Answer: I give you three ways...
1) Break the block to obtain smaller particle size.
3) Heat the solution
1) Agitate the solution.
Step-by-step explanation:
To catalyze chemical reactions can be used different technics, few of them could involve the addition of a chemical compound named CATALYST, but also can be used physics methods to help the reactants to reach the activation energy in a smaller period.
Because catalyze a reaction means to accelerate the transformation of the reactants into products, without forcibly add a CATALYST.
1) Break the block to obtain smaller particle size.
In this particular rection, you have to notice that the Zn is presented as a BLOCK, of 15 g who's going to react with the HCl solution, to this happen, first, the block has to dissolve in the solution, the reaction is going to take a longer time, because the HCl solution can't get into the molecules inside the block of Zn until the first layers had to react.
So to accelerate this step, you can break the block of Zc, making smaller pieces, who can increase the superficial area exposition to the molecules of Zn can react with the HCl. It is known that smaller particle size can increase the capacity of the molecules of interact, and this could be reflected in the rate of the reaction. To understand this better look the image attached.
1) Agitate the solution.
To increase the rate of the reaction, you can facilitate the interaction between the particles of Zn and HCl agitating the solution, When you mix or stir the solution using a stir bar or even a spoon, you add kinetic energy to the solution, this energy makes that particles move around the solution faster, and create a good environmental of reaction. The amount of collisions who get the activation energy to transform reactant into the product is bigger than if the solution stays still.
3) Heat the solution (Carefully)
The increase of temperature in the solution is reflected in the increase of heat energy, this energy can be transformed into kinetic energy by the molecules involved in the reaction. As the agitation, heat can make those molecules collide more often, and reach in a smaller period the activation energy needed to transform reactants into products.
This has to be made carefully because HCl is a strong acid who irritates the breathing vias.