I would assume that the light intensity will be greater if the concentrations of reactants being reacted are greater. Calibration is setting the equipments to their standards. Do you mean that I can come up with a relation between the concentrations and the light intensity of the reaction and then find the constant by actually conducting the experiment?Borek said:Can you think about any dependence between the light intensity and concentration? Do you know what calibration is?
ChanYoung Park said:I was wondering how I could measure the rate constant k for chemiluminescence reaction of luminol (when oxidised by H2O2. I was told that I can use a lux meter that measures the intensity of light emitted, but I'm not so sure how this can be done since the equation calculating the rate constant uses the concentrations of reactants and products. What will be a practical method to measure the rate of luminol reaction?
ChanYoung Park said:Do you mean that I can come up with a relation between the concentrations and the light intensity
ChanYoung Park said:a relation between the concentrations and the light intensity of the reaction
I think I phrased it wrong there. What I meant was that I would want to find the rate of reaction.DrDu said:I wonder whether this reaction can be described in terms of a single reaction constant anyhow.
So... to rephrase what you said - please check if I'm right on the track - the light intensity of the light emitted at time t will be directly proportional to the number of reactant molecules reacting at time t, and based on this logic, I'll be able to know how the rate of reaction changes as time passes (using light intensity-time graph). Though how can I figure out the exact value of rate of reaction? I'm guessing that I would need to calculate E=hv per exicted mol and divide the energy emitted by the E value to get the mol of reactants. Will this work?Borek said:That for sure.
Beware: "light intensity of the reaction" sound strange. "Reaction" itself doesn't produce light. Reacting molecules do, so the amount of light produced will be proportional to the number of reacting molecules (and in turn will depend on the concentration, or more precisely concentration change).
I fear it is difficult to obtain absolute concentrations from the light measurements. The point is that it depends strongly on the geometry of your setup (percentage of the light reaching the detector), the sensitivity of the detector, internal absorption of radiation, photon efficiency of the reaction ...ChanYoung Park said:So... to rephrase what you said - please check if I'm right on the track - the light intensity of the light emitted at time t will be directly proportional to the number of reactant molecules reacting at time t, and based on this logic, I'll be able to know how the rate of reaction changes as time passes (using light intensity-time graph). Though how can I figure out the exact value of rate of reaction? I'm guessing that I would need to calculate E=hv per exicted mol and divide the energy emitted by the E value to get the mol of reactants. Will this work?
Hi, may I please ask what method you decided to use at the end to determine this? I'm doing a similar experiment, but I am currently also confused about how to measure the rate.ChanYoung Park said:I was wondering how I could measure the rate constant k for chemiluminescence reaction of luminol (when oxidised by H2O2. I was told that I can use a lux meter that measures the intensity of light emitted, but I'm not so sure how this can be done since the equation calculating the rate constant uses the concentrations of reactants and products. What will be a practical method to measure the rate of luminol reaction?
Luminol is a chemical compound that is commonly used in scientific experiments as a reagent to detect the presence of blood or other substances. It is also used in chemistry to measure the rate of certain reactions, as it produces a blue glow when it reacts with an oxidizing agent.
The rate of a luminol reaction can be affected by several factors, including the concentration of the luminol solution, the presence of catalysts or inhibitors, temperature, and pH level. These factors can either increase or decrease the rate of the reaction.
The rate of a luminol reaction can be measured using a spectrophotometer, which measures the absorbance of light by the luminol solution at different time intervals. The higher the absorbance, the faster the reaction is occurring. The data collected can then be used to calculate the reaction rate using the Beer-Lambert Law.
Accurately measuring the rate of a luminol reaction is important for several reasons. It can provide insight into the kinetics of the reaction, which can help in understanding the underlying mechanisms and factors that affect it. It can also be used to compare the effectiveness of different catalysts or inhibitors in the reaction.
Yes, there are some safety precautions that should be taken when working with luminol. It is recommended to wear gloves and protective eyewear, as the compound can be harmful if it comes into contact with skin or eyes. It is also important to properly dispose of any leftover luminol solution and clean up any spills to avoid contamination.