Increasing pressure affects the rate of the reaction between hydrogen gas H2 and iodine gas I2 to form hydrogen iodide gas 2HI by increasing the frequency of collisions between the reactant molecules. This relationship can be explained by applying the collision theory.The collision theory states that for a reaction to occur, the reactant particles must collide with each other with sufficient energy and proper orientation. When the pressure is increased, the concentration of the reactant molecules in a given volume also increases. This results in a higher probability of collisions between the reactant molecules, leading to an increased reaction rate.In the case of the reaction between hydrogen gas and iodine gas to form hydrogen iodide gas, the balanced equation is:H2 g + I2 g 2HI g As the pressure increases, the concentration of H2 and I2 molecules in the reaction vessel increases, leading to more frequent collisions between these molecules. This, in turn, increases the rate at which hydrogen iodide gas is formed.However, it is important to note that this reaction is reversible, and the increased pressure will also affect the rate of the reverse reaction the decomposition of HI into H2 and I2 . According to Le Chatelier's principle, if the pressure is increased, the system will try to counteract the change by shifting the position of the equilibrium to the side with fewer moles of gas. In this case, since there are fewer moles of gas on the left side of the equation H2 and I2 , the equilibrium will shift to favor the formation of hydrogen and iodine gas. This means that while the rate of the forward reaction may increase due to increased pressure, the overall yield of hydrogen iodide gas may not necessarily increase.In summary, increasing pressure can increase the rate of the reaction between hydrogen gas and iodine gas to form hydrogen iodide gas by increasing the frequency of collisions between reactant molecules, as explained by the collision theory. However, the effect on the overall yield of hydrogen iodide gas may be influenced by the position of the equilibrium due to Le Chatelier's principle.