Investigating the Effect of Varying Concentration on the Reaction between Magnesium Ribbon and Hydrochloric Acid

Investigating the Effect of Varying Concentration on the Reaction between Magnesium Ribbon and Hydrochloric Acid
This investigation is being carried out to discover how the concentration of Hydrochloric Acid (hcl), combined with Magnesium Ribbon (Mg), diluted with Water (H20) will affect the rate of reaction. The rate of reaction will be measured by the amount of hydrogen gas (H2) released. This will be measured every 10 seconds during the experiment. Each time the experiment is conducted, the amount of hcl provided for the reaction to occur will be varied. The chemical equation for this investigation is: Mg (s) + 2HCl (aq) à MgCl2 (aq) + H2 (g) Also in words as: Magnesium + Hydrochloric acid à Magnesium Chloride + Hydrogen Preliminary Before I conducted the real experiment, I conducted a preliminary experiment. This is where I varied the concentration and the length of the magnesium ribbon. The aim of this was to find the suitable length and concentration of the reactants. I found this very useful. I tried suing 3cm magnesium ribbon but found that the experiment went a lot slower because there was less magnesium to react. I found this ?boring?. In an interest to speed up the reaction I used 5cm magnesium ribbon. Background Knowledge In chemistry, there are many possibilities of reactions occuring. They occur at different speeds. This speed is known as the (ror) Rate of Reaction. Precipitation reacts quickly but other reeactions like fermentation react a lot slower.
There are many other factors which affect the rate of reaction. These are called variables. In chemistry there are 3 types of variables: independent variables, dependant variables and constant variables. Examples of variables are: light, surface area, catalysts, temperature, concentration and pH. The increase in a ror is explained by collision theory. Collision theory Collision theory is about the collision of particles in an experiment. This is measured by ror. (See Above). If the reactants in an experiment re heated during the experiment the contents of the reactant, (the particles), will move around faster and have a greater chance of reacting in a shorter period of time. For the collision to take place, the particles must collide with enough amount of activation energy for a reaction to occur. If there is not enough activation energy, then particles will collide and bounce off each other. Prediction I predict that the higher the concentration of hydrochloric acid, the faster the rate of reaction, this will cause gas to be given off faster. I.e. hydrogen gas will be expelled faster as one of the products of the reaction. I believe this because many chemical reactions occur when the concentration is increased. This is because there are more collisions in a shorter space of time. (See: Collision Theory above). Apparatus ? Magnesium ribbon to make the experiment work! ? 2 Measuring Cylinders ? Conical Flask ? Scissors to cut magnesium ribbon ? Ruler (30cm) to measure Magnesium ribbon ? Goggles to protect my eyes ? Delivery tube from gas syringe to conical flask ? Clamp stand to hold gas syringe ? Gas syringe to measure hydrogen gas expelled ? Water to make different concentrations ? Stopwatch to time how long the reaction takes to finish ? Dilute HCl Safety Throughout this investigation, may safety precautions will be taken. The investigator will take great care when handling these chemicals and will, at all times, wear the following safety item: ? A pair of safety goggles to protect my eyes from any spilt or dangerous acids that I will be handling ? I will also be keeping all test tubes in a test tube rack s that they do not roll off the desk, fall onto the floor and empty their contents where it could potentially harm someone conducting their investigation. My tie will also be tucked into my school shirt due to safety precautions. E.g. if I lean over to get a piece of required apparatus over a burning flame by accident, my tie may catch fire and is therefore a fire hazard to conduct these types of investigations with a loose tie! Factors affecting the experiments -??????????????? I will never be able to keep the factors 100% the same for each experiment conducted in this investigation, but I can go to some measures to ensure that main factors affecting the rate of reaction in this experiment. The factors that I can control and will not be varying are: ? Temperature that the investigation is conducted in ? If the gas syringe is level to the desk, to make sure it is a fair test. This will affect the experiment if not kept the same. Diagram Method 1. Set up the apparatus as shown in the diagram. 2. Make sure that the gas syringe is level with the desk; this may affect the experiment if not carefully kept level. 3. Cut a strip of magnesium of length: 5cm 4. Measure the amount of HCl using a measuring cylinder. 5. Pour the acid into a flask 6. Reset the stop clock as necessary 7. Drop the Mg into the conical flask and at the same time start the stop watch. 8. Record the results as the amount of gas is acquired, repeatedly at equally spaced intervals. 9. For accuracy repeat each experiment twice. From the two readings, I will create one set of results. This will be the average of the original two. 10. I will repeat each experiment for the different molarities. 