a gas syringe that is intact with no leaks. I will need the rubber tube attached to the cork to fasten the gas syringe to the test tube. The test tube needs to be clean to avoid any other chemicals interfering with my experiment.

I will also need a test tube holder since I will be keeping my solution still. I need an accurate timer. Then, of course I will need my pen and paper to record my results. There are many factors that will affect how well my experiment will work. The only variable I will change is temperature. If the test tube isn't clean then whatever chemical is lining it could affect the outcome of the experiment by changing the reaction so it needs to be thoroughly cleaned before I use it.

Also I have to make the decision whether I'm going to keep the test tube still or whether I'm going to shake it. This is an important choice, as if I shake one of the test tubes then I'll have to shake all of my experiments. However, I'm choosing to keep the test tube still. Another factor that is very important is whether or not the gas syringe is leaking. If it is leaking, then my results cannot be accurate. Also, if it is stiff then it might jump form one place to another without sliding.

If the surface area of Calcium Carbonate differs too much in between experiments, then there is no way that they can be accurate. I have chosen to use medium chips only. The amount of Hydrochloric Acid (50 cm^3 in my case) has to be constant also making sure that it is 1 mol dm ^3. If the mass of the Calcium Carbonate varies then the Hydrochloric Acid will have more, or less, surface area to react on which would change my results greatly. Same for if I have more Hydrochloric Acid in my beaker, then the Calcium Carbonate will have more to react on. Diagram: Method: Put goggles on because the corrosive acid is very dangerous.

Set up the retort stand with a clamp on it. Clamp the gas syringe with the cork attached to it horizontally. Make sure this is done on a flat and stable surface. Weigh out the 8 lots of 1.00 g medium marble chips on the electronic balance.

Choose two chips to make up the 1.00 g total and make sure every lot has (as accurately as possible) the same surface area. Measure out 8 lots of 50 cm^3 1 mol dm ^3 hydrochloric acid in measuring cylinders. Take one of the 50 cm^3 hydrochloric acids and pour into a conical flask with a thermometer in it. Heat up the hydrochloric acid to 25 C (put it on the gauze that is on the metal tripod) over the Bunsen burner. Make sure the Bunsen burner has a heat proof mat underneath it for safety. The following two steps need more than one person to carry it out because there are three jobs that need to be done almost at exactly the same time.

Quickly put 1.00 g of medium marble chips into the heated hydrochloric acid and connect the conical flask to the gas syringe, by putting the bung (adjoining the gas syringe) in. As soon as it is connected start the stop clock and stop it again when 20 cm^3 of gas has been collected. Quickly detach the gas syringe and put in thermometer. Record the temperature. Clean out the conical flask thoroughly and repeat the experiment, heating the hydrochloric acid to 30 C, 35 C, 40 C, 45 C, 50 C and 60 C. Repeat the whole experiment twice more to obtain more accurate results. Fig 1/Time (s) 3 sig.

Fig 1/Time (s) 3 sig. Fig Average (s) 3 sig. The thermal energy is transferred into kinetic energy and the increased kinetic energy makes the particles increase their speed and they collide successfully a lot more. This leads to a greater amount of successful collisions, which leads to an increase in the reaction rate.

I used the results obtained to plot five graphs. Two of the graphs, one with all the results and one with the averages, plots the time it took to fill 20 cm^3 of a gas syringe with carbon dioxide, against the starting temperature of the hydrochloric acid. The graphs show that as temperature rises, the time taken for the reaction to take place decreases. The higher the temperature, the more kinetic energy the particles have. More kinetic energy makes them move through the solution more rapidly and as they move faster they collide more often and more vigorously. A greater amount of vigorous collisions leads to a greater number if successful collisions.

The more successful collisions leads to the reaction taking place in a smaller amount of time. Temperature is a measurement of thermal energy and thermal energy is transferred into kinetic energy. Therefore an increase in temperature leads to an increase in reaction rate. This fits in with my hypothesis. The graph shows a relatively smooth curve, which starts off steeply and becomes much gentler as the temperature increases. This is because the reaction starts very slowly at the beginning because the temperature is not high.

This happens because there is less thermal energy to be converted into kinetic energy to make the particles move faster and vibrate more vigorously. Therefore there are few successful collisions and not much carbon dioxide is given off. However, as the temperature increases, the curve gets more gentle as there is of less of a reaction time difference between each of the temperatures chosen and the reaction rate becomes more rapid. This is because of the kinetic and collision theory explained above. The line of best fit would never go passed the line y = 0 because a reaction is never instantaneous. The reactions carried out at 50 degrees and 40 degrees, by error of about 5 seconds, were out from the line of best fit.

