Photo AI
In this experiment you will determine the ionic equation for the reaction of acidified potassium manganate(VII) with potassium iodide - CIE - A-Level Chemistry - Question 1 - 2015 - Paper 1
Question 1
In this experiment you will determine the ionic equation for the reaction of acidified potassium manganate(VII) with potassium iodide. Excess potassium iodide is use... show full transcript
Worked Solution & Example Answer:In this experiment you will determine the ionic equation for the reaction of acidified potassium manganate(VII) with potassium iodide - CIE - A-Level Chemistry - Question 1 - 2015 - Paper 1
Step 1
Method
Answer
- Prepare a clean conical flask and pipette 25.0 cm³ of FA 1 (potassium manganate(VII)) into it.
- Measure 25 cm³ of FA 2 (sulfuric acid) using a measuring cylinder and add it to the conical flask.
- Measure 20 cm³ of FA 3 (potassium iodide) and add it to the same flask.
- Fill the burette with FA 4 (sodium thiosulfate).
- Perform a rough titration initially to gauge the endpoint by adding FA 4 until the mixture changes to a yellow/orange color, then add starch indicator and continue until it goes colorless.
- Record the initial and final burette readings to obtain the rough titre.
- Carry out multiple accurate titrations, noting all burette readings for consistency, and calculate the consistent average for volume of FA 4 used.
Step 2
From your accurate titration results, obtain a suitable value for the volume of FA 4 to be used in your calculations.
Answer
- Calculate the average volume of FA 4 used from your accurate titrations.
- Ensure the average volume is derived from readings that fall within a total spread of 0.05 cm³ of one another for precision.
- Show clearly how this average is calculated, rounding to two decimal places as necessary.
- This value is the volume of FA 4 needed for subsequent calculations.