Concentration's Effect on the Speed of Reaction Between Magnesium and Hydrochloric Acid

Concentration's Effect on the Speed of

Reaction Between Magnesium and Hydrochloric Acid

Planning 1:

The aim of this investigation is to find out the effect of acid

concentration in the reaction between dilute hydrochloric acid and

magnesium ribbon. The rate of a chemical reaction is a measure of how

fast the reaction takes place. A high concentration of hydrochloric

acid could mean a fast reaction whereas as a low concentration could

mean a slow long reaction. I will be testing different concentrations

of acid reacting with magnesium in two separate experiments, which

will hopefully prove this initial prediction.

[IMAGE][IMAGE] During my science lesson I have learnt the following

information that has enabled me to plan my investigation. Using my

science book as evidence, I feel that as I continue to add water to

the hydrochloric acid, its concentration decreases. Therefore the less

acid molecules there are the smaller the chance of them colliding with

the solid magnesium ribbon. This means decreasing the concentration of

hydrochloric acid slows down the rate of the reaction between the

magnesium ribbon and hydrochloric acid.

The diagram shows how fast acid molecules are colliding in a

concentration of 50cm3 hydrochloric acid.

There are less collisions with the magnesium ribbon (mg) in a

concentration of 40cm3 acid and 10cm3 water than a

concentration of 50cm3 acid and 0cm3 water. This is because

the 10cm3 of water has replaced 10cm3 of acid molecules, so

now there are less acid molecules to collide with the Mg

ribbon.

= Magnesium molecule

= Hydrochloric acid molecule

= Movement

Planning 2:

[IMAGE]Magnesium + Hydrochloric Acid Magnesium Chloride + Hydrogen

[IMAGE]Mg + 2HCL (aq) MgCl2 + H2 (g)

The information in the paragraph that follows was researched from a

secondary source, which enabled me to further plan my investigation.

According to the collision theory, the more concentrated the reaction

the greater the number of collisions between reactant molecules. This

explains why the rate of reaction is highest when the reactants are