Step-by-step explanation:
The reaction between magnesium ribbon and dilute hydrochloric acid is a classic example of a single replacement reaction, which can be represented by the following chemical equation:
Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g)
In this reaction, magnesium (Mg) reacts with hydrochloric acid (HCl) to form magnesium chloride (MgCl2) and hydrogen gas (H2).
The rate of this reaction can be altered by changing the concentration of the hydrochloric acid. This is because the rate of a chemical reaction depends on the concentration of the reactants. Specifically, the rate of the reaction is proportional to the concentration of the reactants raised to some power, which is determined by the reaction's rate law.
In this reaction, the rate law can be expressed as:
Rate = k [Mg] [HCl]^x
Where k is the rate constant and x is the order of the reaction with respect to hydrochloric acid. The order of the reaction with respect to magnesium is one, since the concentration of magnesium does not change during the reaction.
When the concentration of hydrochloric acid is increased, the rate of the reaction increases because there are more hydrochloric acid molecules available to collide with magnesium atoms and react. This means that the value of x is greater than zero and the reaction is dependent on the concentration of hydrochloric acid.
Conversely, when the concentration of hydrochloric acid is decreased, the rate of the reaction decreases because there are fewer hydrochloric acid molecules available to react with magnesium. This means that the value of x is less than one and the reaction is not entirely dependent on the concentration of hydrochloric acid.