Experiment to find out if changing the Concentration of Acid affects the rate of its reaction with Magnesium.

JOTSAROOP VIRDEE

11 YELLOW

AIM: Experiment to find out if changing the Concentration of Acid affects the rate of its reaction with Magnesium.

INTRODUCTION – The experiment I have chosen to do is to change the amount of concentration and see with each amount of concentration if it affects the rate of reaction with Magnesium. Recently in class we have been learning about Rates of Reaction and what affects it. There are four main things that affect it :- temperature, concentration, surface area and catalysts.

PREDICTION- I predict that as the concentration of the hydrochloric acid increases, the time taken for the magnesium to disappear decreases. I also predict that when the concentration of the hydrochloric acid is doubled, the rate of reaction is also doubled.

I am predicting this due to the collision theory. The collision theory describes how the rate of reaction increases (the time taken for the magnesium ribbon to disappear when it is reacted with hydrochloric acid) when the concentration of HCl increases. The theory states that if, the more concentrated the reactants, the greater the number of collisions between particles increase. This also explains why the greatest rate of reaction is usually as soon as the reactants have been mixed, i.e. they are both at their highest concentrations. AS the reaction continues, the concentration of the reacting substances decreases and so does the rate of reaction. We must consider what happens when a reaction takes place. First of all the particles of the reacting substances must collide with each other, and secondly a fixed amount of energy called activation energy (Ea) must be reached if the reaction is to take place. If particles can produce the right amount of energy (i.e. if they collide fast enough and in the right direction) a reaction will take place. The reaction is speeded up if the number of collisions is increased. If I have a 1 Molar solution, there would be more acid particles to attack the magnesium ribbon resulting in it much faster, but if I have a 0.6 Molar solution, there would be less acid particles to attack the magnesium ribbon resulting in it being much slower. I am also predicting the best fit line of the graph for a 1 Molar solution is going to be steeper than a 0.6M solution, this is because the reactivity takes less time means the line is going to be much closer to the ‘y’ axis. There is one other thing that I am predicting; each experiment is going to give of the same amount of gas, e.g. 18cm3. I am predicting this because a 2cm long piece of magnesium ribbon should give out the same amount of gas because it is not being changed in each experiment. Here is a predicted graph sketch for my results. The different colours represent different concentrations.

FAIR TEST- In this experiment we will only change one factor, the amount of concentration, the factors that I am going to keep the same are as follows:

We must keep the surroundings the same. If we change the temperature, the particles would move faster, therefore colliding into other particles more resulting in an increase of heat temperature within the wire affecting the time.

I must make sure that the volume of the liquid in the Conical Flask must be exactly 50ml otherwise there might be too little or too much acid. This is a huge factor ...