The Effect of Hydrochloric Acid on the Rate of Reaction with Magnesium Ribbon

The Effect of Hydrochloric Acid on the Rate of Reaction with Magnesium Ribbon
Introduction: The equation below shows the reaction between Hydrochloric acid and Magnesium ribbon. As you can see, hydrogen is one of the waste products of the reaction. To test for hydrogen we can collect the gas is a test tube and expose it to a lit splint, if hydrogen is present then the gas will go ?pop?, it is known as ?The squeaky pop test?. [image]2HCl + Mg MgCl + H [image]Hydrochloric acid + Magnesium Magnesium Chloride + Hydrogen I have decided to investigate how different concentrations of Hydrochloric acid affect the rate of reaction when exposed to Magnesium ribbon. I have chosen this method to use as I think it is a very simple way to collect the necessary data required to answer the question that I am investigating. Prediction: I think that the more concentrated that the acid is, the quicker the reaction will take place, and the less concentrated the acid is the longer the reaction will last. For a reaction to occur the reactant particles must collide. Only a certain fraction of the total collisions cause chemical change; these are called successful collisions. The successful collisions have sufficient energy (activation energy) at the moment of impact to break the existing bonds and form new bonds, resulting in the products of the reaction. Increasing the concentration of the reactants and raising the temperature bring about more collisions and therefore more successful collisions, increasing the rate of reaction, therefore producing a faster reaction.
Preliminary Work: For the preliminary work I have followed the method that I will use in the final experiment. I have experimented with different amounts of magnesium ribbon to find out which quantity will be the most efficient to use. If too little magnesium was used, the reactions would be too quick and would be very difficult to record the results, and if too much magnesium was used then the reaction would last for too long. I came to the conclusion that 5cm of Magnesium ribbon would be a sufficient amount to use, as it didn?t react to quickly or to slowly to record the results. 50ml of HCl 10ml of HCl 40ml of H O 4cm of Magnesium 13.23sec 9:16.34sec 5cm of Magnesium 16.55sec 13:01.88sec 6cm of Magnesium 22.59sec 20:42.04sec Apparatus to be used: o Magnesium ribbon o Hydrochloric acid (2 moles) o 100ml Beaker o Stop watch o Tap water o Measuring cylinder Method: In the actual experiment I will follow this method. First of all I will cut the Magnesium ribbon into six pieces of 5cm in length. Next I will put each piece into a different concentration of acid and time how long they take to disappear. The different concentrations of acid that I will use are: o 50ml HCl 5:0 100% acid o 40ml HCl + 10ml H O 4:1 80% acid o 30ml HCl + 20ml H O 3:2 60% acid o 20ml HCl + 30ml H O 2:3 40% acid o 10ml HCl + 40ml H O 1:4 20% acid To make the results accurate, fair and reliable we will use the same amount of magnesium ribbon each test and an equal amount of liquid. To keep the quantities of acid and water accurate throughout the experiment I will measure the liquid using a measuring cylinder. Using a ruler will ensure that the lengths of magnesium ribbon are the same. These variables need controlling as if they are not accurate the test will not be reliable. Variable to be changed Variable to be kept the same Quantities of acid Amounts of magnesium Ribbon Quantities of water Volume of liquid in total used Safety Measures: Throughout this investigation, whilst using any concentration of acid I will wear safety goggles to prevent any damage to my eyes. Results: Amount of Acid + water Time taken (sec) #1 Time taken (sec) #2 Time taken (sec) #3 100% acid 19.53 20.09 18.55 80% acid 28.59 30.65 30.21 60% acid 44.34 42.73 45.06 40% acid 02:26.1 02:45.6 01:59.9 20% acid 16:39.4 15:55.7 16:44.6 Amount of Acid + water Time taken (sec) Average 50ml HCl 24.79 40ml HCl + 10ml H O 38.88 30ml HCl + 20ml H O 58.87 20ml HCl + 30ml H O 164.03 10ml HCl + 40ml H O 1206.67 [image] Analysis: The results from my graph show that with an increase of acidic concentration, the time for the reaction between the Hydrochloric acid and Magnesium ribbon to finish decreases. On my graph the 20% acid volume shows that the reaction lasts for a long time (1026.37secs) compared to the 100% acid volume, which lasts for a very short amount of time (24.79secs). The higher concentration of acid completes the reaction quicker than a lower concentration because there are more reactive particles making contact with the magnesium. The more particles that hit the magnesium will cause the reaction to happen faster. The prediction that I made backs up my results. I predicted that the higher the concentration of acid would make the reaction quicker, this is what the table and graph show. Evaluation: In this investigation, I found that I had no anomalous results. I know this because my graph shows a smooth line of best fit and passes through all points. If I had had any anomalous results, then they may have occurred through inaccurate time recording, magnesium measurements or acid concentration. The only way to overcome these anomalous results is to be very accurate with any measuring or recording. My graph and table show accurate results as they are all realistic, close together. The results are also reliable as they were taken fairly and as accurate as possible, all variables were controlled and checked. To investigate the question further, different concentrations of acid could be used, or different amounts of magnesium ribbon. Also, a different method could be used, for example; measure the amount of gas that is given off from the reaction or even the different rates of reaction at different temperatures.

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