How does varying the concentration in a reaction affect the rate of reaction?

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How does varying the concentration in a reaction affect the rate of reaction?

Introduction

To investigate how concentration affects the rate of reaction, I shall be reacting magnesium with hydrochloric acid. I will keep the length and weight of the magnesium the same and will change the concentrations of the hydrochloric acid.

Fair testing

To make it a fair test, I will keep the length and weight of the magnesium the same at all times. I will change the concentrations of hydrochloric acid and I will measure the volume of hydrogen produced. At all times during the experiment, I will stop the stopwatch when the volume of hydrogen produced reaches 20cm3.

Preliminary Experiments

Experiment 1

An experiment was set up in which a 3cm strip of magnesium was reacted with 1M of hydrochloric acid. The aim was to set up the actual experiment and to time how long it would take for certain volumes of hydrogen to be produced from the reaction. This would mean I could make a decision on how I would conduct my own experiment. Firstly, the magnesium was placed inside the hydrochloric acid. The bung was closed and after every 5 cm3 of hydrogen produced, the time was recorded. These were the results obtained from the experiment:

As a result of the experiment, I have decided to stop timing my actual experiment when the amount of hydrogen produced reaches 20 cm3. This is because I think it will give me enough time to stop the stopwatch quickly enough on the higher concentrations and will not take too long to produce the hydrogen for lower concentrations.

Experiment 2

The aim of this experiment was to find out how the temperature of the reaction will change during my experiment. I put 3cm of magnesium into a conical flask which had 100cm3 of 2M of HCl. The temperature change from the start of the experiment to the end of the experiment was 1oC. This experiment will change my prediction because a change in temperature can affect the rate of reaction.

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Method

  1. I will set up the apparatus as shown below.
  2. The volume of acid will be 100cm3 and the length of the magnesium will be 3cm.
  3. I will be using different concentrations of hydrochloric acid. They will be 0.5M, 1.0M, 1.5M, 2.0M, 3.0M and 4.0M. I will not use a concentration lower than 0.5M because I think it will take too long to produce 20cm3 of hydrogen. I will not use more than 4.0M because I think the reaction will be too quick for me to stop the stopwatch in time.
  4. I will put the ...

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This is a well structured laboratory report. The data collected is of a reasonable quality. Specific strengths and improvements have been suggested throughout.