Question

A group of students investigated the reaction of magnesium metal with different we . First, they added a piece of magnesium to a dilute solution of hydrochloric acid (a strong acid) and noted how long it took for 100 cm of hydrogen gas to be produced Higher • Then they repeated the experiment using a concentrated solution of ethanolo ackt (a weak acid) The amount of metal and the volume of acid was the same in both reactions. The students found that the reactions took the same amount of time to produce 100 cm³ of gas. Explain how the reaction times could be the same for the different acids​

Answer 1

The reaction rate of a chemical reaction depends on several factors, including the concentration of the reactants, temperature, surface area, and the nature of the reactants themselves. In the case of the reaction of magnesium metal with hydrochloric acid and acetic acid, the nature of the acids is different - one is a strong acid and the other is a weak acid.

A strong acid is an acid that completely dissociates into its ions when it is dissolved in water, while a weak acid only partially dissociates into its ions. In the case of hydrochloric acid, it dissociates completely into its ions, H+ and Cl-, when it is dissolved in water. This means that there are a large number of H+ ions available to react with the magnesium metal, which increases the rate of the reaction. On the other hand, acetic acid only partially dissociates into its ions, CH3COO- and H+, when it is dissolved in water. This means that there are fewer H+ ions available to react with the magnesium metal, which decreases the rate of the reaction.

However, the students found that the reaction times were the same for both acids, despite the fact that one was a strong acid and the other was a weak acid. This can be explained by the fact that the concentration of the acid used in the experiment was not specified. It is possible that the students used a higher concentration of acetic acid compared to hydrochloric acid, which compensated for the weaker acidity of acetic acid. In this case, the rate of the reaction with acetic acid would be similar to that of hydrochloric acid, resulting in the same reaction time for both acids.

Another possible explanation is that the reaction with acetic acid proceeded via a different mechanism than the reaction with hydrochloric acid. For example, acetic acid can react with magnesium metal to form a complex, which can then react further to produce hydrogen gas. This mechanism would not be affected by the weak acidity of acetic acid, and therefore the reaction time would be the same as that of hydrochloric acid.

In summary, the reaction times for the reaction of magnesium metal with hydrochloric acid and acetic acid can be the same if the concentration of the acids used is not specified, or if the reaction proceeds via a different mechanism in the case of acetic acid.