In this investigation I am aiming to find out the effect of acid concentration on the rate of reaction. In a chemical reaction there are four factors that affect how quickly the reaction takes; this is also known as its reaction rate: Temperature Concentration Surface Area Catalyst The reaction I will be looking at is the reaction between magnesium (Mg) and Hydrochloric Acid (HCl) 2Mg + 2HCl -> 2MgCl + H2.
I will not be looking at the effect of temperature because this variable is difficult to control, surface area is very difficult to measure and catalysts would be very expensive, therefore I have decided to do concentration as this is easy to measure and vary. To do this investigation I will get different concentrations of acid and time, using a digital stopwatch how long it takes for the acid to react with the magnesium. This will give me the reaction rate which I can incorporate into a graph and compare which other data to help me determine how acid concentration affects the reaction time.
To make the experiment as safe as possible I am going to make every effort to insure that I am wearing goggles at all times and that there is no possibility of any nearby objects obstructing me or potentially making the experiment dangerous. As the effect of acid becoming in contact with human skin can be rather dangerous I am going to remain standing throughout the whole experiment so there is a minimal possibility of acid leaking onto my lap or any other areas sensitive to acid. For this experiment, the equipment I will need to use is the following:
3 Beakers 3 Measuring Cylinders 1 Digital Stopwatch 25 1cm Magnesium Strips Hydrochloric Acid Water Once I have retrieved all the equipment I will then have all the necessary resources in order to complete the experiment. The following points discuss the steps involved in beginning the investigation: Pour x amount of HCl into 3 measuring cylinders Pour the HCl into the beakers and do the previous process, but instead with water Place a 1cm magnesium strip into the beaker and begin timing with the stopwatch.
Once the magnesium has completely disappeared stop the stopwatch and record the time Repeat the process until I have sufficient results I feel that this experiment is easy to set-up and is cheap as the equipment required is neither expensive nor hard to use. Below is a clearly labelled diagram of what the experiment will look like once completely set-up: Throughout the experiment I will be constantly changing two variables and these are acid concentration and water concentration as these are the two main factors in influencing the rate of reaction.
While I am changing two variables I am keeping the length of magnesium the same throughout as I am trying to determine the rate of reaction between hydrochloric acid and magnesium which therefore means the magnesium needs to be a consistent size otherwise the experiment would be rendered unfair. It is extremely essential that I control each variable appropriately and that the test is fair otherwise my results will have anomalies and will make the investigation unreliable.
In this investigation I am not going to have a limit on how long each test can last for as it is not important and there is no way I can predetermine the time it will take to do each of the tests. Due to the drastic effect of anomalies and the importance of reliable and correct data I feel it is apparent that I need to do each test five times and then work out an average of all the results from the five tests which I can then display in a graph.
This will mean in total I will have done twenty-five tests at the end of the experiment which is a sufficient amount in order to make the results extremely reliable and correct. I feel in any experiments you do you need a wide range of results as it makes it easier to find out any patterns and evaluate afterwards as you will have stronger evidence. I predict that the most concentrated acid will give the fastest rate of reaction because from my scientific understanding I know that for a reaction to occur, two or more molecules of different elements or compounds, for example Mg and HCl have to collide.
From the previous statement it suggests that the more molecules present the more susceptible a reaction will occur. Consequently as there are more collisions, the reaction will go faster and the rate of reaction will be higher. To help me develop my prediction I have used various sentences from the webpage, www. chem4kids. com/files/react_rates. html. Now that I have developed a prediction based on theoretical knowledge and information from other sources I now have the ability to develop a graph displaying the likelihood of the results.