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A technician was asked to find the concentration of potassium ions in a dilute solution using a flame photometer - Edexcel - GCSE Chemistry - Question 7 - 2021 - Paper 1
Question 7
A technician was asked to find the concentration of potassium ions in a dilute solution using a flame photometer. (i) The technician first produced a calibration cu... show full transcript
Worked Solution & Example Answer:A technician was asked to find the concentration of potassium ions in a dilute solution using a flame photometer - Edexcel - GCSE Chemistry - Question 7 - 2021 - Paper 1
Step 1
display reading
Answer
To accurately plot the calibration curve using the data provided in Figure 9, the following steps should be taken:
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Prepare the Axes:
- Label the x-axis as 'concentration of potassium ions in mol dm⁻³'. Suitable scale could be set to represent concentrations such as 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5.
- Label the y-axis as 'display reading'. A corresponding scale based on the provided display readings (e.g., from 0 to 900) should be utilized.
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Plot the Points:
- Using the data from the table:
- For 0.025 mol dm⁻³, plot the point at (0.025, 180)
- For 0.050 mol dm⁻³, plot the point at (0.050, 280)
- For 0.100 mol dm⁻³, plot the point at (0.100, 440)
- For 0.200 mol dm⁻³, plot the point at (0.200, 580)
- For 0.500 mol dm⁻³, plot the point at (0.500, 900)
- Ensure each point is plotted accurately and clearly on the grid.
- Using the data from the table:
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Draw the Best Fit Curve:
- Once all points are plotted, connect them using a smooth curve that best represents the data trend. Ensure that the curve does not simply connect the dots but reflects the nature of the relationship between concentration and display reading.