Question

What concentration of Br−

results when 777 mL
of 0.733 M KBr
is mixed with 693 mL
of 0.461 M FeBr2?

Answer 1

To find the final concentration of Br−, calculate the moles of Br− from each solution, add them together, and divide by the total volume of the mixture in liters. This method is generally used in chemistry to determine the concentration of solutions after mixing.

Step-by-step explanation:

Calculating the Final Concentration of Br− ions

To calculate the final concentration of bromide ions (Br−) when two solutions are mixed, follow these steps:

1. Calculate the moles of Br− in the KBr solution. Use the formula moles = molarity × volume (in liters).
2. Calculate the moles of Br− in the FeBr2 solution, remembering that each FeBr2 molecule will release two Br− ions.
3. Add the moles of Br− from both solutions.
4. Find the total volume of the mixed solution by adding both volumes.
5. Calculate the final concentration of Br− by dividing the total moles of Br− by the total volume of the solution in liters.

For instance, when solving similar problems such as finding the new volume after dilution, if you start with a 0.885 M solution of KBr with an initial volume of 76.5 mL and dilute it to a 0.500 M concentration, you apply the dilution formula M1V1 = M2V2. Here, V2 is the new volume, which can be calculated using the initial and final molarities (M1 and M2) and the initial volume (V1).

Applying the method to the Bromide ion concentration problem, if the initial KBr volume and molarity is 777 mL and 0.733 M, respectively, and the FeBr2 volume and molarity is 693 mL and 0.461 M, respectively, you can find the overall Br− concentration in the final mixture.

Answer 2

Formula:

C1V1 + C2V2 = C3V3

Where C1 and V1 are the concentration and volume of the first solution, C2 and V2 are the concentration and volume of the second solution, and C3 and V3 are the concentration and volume of the resulting mixture.

Substituting the given values into the formula, we get:

(0.733 M)(0.777 L) + (0.461 M)(0.693 L) = C3(0.777 L + 0.693 L)

Simplifying the equation:

0.57084 + 0.31923 = 1.47 C3

0.89007 = 1.47 C3

C3 = 0.606 M

Therefore, the concentration of Br- in the resulting mixture is 0.606 M.