How Does Hydrochloric Acid Affect The Time Of Magnesium to Dissolve?

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How Does Hydrochloric Acid Affect The Time Of Magnesium to Dissolve?


To find the relationship between the concentration of hydrochloric acid and the time taken by Magnesium to dissolve.


Rates of Reaction -

Factors that alter speed of reactions.

1. The temperature of reactants: reactions are faster when the temperature is raised, and slower if the temperature drops.

2. The concentration of dissolved reactants (that is how much of the reactant is dissolved in a particular volume of solvent): reactions are faster at higher concentrations, and slower when the concentration is lowered.

3. The size of solid particles: powdering a solid reactant (subdividing it) makes it react more quickly.

4. The amount of solid: using more of a solid reactant makes the reaction faster (providing all of it is in contact with the others) (reactant)

The Collision Theory:

A theory to explain reaction speeds.

Reactions can be speeded up or slowed down. This is by altering the conditions of the reactants for example, reactions can be speeded up by making solutions more concentrated, or by raising the temperature.

1. Matter is made of tiny particles that are constantly moving.

2. The speed of the motion of the particles increases as the temperature rises.

- Theory from 'progress with chemistry, brian Stewart'

Kinetic theory -

State Properties Kinetic Theory Ideas

Gas Gases always spread out (diffuse) and fill up a container. They have no shape or volume of their own. Gases are very 'light' compared with solids and liquids ie they have low densities. Particles are moving about very fast all the time. The particles are a long way apart, so there is a lot of empty space between them.

Liquid Liquids have a definate volume (They dont fill any container they are put into) But they have no shape of their own. Liquids are much denser than gases. Particles are stuck to their neighbours and move about slowly. There are hardly any spaces, only a few holes every now and then.

Solid Solids have a definate shape and volume. Their densities are high, compared with gases, but not much higher than liquids. The particles are stuck to their neighbours and arranged in a pattern. The particles cannot move from place to place (but they cannot shake or vibrate on the spot)

Past Experiment

The equation for this experiment, is

HCl + Mg à MgCl2 + H2

Hydrochloric acid + Magnesium à Magnesium chloride + Hydrogen

Magnesium is a highly reactive metal. Concentrated hydrochloric acid does not have oxidation ability and acts as a reducing agent.

I have already done an experiment. This was to test the strengths or molarities of an acid. From that experiment I found out, the higher the molarity, the faster the reaction takes place.


There are 4 variables which could effect the investigation.

These are,

The Temperature,

The Concentration

The Size of the Solid &

The Amount of Solid

The Independent variable which will be used in this experiment will be The Concentration. The amount of Hydrochloric acid added to the solution.

The Dependent variable will be the time taken for the Magnesium to dissolve.


I think the higher the concentration of acid, the quicker the Magnesium will dissolve. I think this because the amount of Acid, the quicker the Magnesium particles will split in the water. Thus making the time for dissolving faster. In other words, the Rate of Reaction will happen at a faster rate.

Also stated in my theory,

"Reactions are faster at higher concentrations, and slower when the concentration is lowered."

Therefore the higher the concentration, the quicker the Magnesium will dissolve. The lower the concentration, the slower the magnesium will dissolve.


I will use the following -


Cold Water,

3cm of Magnesium,

2 Molar Concentration of Acid,



Experiment 2

1. First I...
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