Question

in this experiment, you are asked to combine 5.0 ml of 0.10 m fe(no3)3 with 1.5 ml of 0.0020 m kscn and 3.5 ml of hno3. what is the concentration of scn- in this mixture?

Answer 1

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.

Answer 2

The final concentration of SCN- in the mixture is 0.0003 M, calculated using a dilution formula considering the initial concentration and volume of KSCN and the total mixture volume.

Step-by-step explanation:

To calculate the concentration of SCN- in the experiment, we need to consider the volumes and concentrations of KSCN and the total volume of the mixture. We'll use the formula for dilution: C1V1 = C2V2, where C1 is the initial concentration, V1 is the initial volume, C2 is the final concentration, and V2 is the final volume.

The initial concentration of SCN- (C1) is 0.0020 M, and the initial volume (V1) is 1.5 mL. The final volume (V2) is the sum of all the volumes of the substances mixed: 5.0 mL of Fe(NO3)3, 1.5 mL of KSCN, and 3.5 mL of HNO3, adding up to 10.0 mL.

To find the final concentration of SCN- (C2), we rearrange the formula to C2 = (C1V1) / V2 and get C2 = (0.0020 M * 1.5 mL) / 10.0 mL = 0.0003 M. Therefore, the final concentration of SCN- in the mixture is 0.0003 M.