Although they are only out slightly, they can be explained because they were carried out on separate days from the rest of the experiment. We may have used chips less surface area because they took longer than the other reactions in the experiment. This is the most likely reason, as we could never accurately have the same surface area on each chip throughout the experiment. The third and fourth graphs show the rate of reaction. They plot 1/Time against beginning temperature (one showing the averages and one showing all the results).

It is fairly accurate as all apart from one temperature plotting fits into the line of best fit. However, the error bars at 60 C are very large and so this shows that the reading was very inaccurate. As the temperature increases, it seems the error bars do get bigger so this would imply it is harder to take readings at higher temperatures. This could be because the reactions are taking place quite fast and the human reaction time is not enough to record the time very accurately. It may also be because we got more careless measuring out the right weight and as accurately as possible, the same surface area. This could have been because the experiment was rushed for time toward the end.

The beginning temperature was 25 C. The rate of reaction was lower than expected and is not inline with the line of best fit. This may be because we used chips with bigger surface areas than the others in the experiment. We may have also been quite irregular because it was the beginning of the experiment and we had not got into the rhythm of carrying out the last few crucial stages in the method quick enough. Overall the graphs show a definite increase in the rate of reaction as the temperature increases as I expected and stated in my hypothesis. The last graph plots the beginning temperature against the finishing temperature. This shows that the experiment is exothermic reaction.

Chemical bonds are forces of attraction between the atoms or ions or molecules in a substance. To break these bonds, energy must be supplied. When bonds are created, energy is given out. In a chemical reaction, bonds are broken and new bonds are made. The energy given out when new bonds are made is greater than the energy taken in to break the old bonds therefore the temperature increases after the reaction has taken place. The accuracy of this part of the experiment is shown in the graph.

The temperature before and after the experiment are proportional to each other. The experiment is quite accurate as the error bars are fairly minute, each being a degree (or not much more) out from one another. All the temperatures apart from one (40 degrees) go through the line of best fit. The possible reason why this is out by a degree is because I could have let the solution cool slightly before measuring it.

Although the experiment was carried out quite successfully, there were a few anomalous results. This should be overcome by taking much more care in doing the experiment. Much of the anomalous results could be improved by using small marble chips because the surface area would have been a lot closer (i.e. each set of chips would have the same surface area) and more accurate. Although I wrote we were not going to stir or shake the acid, sometimes we did because of our natural instinct and forgot. This could have altered the experiment because it would have sped up the reaction. Inaccuracy may have also been caused by the fact that the beginning temperature may have altered before the reaction took place, whilst moving the conical flask from the Bunsen burner to the gas syringe.

This could have been improved be using a water bath to heat up the acid instead. This way, I could also heat it at the same temperature throughout the beginning of the reaction. Extension: There are many possible extensions to this experiment. We could change the different variables, for example Concentration Size of the particles of the solid reactant The presence of light The addition of a catalyst A straight forward experiment using thiosulphate solution and hydrochloric acid is one way in which the rate of reaction can be measured in relation with the concentration.

Method: Measure 50 cm^3 of sodium thiosulphate solution (40 gmd-3) in a measuring cylinder. Pour it into a 250 cm^3 conical flask. Keep this measuring cylinder for the thiosulphate only. Mark a black cross on a piece of paper and stand the conical flask over the cross. Using a measuring cylinder, take 5 cm^3 of 2 mol dm-3 hydrochloric acid. Keep this measuring cylinder for acid only.

Add the acid to the thiosulphate solution. Start the stop clock and give the solution 1 swirl. Watch the cross. Time how long it takes for the precipitate of sulphur to become dense enough to hide the cross. Wash out the flask immediately, taking care not to breathe in the fumes of the sulphur dioxide gas. Repeat the experiment with each of the following solutions in the table: Volume of the sodium thiosulphate (cm^3) Volume of water (cm^3) Concentration of thiosulphate solution (g dm-3) 50 0 40 40 10 32 30 20 24 20 30 16 10 40 8 This would show how the concentration affects the rate of reaction.

I would expect to find that because the concentration of any reactant in a solution is increased, the rate of reaction is increased. Increasing the concentration, increases the probability of a collision between reactant particles because there are more of them in the same volume. Therefore the greater the concentration, the faster the reaction rate.