Beer lambert equation and concentration

[Scarpetta]

Please help, A 15.23mg sample of cocaine was cemically digested to convert its nitorgen to ammonia and then diluted to 100.00cm3. A 10.00cm3 of this solution was placed in a 50.00cm3 volumetric flask and treated with 5.0cm3 of phenol solution and 2.0cm3 of sodium hypochlorite solution. The sample was diluted to 50.00cm3 and the absorbance at 625nm was measured using a 1cm cell using water as a reference .

For calibration a standard solution was prepared by weighing 0.0100g of NH4CL into 1000.00cm3 flask and making up to volume with water. A 10.00cm3 aliquote of this solution was placed in a 50.00cm3 slask, treated with phenol and hypochlorite like the cocaine solution and made up to volume with water. The absorbance of this solution at 625nm was measured using a 1cm cell and water as a reference.

absorbance readings
Reagent blank 0.140
NH4CL standard 0.308
cocaine solution 0.592

I have to calculate the % of nitrogen by mass in the cocaine!

Can anyone explain in sensible terms how to do the calulation, i only know that the beer lambert law equation is used A=ECL / A=ECL

= A=C/A=C...

 

[GCT]

As a general procedure, you'll need to obtain the molar absorptivity value from the standard. You can subsequently correlate the ammonium concentration values for the standard as well as the digested cocaine solution.

 

[Blueshift5]

The Beer-Lambert equation is a fundamental law in spectroscopy that relates the absorbance of a solution to its concentration and the path length of the light through the solution. It is expressed as A = εlc, where A is the absorbance, ε is the molar absorptivity (a constant for a particular compound), l is the path length, and c is the concentration.

In this particular case, the Beer-Lambert equation is being used to determine the concentration of cocaine in a solution. The absorbance of the cocaine solution at a particular wavelength (625nm) is measured using a spectrophotometer. This absorbance is compared to the absorbance of a standard solution of NH4Cl, which has a known concentration. By comparing the two absorbance values, the concentration of the cocaine solution can be calculated using the Beer-Lambert equation.

To calculate the % of nitrogen by mass in the cocaine, you will need to use the molar mass of cocaine (calculated from its chemical formula) and the molar mass of nitrogen. From the concentration of the cocaine solution, you can calculate the moles of cocaine present. Since the nitrogen in cocaine is converted to ammonia in the chemical digestion process, you can use the moles of cocaine to calculate the moles of ammonia produced. From there, you can use the molar mass of nitrogen to calculate the mass of nitrogen in the cocaine sample. Finally, you can calculate the % of nitrogen by mass using the mass of nitrogen and the mass of the original cocaine sample.

In summary, the Beer-Lambert equation is used to determine the concentration of a substance in a solution by comparing its absorbance to that of a standard solution. From there, additional calculations can be done to determine the % of a particular element in the original sample.