Record measured absorbance for each tube in following table. Complete the table by calculating the [ Fe(SCN2+)]eq and [Fe3+]initial and [HSCN]initial
Data:
Volume of 2.00 x 10-3 M Fe(NO3)3 solution, mL 1)5.00, 2) 5.00, 3) 5.00 4) 5.00 5) 5.00
Volume of 2.00 x 10-3 M HSCN solution, mL 1)1.00 2) 2.00 3) 3.00 4) 4.00 5) 5.00
Volume of 0.500 M HNO3 solution, mL 1) 4.00 2) 3.00 3) 2.00 4) 1.00 5) 0.00
Abs. 1) 0.113 2) 0.218 3) 0.324 4) 0.459 5) 0.550
To calculate the [Fe(SCN)2+]eq, [Fe3+]initial, and [HSCN]initial, we need to first understand the reaction that is taking place.
The reaction is as follows:
Fe3+ + SCN- ⇌ Fe(SCN)2+
In this reaction, Fe(SCN)2+ is the product formed from the reaction between Fe3+ and SCN-. The absorbance of the solution is directly proportional to the concentration of Fe(SCN)2+.
1. To calculate the [Fe(SCN)2+]eq for each tube, we can use the Beer-Lambert Law, which states that the absorbance is equal to the molar absorptivity (ε) times the concentration (c) times the path length (b):
Abs = εcb
In this case, the path length (b) is constant, so we just need to calculate the concentration (c) for each tube.
For Tube 1:
[Fe(SCN)2+]eq = (Abs1 / ε) = (0.113 / ε)
For Tube 2:
[Fe(SCN)2+]eq = (Abs2 / ε) = (0.218 / ε)
For Tube 3:
[Fe(SCN)2+]eq = (Abs3 / ε) = (0.324 / ε)
For Tube 4:
[Fe(SCN)2+]eq = (Abs4 / ε) = (0.459 / ε)
For Tube 5:
[Fe(SCN)2+]eq = (Abs5 / ε) = (0.550 / ε)
2. To calculate [Fe3+]initial, we need to consider the stoichiometry of the reaction. The molar ratio between Fe3+ and Fe(SCN)2+ is 1:1.
So, [Fe3+]initial = [Fe(SCN)2+]eq
3. To calculate [HSCN]initial, we need to know the volume and concentration of the HSCN solution added.
For Tube 1:
[HSCN]initial = (Volume of HSCN solution in tube 1) x (Concentration of HSCN solution) = (1.00 mL) x (2.00 x 10-3 M)
For Tube 2:
[HSCN]initial = (Volume of HSCN solution in tube 2) x (Concentration of HSCN solution) = (2.00 mL) x (2.00 x 10-3 M)
For Tube 3:
[HSCN]initial = (Volume of HSCN solution in tube 3) x (Concentration of HSCN solution) = (3.00 mL) x (2.00 x 10-3 M)
For Tube 4:
[HSCN]initial = (Volume of HSCN solution in tube 4) x (Concentration of HSCN solution) = (4.00 mL) x (2.00 x 10-3 M)
For Tube 5:
[HSCN]initial = (Volume of HSCN solution in tube 5) x (Concentration of HSCN solution) = (5.00 mL) x (2.00 x 10-3 M)
So, now we have calculated the [Fe(SCN)2+]eq, [Fe3+]initial, and [HSCN]initial values for each tube by using the provided data.