To Investigate The Effect Of Concentration On The Rate Of Reaction Of Magnesium And Hydrochloric Acid.

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To Investigate The Effect Of Concentration On The Rate Of Reaction Of Magnesium And Hydrochloric Acid

        In my experiment I aim to look at the effect that different concentrations of hydrochloric acid have on the rate of reaction. I will carry out a pilot and modify it for my final experiment; I will then evaluate my work.

        The word and symbol equations for this experiment are:

Magnesium + Hydrochloric Acid      Magnesium Chloride + Hydrogen

             Mg      +               2HCL                          MgCl            +        H2

The Collision Theory

A chemical reaction will only occur when particles collide, with the right amount of energy, enough energy to break bonds, this minimum amount of energy is called the activation energy. In some reactions the activation energy is low and collisions may occur at room temperature or below. Some reactions have a high activation energy therefore they have to be heated for collisions to happen. When collisions happen in different concentrations of a solution, in our experiment hydrochloric acid, the rate of reaction either increases or decreases. If there is a low concentration in a solution the rate of reaction is slower, but when there is a high concentration in a solution the reaction is much faster because the particles of a reactant are much closer together and collide more frequently, therefore with more force, to break bonds. To break bonds, you need a certain amount of energy; this is called the activation energy. When there is enough energy a faster reaction will occur. When there is a higher concentration of acid there will be more available energy that can be used to break bonds, this means that the reaction will be faster than with a lower concentration of acid. In my experiment there are two ways I can draw a graph. One is to calculate the average and plot that and the other is to find the average and find the rate of a reaction, using the formula 1/Time (S-1). I will use both of these methods to help me find out if concentration affects rate. Other things apart from concentration can effect rate, such as Temperature, when the temperature of a reaction is increased the rate of reaction also increases, but when the temperature is decreased the rate also goes down.

Safety

  • Eye protection must be worn – acid is corrosive, especially in eyes.
  • Wipe up any spills immediately – acid is corrosive.
  • Wash skin thoroughly if spilt on skin – acid burns the skin
  • Do not run in the lab – you may knock something or someone over.

At a lower concentration of acid, there are few collisions occurring.

At a higher concentration of acid, there are many collisions with greater energy.

Pilot Experiment

              I carried out a pilot to see if the method I planned to carry out would work. I have then modified it so that my final results are more accurate than these have been. I have chosen to pilot three different concentrations because I think that piloting all the solutions would be pointless. I chose to pilot the solutions I did because they would show me a rough idea of what my real result would be like.

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Pilot Apparatus

  • 2 100ml Beakers
  • 1 25cm3 measuring cylinder
  • 1 Stopwatch
  • 2m Hydrochloric acid
  • Safety Goggles
  • Distilled water

Pilot Method

  • Collect all equipment
  • Cut 5, 1cm stripes of magnesium ribbon

  • Clean them thoroughly using sand paper

  • Measure 25cm3 of 2M Hydrochloric acid in a measuring cylinder

  • Poor the acid in to a beaker

  • Put a piece of magnesium ribbon in to the acid, at the same time starting the stopwatch

  • Stop the stopwatch.

  • Write down the results in seconds.

Diagram

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