This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
ScanSolve AI Answer
7 stepsAnswer
Concentration × Volume (in dm³)
Hope, let's knock this out.
Here are the full steps involved in a redox titration, using a Paper 3 question as an example:
General Steps for Redox Titration:
Preparation of Solutions:
Rinsing Apparatus:
Setting Up Titration:
Performing Rough Titration:
Performing Accurate Titrations:
Recording Results:
Calculations:
Example Paper 3 Question and Solution:
Question: A student is tasked with determining the concentration of iron(II) ions in a solution. They are provided with a 0.0200 mol/L potassium permanganate (KMnO₄) solution and an unknown solution containing Fe²⁺ ions. a) Describe the steps involved in performing the titration to determine the concentration of Fe²⁺ ions. b) If 25.00 cm³ of the Fe²⁺ solution required an average of 22.50 cm³ of the 0.0200 mol/L KMnO₄ solution for complete reaction, calculate the concentration of Fe²⁺ ions in the unknown solution. The balanced ionic equation for the reaction is: MnO₄⁻(aq) + 5Fe²⁺(aq) + 8H⁺(aq) → Mn²⁺(aq) + 5Fe³⁺(aq) + 4H₂O(l)
Solution:
a) Steps for performing the titration:
Step 1: Rinse and Prepare Apparatus Rinse the burette with 0.0200 mol/L KMnO₄ solution. Rinse the pipette with the unknown Fe²⁺ solution. Rinse the conical flask with distilled water.
Step 2: Set Up Titration Fill the burette with the 0.0200 mol/L KMnO₄ solution, ensuring the meniscus is at the zero mark. Pipette 25.00 cm³ of the unknown Fe²⁺ solution into a conical flask. Add about 10 cm³ of dilute sulfuric acid to provide the necessary H⁺ ions for the reaction. No external indicator is needed as KMnO₄ is self-indicating.
Step 3: Perform Rough Titration Add the KMnO₄ solution from the burette to the conical flask, swirling constantly, until the first permanent faint pink color appears, indicating the endpoint. Record this approximate volume.
Step 4: Perform Accurate Titrations Refill the burette. Repeat the titration with fresh 25.00 cm³ aliquots of Fe²⁺ solution. Add KMnO₄ rapidly until within 1-2 cm³ of the rough titre, then add drop by drop, swirling after each drop, until the first permanent faint pink color persists for at least 30 seconds. Record the initial and final burette readings for each accurate titration.
Step 5: Record and Average Results Record all accurate titre volumes in a table. Calculate the average titre from concordant results (e.g., within 0.10 cm³ of each other).
b) Calculation of Fe²⁺ concentration:
Step 1: Calculate moles of KMnO₄ used Moles = Concentration × Volume (in dm³) Moles of KMnO₄ = 0.0200 mol/L × (22.50 / 1000) L Moles of KMnO₄ = 0.000450 mol
Step 2: Determine moles of Fe²⁺ reacted using stoichiometry From the balanced equation, the mole ratio of MnO₄⁻ : Fe²⁺ is 1 : 5. Moles of Fe²⁺ = Moles of KMnO₄ × 5 Moles of Fe²⁺ = 0.000450 mol × 5 Moles of Fe²⁺ = 0.00225 mol
Step 3: Calculate the concentration of Fe²⁺ Concentration = Moles / Volume (in dm³) Concentration of Fe²⁺ = 0.00225 mol / (25.00 / 1000) L Concentration of Fe²⁺ = 0.00225 mol / 0.02500 L Concentration of Fe²⁺ = 0.0900 mol/L
Send me the next one 📸
Get instant step-by-step solutions to any question. Free to start.
Ask Your QuestionStill have questions?
Hope, let's knock this out. Here are the full steps involved in a redox titration, using a Paper 3 question as an example: General Steps for Redox Titration: 1.
This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.