What Effect Will the Concentration of Hydrochloric Acid Have on the Rate of Reaction Between Hydrochloric Acid and Magnesium?

1541 Words May 2nd, 2011 7 Pages

In this chemical reaction, the magnesium will dissolve in the hydrochloric acid to produce hydrogen gas. This is because magnesium is higher than hydrogen in the reactivity series. Therefore, when the two reactants are combined, a displacement reaction occus and the magnesium displaces the hydrogen, forming magnesium chloride and hydrogen gas.

Mg (s) + 2HCl (aq) -> MgCl 2 (aq) + H 2 (g)

Magnesium + Hydrochloric acid -> Magnesium Chloride + Hydrogen


The aim of this investigation is to observe the effect that the concentration of hydrochloric acid (independent variable) has on the rate of reaction (dependent variable) between the magnesium ribbon and the hydrochloric acid.
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If there is more surface area exposed to the hydrochloric acid, the particles of acid will have a greater area of magnesium to react with and form successful collisions, thus increasing the rate of reaction.

- Volume of Hydrochloric Acid Used:

An overall volume of 50ml of hydrochloric acid and water should be used for every trial.
If a lesser volume is used, this will decrease the rate of reaction as there will be less particles in the HCl to collide with the Mg particles, which will lessen the chance for creating a successful collision, and thus lower the rate of the chemical reactions. - Timing of the experiment:

Bung with delivery tube should be placed on the conical flask as soon as possible after the magnesium ribbon is dropped. This will ensure that as much of the hydrogen gas gets measured in the measuring cylinder above the trough, in order to obtain accurate measurements when calculating the rate of reactions. Stopwatch will begin as soon as the magnesium is dropped into the hydrochloric acid, so that the timing of the reaction is measured accurately.

- Cleaning of the magnesium: The ribbon of magnesium will be cleaned with sandpaper to remove the coating on the magnesium metal caused by reactions with atmospheric gases. This needs to be done so that the measuring cylinder measures the gas produced from the reaction