Mg is ahead of Al in the electrochemical series and more reactive than Al hence Al does not react with MgCl2.
A chemical reaction is said to have occurred when new substances are formed. The reaction between magnesium chloride solution and sodium carbonate solution is a double decomposition reaction since the cations exchange anion partners in the product;
We must note that a single replacement reaction depends on the relative positions of metals in the electrochemical series. Al can react with CuCl2 because Al is more reactive than copper and ahead of Cu in the electrochemical series. On the other hand, Mg is ahead of Al in the electrochemical series and more reactive than Al hence Al does not react with MgCl2.
The best answer among the choices listed is the third option. The rate over the course of a reaction <span>decreases because the concentration of reactants decreases. As the concentration of the reactants decreases, there is less particles to form the products therefore less rate.</span>