11. I will then produce the results with the following headings: Concentration Time taken (s) Hydrogen gas given off After creating my results table, I will draw a graph, clearly labelled on the x axis and the y axis, also containing a line of best fit and a title. From this graph I will produce another results table with the ror on it, with the headings: Molarity (M) Amount of Hydrogen Gas Produced (cm³) Time Taken (secs) Rate of Reaction to 2 decimal places (cm³/s) To work out the rate of reaction, I will take the volume of Hydrogen gas produced and divide it by the time taken to produce it. With this I will draw another graph to show the rate of reaction. The two graphs will show the effect of varying the concentration of HCl on the ror, with Mg. I will then write a conclusion and analyse the information shown in my graphs, then evaluate my conclusion. Results === Concentration Time taken (s) Hydrogen gas given off 1.50M 5 10 1.50M 9 20 1.50M 12 30 1.50M 16 40 1.50M 20 50 1.50M 24 60 1.50M 34 70 1.50M 48 80 The above results are of 1.50 Moles. I have observed no anomalies. All of the results are approximately in a straight line on the graph that I have produced. However the graph is should have curved upwards at the end. This should have happened due to collision theory. (See page 2). Concentration Tim taken (s) Hydrogen gas given off 1.75M 4 10 1.75M 8 20 1.75M 12 30 1.75M 15 40 1.75M 18 50 1.75M 22 60 1.75M 27 70 1.75M 36 80 The above results are of the molarity: 1.75 Moles. These are approximately in a straight line on my graph. However, these are a lot higher compared to 1.50 Moles. This indicates that the reaction sped up as time progressed. This indicates that the rate of reaction is still constant but has increased dramatically. This is due to the concentration of the HCl being higher. If there are more HCl particles then the rate of reaction will be affected. I.e. Increasing. Concentration Time taken (s) Hydrogen gas given off 2.00M 3 10 2.00M 5 20 2.00M 8 30 2.00M 9 40 2.00M 12 50 2.00M 14 60 2.00M 17 70 2.00M 22 80 The above experiment was conducted with 2.0 Moles of HCl. These results also go in a straight line but do curve upwards at the end. This fits my prediction. Obtaining Evidence Results I repeated each experiment twice to guarantee increase accuracy and drew graphs to show my results. Table of results I drew up tables of my recorded results to show the general situation of the reaction. Anomalies I did not incur any major anomalies Analysis and Considering Evidence From these experiments that I have conducted, it is clearly shown that as the molarity of the HCl increases, so does the rate of reaction. Graph to show Average time taken to produce 50cm³ of Hydrogen gas using a range of different molarities From the graph I can see that as the molarity of the HCl increases, so does the rate of reaction. This also means that as the molarity of the HCl increases, the Time Taken to for the reaction to expel the Hydrogen gas decreases. As the molarity of the acid increases, this means that the number of hydrogen and chlorine particles in the solution, is more concentrated/less diluted. This creates a higher possibility of the particles reacting. Therefore this speeds up the reaction. The green colour on the graph (2 Moles Hydrochloric Acid) is not as steep as the grey line on the graph (1.5 Moles). This shows that as the rate of reaction increases, the gradient decreases. When the graph was plotted, I noticed some minor anomalies; however they were not major so I did not note them down as official major anomalies. I discovered that there were minor anomalies as they did not fit the general curve as I had predicted. This may have occurred because I may not have measured the right amount of Magnesium or I may not have mixed the HCl mixture well. Graph to show Rate of Reaction of varying concentrations of Dilute Hydrochloric Acid This graph is explained by its title. This graph shows the rate of reaction (ror) on the Y-axis and the Hydrogen gas expelled on the X-axis. All of the ?curves? on the graph are all of the same shape, however, the curves are in different positions on the graph. This shows the rate of reaction. The higher the curve, the higher the rate of reaction. This indicates that the 2.0 Moles solution (green line) has a higher rate of reaction than the 1.5 Moles solution (grey line). This I because the 1.5 Moles solution?s content of particles has a lower concentration of HCl particles. Vice Versa with the 2.0 Moles solution. Evaluation After observing my results, I found that they were very accurate, but did have minor anomalies. I have not noted these anomalies down as hey were very minor. However this does not mean that I have ignored them. If they were major anomalies and affected my smooth curve, I would have noted them down and explained why I have received these errors in my investigation. This explanation would also include how I would prevent these from occurring in future experiments. If I had incurred major anomalies, I suspect that they would be the cause of experimental errors that may have occurred during the investigation. To ensure that I have acquired accurate results, I repeated each experiment twice in this investigation. I then drew two graphs to accurately present my results in a different form, rather than a table. This is because I can now compare results with each other easily and I can notice anomalies a lot more easily. If I were to repeat this entire investigation, I would change many aspects of it to improve accuracy of results. I would ensure that my results would be recorded exactly on time, because I have learnt from this investigation that even the slightest misreporting can cause minor anomalies and sometimes major anomalies. If I repeated my entire investigation, I would experiment with a wider range of moralities and a larger time scale for the reaction to take place. I would however need a lot more time for this. I would, if I had more time, repeat each experiment twice instead of 3 times. Due to time restrictions, I could not do this. During my experiment I should have been more careful towards the factors that would be affecting my experiment rather than the ones that don?t affect my experiment as much. I would keep the moralities the same if I repeated this experiment because I found from this investigation that the moralities used were exactly the right ones for the rate of reaction that I had been recording. Before I started my investigation I had the choice of doing this investigation by either varying the temperature or by varying the concentration. I chose concentration because I found that temperature might not be very accurate, due to many factors. I.e. Room temperature affecting the experiment.

Investigating the Effect of Varying Concentration on the Reaction between Magnesium Ribbon and Hydrochloric Acid 9.1 of 10 on the basis of 3792 Review.