Ok this is for a lab we are doing for equilibrium and absorbance and concentration, so i don't know if anyone can answer this.
Question: Describe how you plan to determine the temperature dependence of K sub c. Use a step by step process.
2 answers
We can't help if we don't know what you did. There are a lot of experiments out there on equilibrium, absorbance, concn, etc. Without knowing the details we can't help.
As you say Kc can be determined by using absorbance when the starting material(s) and the product(s) absorb at different wavelengths. To do this at a different temperature the easiest way is to have themostatically controlled cells and stage.
To answer the question it will depend on how far back you need to start. You will need Beer-Lambert plots for the various species and, for more precise work, at the temperatures you are going to use. For many Kc expeiments which are equilibria this can be done by forcing the equilibrium to one side or the other, e.g. by adjusting the pH in some cases. So say we have two coloured species X- and HX
HX->X- + H+
so determine Kc we need the [HX],[X-][H+]. the latter is from pH measurement. But before we start we need a calibration plot of absorbance for [HX] and [X-] on their own, which we get from determining the absorbance at various concentrations at low and high pH, which will give us HX and X- on their own respecively.
To answer the question it will depend on how far back you need to start. You will need Beer-Lambert plots for the various species and, for more precise work, at the temperatures you are going to use. For many Kc expeiments which are equilibria this can be done by forcing the equilibrium to one side or the other, e.g. by adjusting the pH in some cases. So say we have two coloured species X- and HX
HX->X- + H+
so determine Kc we need the [HX],[X-][H+]. the latter is from pH measurement. But before we start we need a calibration plot of absorbance for [HX] and [X-] on their own, which we get from determining the absorbance at various concentrations at low and high pH, which will give us HX and X- on their own respecively.
3 answers