The effect of changing light intensity on the rate of a specific chemical reaction depends on whether the reaction is photochemical or not. In photochemical reactions, light acts as a catalyst, and the reaction rate is directly influenced by the light intensity. In general, an increase in light intensity will increase the rate of a photochemical reaction, while a decrease in light intensity will slow down the reaction rate. This is because light provides the energy required for the reactants to overcome the activation energy barrier, leading to the formation of products.To quantitatively measure the effect of light intensity on the rate of a specific chemical reaction using a spectrophotometer, you can follow these steps:1. Choose a suitable wavelength: Select a wavelength at which the reactant or product of interest has a strong absorbance. This will ensure that the spectrophotometer can accurately measure the concentration changes during the reaction.2. Prepare reaction mixtures: Prepare a series of reaction mixtures with varying light intensities. This can be achieved by using neutral density filters or adjusting the distance between the light source and the reaction mixture.3. Measure absorbance: At regular time intervals, measure the absorbance of each reaction mixture using the spectrophotometer. Make sure to use a blank a solution without the reactant or product of interest to zero the spectrophotometer before each measurement.4. Plot the data: For each reaction mixture, plot the absorbance values against time. The slope of the resulting curve represents the reaction rate.5. Analyze the results: Compare the reaction rates obtained at different light intensities. A higher reaction rate indicates a faster reaction, while a lower reaction rate indicates a slower reaction. This will allow you to determine the effect of light intensity on the rate of the specific chemical reaction.In conclusion, the effect of changing light intensity on the rate of a specific chemical reaction can be quantitatively measured using a spectrophotometer. This method is particularly useful for studying photochemical reactions, where light plays a crucial role in the reaction process.