Answer:
[SCN-] = 0.00012 M
[Fe3+] = 0.021 M
Explanation:
Step 1: Data given
Volume of a 4.8 *10^-4 M NaSCN solution = 5.00 mL = 0.005 L
Volume of a 0.21 M Fe(NO3)3 = 2.00 mL = 0.002 L
Volume of a 0.3 M HNO3 = 13.00 mL =0.013 L
Step 2: Calculate moles NaSCN
Moles NaSCN = molarity * volume
Moles NaSCN = 4.8 *10^-4 M * 0.005 L
Moles NaSCN = 0.0000024 moles
Step 3: Calculate moles SCN-
For 1 mol NaSCN we have 1 mol SCN-
For 0.0000024 moles NaSCN e have 0.0000024 moles SCN-
Step 4: Calculate moles of Fe(NO3)3
Moles Fe(NO3)3 = 0.21 M * 0.002 L
Moles Fe(NO3)3 = 0.00042 moles
Step 5: Calculate moles Fe3+
For 1 mol Fe(NO3)3 we have 1 mol Fe3+
For 0.00042 mol Fe(NO3)3 we have 0.00042 mol Fe3+
Step 6: Calculate the analytical concentrations
Total volume = 5.00 mL + 2.00 mL + 13.00 mL = 20.00 mL = 0.02 L
[SCN-] = 0.0000024 moles / 0.02 L
[SCN-] = 0.00012 M
[Fe3+] = 0.00042 moles / 0.02 L
[Fe3+] = 0.021 M