In the laboratory a student combines 41.7 mL of a 0.386 M iron(III) fluoride solution with 21.3 mL of a 0.616 M iron(III) bromide solution.
What is the final concentration of iron(III) cation ?
What is (41.7*.386+21.3*.616)/(41.7+21.3)
Now why does that work? Remember in algebra the candy mix problems?
To find the final concentration of the iron(III) cation, we need to calculate the number of moles of iron(III) cation resulting from the reaction between the iron(III) fluoride and iron(III) bromide solutions, and then divide it by the total final volume of the solution.
Here's how to get the answer step-by-step:
Step 1: Calculate the moles of iron(III) fluoride solution used.
Number of moles of iron(III) fluoride (FeF3) = Volume (in liters) × Concentration (in moles/L)
First, convert the volume of iron(III) fluoride solution from milliliters (mL) to liters (L):
Volume of iron(III) fluoride solution = 41.7 mL ÷ 1000 mL/L = 0.0417 L
Now calculate the moles of iron(III) fluoride:
Moles of iron(III) fluoride = 0.0417 L × 0.386 moles/L = 0.016075 moles
Step 2: Calculate the moles of iron(III) bromide solution used.
Number of moles of iron(III) bromide (FeBr3) = Volume (in liters) × Concentration (in moles/L)
First, convert the volume of iron(III) bromide solution from milliliters (mL) to liters (L):
Volume of iron(III) bromide solution = 21.3 mL ÷ 1000 mL/L = 0.0213 L
Now calculate the moles of iron(III) bromide:
Moles of iron(III) bromide = 0.0213 L × 0.616 moles/L = 0.0131028 moles
Step 3: Add the moles of iron(III) cation from both solutions.
Total moles of iron(III) cation = Moles of iron(III) fluoride + Moles of iron(III) bromide
Total moles of iron(III) cation = 0.016075 moles + 0.0131028 moles
Total moles of iron(III) cation = 0.0291778 moles
Step 4: Calculate the final concentration of iron(III) cation.
Final volume of the solution = Volume of iron(III) fluoride solution + Volume of iron(III) bromide solution
Final volume of the solution = 0.0417 L + 0.0213 L
Final volume of the solution = 0.063 L
Final concentration of iron(III) cation = Total moles of iron(III) cation / Final volume of the solution
Final concentration of iron(III) cation = 0.0291778 moles / 0.063 L
Final concentration of iron(III) cation = 0.463 M
Therefore, the final concentration of the iron(III) cation is 0.463 M.