Final answer:
To find the concentration of SCN- in the mixture, you can calculate the moles of Fe(NO3)3 and then use stoichiometry to find the moles of SCN-. Finally, dividing the moles of SCN- by the total volume of the solution gives the concentration.
Step-by-step explanation:
To find the concentration of SCN- in the mixture, we need to determine the amount of SCN- ions present in the solution. We can use the principles of stoichiometry and molarity to calculate this.
First, let's consider the balanced chemical equation for the reaction between Fe(NO3)3 and KSCN:
Fe(NO3)3 + 3KSCN → Fe(SCN)3 + 3KNO3
From the equation, we can see that one mole of Fe(NO3)3 reacts with three moles of KSCN to form one mole of Fe(SCN)3. Therefore, the molar ratio between Fe(NO3)3 and Fe(SCN)3 is 1:1.
Given the volume and concentration of Fe(NO3)3 and KSCN solutions, we can calculate the moles of Fe(SCN)3 formed and then find the concentration of SCN- in the mixture.
Let's start with the Fe(NO3)3 solution:
moles of Fe(NO3)3 = volume (L) × concentration (M)
= 5.0 mL × (0.10 M / 1000 mL/L)
= 0.0005 moles
Since the molar ratio between Fe(NO3)3 and Fe(SCN)3 is 1:1, the moles of Fe(SCN)3 formed is also 0.0005 moles.
Now, let's calculate the concentration of SCN- in the mixture:
moles of SCN- = moles of Fe(SCN)3
concentration of SCN- = moles of SCN- / volume (L)
= 0.0005 moles / (1.5 mL + 3.5 mL) × (0.0020 M / 1000 mL/L)
= 0.0005 moles / 0.005 L × 0.0020 M
= 0.20 M
Therefore, the concentration of SCN- in the mixture is 0.20 M.