When the hydrogen chloride concentration doubles, the number of collisions between the reactants of the forward reaction increases, which causes the rate increases.
Here is the detailed reasoning behind this:
1. The reaction given is:
[tex]\[ CaCO _3 + 2 HCl \rightarrow CaCl _2 + CO _2 + H _2 O \][/tex]
2. According to the principles of chemical kinetics, specifically the collision theory, the rate of reaction depends on the frequency of collisions between the reactant molecules.
3. By increasing the concentration of one of the reactants, in this case, hydrogen chloride (HCl), there are more HCl molecules available in the mixture.
4. With more HCl molecules present, the probability of collisions between calcium carbonate (CaCO _3) and HCl molecules increases.
5. As a result, when the concentration of hydrogen chloride doubles, the number of effective collisions between the reactants increases.
6. An increase in the frequency of these effective collisions leads to a higher reaction rate.
Thus, the correct choices are:
- First drop-down menu: increases
- Second drop-down menu: increases
