See how different concentrations of Hydrochloric acid change the rate of reaction with a strip of magnesium and the rate at which hydrogen gas is produced when it has reacted.

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Shariq Janjua 11U

Science Coursework

Introduction

The aim of the investigation is to see how different concentrations of Hydrochloric acid change the rate of reaction with a strip of magnesium and the rate at which hydrogen gas is produced when it has reacted.

In the reaction between hydrochloric acid and magnesium ribbon, the hydrochloric acid will dissolve the magnesium and produce hydrogen gas.

All chemical reactions involve reactants which when added together may cause a chemical reaction which will produce products.

In my case the reactants are hydrochloric acid and magnesium ribbon. The chemical reaction takes place when the magnesium ribbon is dropped into the hydrochloric acid. The products that are formed during this reaction are hydrogen gas and magnesium chloride. The formula equation for this experiment is:

Magnesium + Hydrochloric acid                    Magnesium Chloride + Hydrogen

     ( s )                    ( aq )                                              ( aq )                    ( g )

Mg + 2HCl                MgCl2 + H2

The reaction above tells us that every magnesium atom reacts with 2 molecules of hydrochloric acid and this reaction then forms 1 atom of magnesium chloride and 1 molecule of hydrogen. This means that the reaction requires at least 1 magnesium atom and 2 molecules of hydrochloric acid for the reaction to take place.

Here is the equipment which I am planning to use in my experiment:

  • Test Tubes - This is where the chemical reactions will take place in order to find how long magnesium takes to react with different concentrations of Hydrochloric acid.
  • Test Tube Rack – This is where the test tubes are held during the course of the experiment.
  • Clamp – It is used to hold the as syringe horizontally so the results are accurate.
  • Measuring Cylinder- The cylinder will be used to accurately measure the concentration of the Hydrochloric Acid.
  • Scissors – They will be used to cut the magnesium strips into equal pieces.
  • Stopwatch – It will be used to measure time to the nearest second.
  • Delivery Tube – This tube is where the hydrogen gas travels through in order to arrive at the syringe.
  • Gas Syringe – This is where the volume of gas is measured
  • Conical Flask – This is where the chemical reactions will take place in order to find how much hydrogen gas is produced during a certain period of time.

Magnesium will react with hydrochloric acid, because it is higher in the reactivity series than hydrogen. When the two chemicals react a displacement reaction will take place and the magnesium will displace the hydrogen in the hydrochloric acid forming magnesium chloride and hydrogen gas.

Reactivity Series

K (potassium)

Na (sodium))

Li (lithium) all too dangerous to react with a strong acid

Ba (barium)

Ca (Calcium)

..

Mg (magnesium) -

Al (aluminium) manageable metals

Zn (zinc) these metals will react with hydrochloric acid as they

Fe (iron) they are higher in the reactivity series than hydrogen

Sn (tin) and so a displacement reaction will take place.

Pb (lead) ¯

..H (hydrogen)

..Cu (copper)

Hg (mercury) none of these metals will react with hydrochloric

Ag (silver) acid as they are all lower in the reactivity series than

Al (gold) hydrogen, therefore a displacement reaction will not occur.

Prediction

I predict that the higher the concentration of the acid then the higher the rate of the reaction. The collision theory which states that all substances are made up of particles. The particles might be atoms, molecules or ions. Before we can get a chemical reaction two particles must collide effectively. This is when a collision results in the formation of product molecules. The reaction rate is a measure of how frequently effective collisions occur. The more collisions between particles in a given time, the faster the reaction. This explains why an increase in the concentration of reactants will tend to lead to an increase in the rate of reaction.

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If I double the concentration of the acid from 1mole to 2moles of hydrochloric acid then I will expect to see the rate of the reaction double. This is because there are twice as many acid particles in 2moles of hydrochloric acid than in 1mole, so there will be twice the amount of collisions per second and because there are twice the amount of collisions per second then there will be twice as many successful collisions per second, increasing the speed of reaction.    

As we increase the concentration, the rate of reaction increases. There are more particles in ...

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