can\'t figure out how to do this. I\'ve provided the data we obtained from the l
ID: 561738 • Letter: C
Question
can't figure out how to do this. I've provided the data we obtained from the lab.
EQUILIBRIUM Questions 1. How would the absorbance of the standard solution u be 1) have been affected if 0.30 M Fe(NOs)h had used in place of 0.20 M? Remember that for the standard solution we have assumed that the reaction has h driven completely to FeSCN*. If it changes, calculate the new absorbance based on your values. 2. How would the absorbance of the sta ndard solution have been affected if0.00050 M NaSCN had been used in place of 0.00040 M? If it changes, calculate the new absorbance based on your values.Explanation / Answer
1) The values provided in the question doesn’t match the ones in the data; I will use the values provided in the question.
Write down the balanced chemical equation for the reaction between Fe3+ and SCN- as below.
Fe3+ (aq) + SCN- (aq) -------> [Fe(SCN)2+]
As per the stoichiometric equation,
1 mole Fe3+ = 1 mole SCN- = 1 mole [Fe(SCN)]2+.
[Fe(SCN)2+] is the colored compound responsible for absorption of light while Fe3+ and SCN- are colorless and hence do not absorb light.
In the first part of the experiment, the concentration of Fe3+ is much higher than the concentration of SCN-. This is done to ensure that the reaction goes to completion and the system contain only [Fe(SCN)]2+. SCN- is the limiting reactant in the reaction and the yield of [Fe(SCN)]2+ is equal to the amount (in moles) of SCN- used. Since the amount (in moles) of SCN- remain unchanged, the final concentration of [Fe(SCN)2+] remains unchanged.
The absorbance of the solution depends only on the concentration of [Fe(SCN)2+] in the system. Since there is no change in the concentration of [Fe(SCN)2+], the absorbance will remain the same.
2) The values in the data do not match the values given in the question. Kindly clarify.