Calculate the concentration of bromocresol green (BG) indicator
It says that Molar absorptivity = Absorbance at a wavelength/ concentration of BG indicator
I am having trouble calculating the concentration of BG.
Other info: Stock solution of BG = 80.0 mg/L and molar mass = 698.0 g/mol
We added 10.00 ml of stock solution to a 50.0 ml volumetric flask and diluted it to the line with 0.4M HCl
You don't have enough information posted to calculate concn.
First you need to calculate molar absorptivity, which as your post says is e = A/c (that comes from A = e*c)
If you used the diluted stock solution for that, you can calculate e by substituting the absorbance of the diluted stock solution.
Then you must have some other solution for which you want to calculate c, which can be done by A = e*c.
Post your additional information here if that is needed.
To calculate the concentration of bromocresol green (BG) indicator, we can use the dilution formula:
C1V1 = C2V2
Where:
C1 = concentration of stock solution (80.0 mg/L)
V1 = volume of stock solution used (10.00 mL)
C2 = concentration of diluted solution
V2 = total volume of diluted solution (50.0 mL)
First, convert the concentration of the stock solution to mol/L:
C1 = 80.0 mg/L = 80.0 g/1000 mL = 0.080 g/mL
Molar mass of BG = 698.0 g/mol
Now, calculate the moles of BG in the volume used:
moles of BG = (0.080 g/mL) x (10.00 mL) / (698.0 g/mol) = 0.0011479 mol
Next, calculate the concentration of the diluted solution:
C2 = (0.0011479 mol) / (50.0 mL) = 0.02296 mol/L
Therefore, the concentration of the bromocresol green (BG) indicator is approximately 0.02296 mol/L.
To calculate the concentration of bromocresol green (BG) indicator, you can use the formula:
Concentration (in mol/L) = Absorbance / Molar absorptivity
First, you need to measure the absorbance of the solution containing BG using a spectrophotometer at the appropriate wavelength. Let's say the absorbance value is A.
Next, you need to obtain the molar absorptivity (also known as molar extinction coefficient) of bromocresol green at the same wavelength. This value can be found in reference books or databases. Let's say the molar absorptivity is ε.
Now, you can plug in the values into the formula:
Concentration (in mol/L) = A / ε
However, before you can use this formula, you need to convert the concentration of the stock solution of BG from mg/L to mol/L. To do this, you can use the molar mass of BG:
Concentration (in mol/L) = (concentration of stock solution in mg/L) / (molar mass of BG in g/mol)
= 80.0 mg/L / 698.0 g/mol
So, the concentration of the stock solution is 0.114 mol/L.
Next, you diluted 10.00 ml of the stock solution in a 50.0 ml volumetric flask filled with 0.4M HCl. This means you added 10.00 ml of the stock solution to the flask and then filled it up to the mark with 0.4M HCl. This resulted in a final volume of 50.0 ml.
Using the dilution formula (C1V1 = C2V2), you can calculate the concentration of the diluted solution:
C1 = concentration of stock solution = 0.114 mol/L
V1 = volume of stock solution added = 10.00 ml = 0.010 L
V2 = final volume of diluted solution = 50.0 ml = 0.050 L
C2 = concentration of diluted solution (unknown)
C1V1 = C2V2
0.114 mol/L * 0.010 L = C2 * 0.050 L
0.00114 mol = C2 * 0.050 L
Solving for C2:
C2 = 0.00114 mol / 0.050 L
C2 = 0.0228 mol/L
So, the concentration of the diluted solution is 0.0228 mol/L.
Finally, you can calculate the concentration of the BG indicator by multiplying the concentration of the diluted solution by the dilution factor:
Concentration of BG indicator = concentration of diluted solution * dilution factor
= 0.0228 mol/L * (50.0 ml / 10.00 ml)
= 0.0228 mol/L * 5.00
= 0.114 mol/L
Therefore, the concentration of the bromocresol green (BG) indicator in the solution is 0.114 mol/L.