college chemistry-absorbance of an equilibrium mixture
Problem: A student mixed 4.00mL of 1.02x10^(-1) M Fe(NO3)3 with 100.00mL of 1.98*10^(-4) M KSCN, using 5.0*10^(-1) M HNO3 as the solvent for both solutions, and found the absorbance of the resulting equilibrium mixture to be .253. Given these data, calculate the following:
1. [Fe*]
2. [SCN*]
3.[Fe*] + [SCN*]
4.[Fe*][SCN*]
5.A([Fe*] + [SCN*])
6.A / ([Fe*][SCN*])
7. (A([Fe*] + [SCN*]))/([Fe*][SCN*])
I would like the process explained to me, not the answers! (please)
thanks.
ClO32- + cl- = cl2 + ClO2 balanced net ionic equation
To solve this problem, we will use Beer's Law, which relates the absorbance of a solution to the concentration of the absorbing solute. The equation for Beer's Law is:
A = ɛbc
where A is the absorbance, ɛ is the molar absorptivity (a constant for a given compound), b is the path length (usually the thickness of the cuvette), and c is the concentration of the absorbing solute.
In this case, we are given the absorbance of the equilibrium mixture, which is A = 0.253. We need to calculate the concentrations of Fe\(^*\) and SCN\(^*\) ions in the solution.
1. [Fe\(^*\)]:
Using Beer's Law, we have A = ɛbc.
Rearranging the equation, we can solve for c:
c = A / ( ɛb)
Here, we need the molar absorptivity (ɛ) and the path length (b) for Fe\(^*\) ions. The molar absorptivity is usually given for a specific wavelength and substance. Assuming it is given in the problem or known, we can substitute the values into the equation to calculate [Fe\(^*\)].
2. [SCN\(^*\)]:
We can repeat the same process as above to calculate the concentration of SCN\(^*\) in the solution.
3. [Fe\(^*\)] + [SCN\(^*\)]:
We can simply add the concentration of Fe\(^*\) and SCN\(^*\) ions obtained in steps 1 and 2, respectively, to find their sum.
4. [Fe\(^*\)][SCN\(^*\)]:
We multiply the concentrations of Fe\(^*\) and SCN\(^*\) ions obtained in steps 1 and 2, respectively, to find their product.
5. A([Fe\(^*\)] + [SCN\(^*\)]):
We multiply the absorbance obtained in the problem statement (A = 0.253) by the sum of the concentrations of Fe\(^*\) and SCN\(^*\) ions obtained in step 3.
6. A / ([Fe\(^*\)][SCN\(^*\)]):
We divide the absorbance obtained in the problem statement (A = 0.253) by the product of the concentrations of Fe\(^*\) and SCN\(^*\) ions obtained in step 4.
7. (A([Fe\(^*\)] + [SCN\(^*\)])) / ([Fe\(^*\)][SCN\(^*\)]):
We divide the product calculated in step 5 by the product calculated in step 6 to find the final answer.
By following these steps and performing the necessary calculations using the given values, you will be able to find the answers to all the questions.