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5. (a) (i) Describe how you would carry out a flame test on a sample of potassium chloride - Leaving Cert Chemistry - Question 5. - 2006
Question 5.
5. (a) (i) Describe how you would carry out a flame test on a sample of potassium chloride. (ii) Why do different elements have unique atomic spectra? (iii) What i... show full transcript
Worked Solution & Example Answer:5. (a) (i) Describe how you would carry out a flame test on a sample of potassium chloride - Leaving Cert Chemistry - Question 5. - 2006
Step 1
Describe how you would carry out a flame test on a sample of potassium chloride.
Answer
To perform a flame test for potassium chloride, follow these steps:
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Preparation: Gather necessary materials including a clean platinum wire or nickel probe, concentrated hydrochloric acid, a Bunsen burner, and a sample of potassium chloride.
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Cleaning the Probe: Dip the platinum wire into the hydrochloric acid, and then place it in the flame to burn off any contaminants, ensuring it remains clean before inserting it into the sample.
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Sampling: Insert the clean wire into the potassium chloride sample to pick up a small amount.
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Conducting the Flame Test: Hold the loaded probe in the flame of the Bunsen burner and observe the color produced. Potassium typically produces a lilac or purple flame.
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Observation and Conclusion: Take notes of the flame color and intensity, which corresponds to the presence of potassium ions in the compound.
Step 2
Why do different elements have unique atomic spectra?
Answer
Different elements exhibit unique atomic spectra due to the following reasons:
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Electron Configuration: Each element has a distinct arrangement of electrons in various energy levels. This variation in the energy distribution leads to unique electron transitions, which correspond to specific wavelengths of light.
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Energy Level Differences: When electrons transition between these levels, they absorb or emit photons at characteristic energies, resulting in distinct spectral lines associated with each element.
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Nuclear Charge and Electron Interactions: The different nuclear charges and varying numbers of electrons contribute to different electron-electron repulsions and electrostatic attractions which influence the energy levels and spectral lines produced.
Step 3
What instrumental techniques is based on the fact that each element has unique atomic spectra?
Answer
The technique based on the unique atomic spectra of elements is known as atomic absorption spectroscopy (AAS). AAS measures the absorption of light by free atoms to determine the concentration of elements in a sample, utilizing the unique spectral lines each element produces.