The reaction between hydrogen gas H2 and iodine gas I2 to form hydrogen iodide gas 2HI can be represented by the following balanced equation:H2 g + I2 g 2HI g This reaction is an example of a homogeneous gas-phase reaction, where all reactants and products are in the gas phase. The effect of increasing pressure on the rate of this reaction can be understood using Le Chatelier's principle, which states that if a system at equilibrium is subjected to a change in pressure, temperature, or concentration of reactants or products, the system will adjust itself to counteract the change and re-establish a new equilibrium.In this case, increasing the pressure of the system will cause the reaction to shift in the direction that reduces the number of moles of gas, in order to counteract the increase in pressure. Since the number of moles of gas is the same on both sides of the equation 1 mole of H2 + 1 mole of I2 2 moles of HI , increasing the pressure will have no effect on the position of the equilibrium.However, the rate of the reaction can still be affected by the increase in pressure. In general, increasing the pressure of a gas-phase reaction will increase the collision frequency between the gas molecules, which in turn increases the rate of the reaction. Therefore, increasing the pressure of the system will increase the rate of the reaction between hydrogen gas and iodine gas to form hydrogen iodide gas, but it will not affect the position of the equilibrium.