Which ion is indicated by a blue-green flame?

Study for the IGCSE Edexcel Chemistry Test. Access flashcards and multiple choice questions with hints and explanations. Get ready for your exam!

Multiple Choice

Which ion is indicated by a blue-green flame?

Explanation:
The flame color test works because heating a metal ion excites its electrons, and when those electrons drop back to lower energy levels they emit light at specific wavelengths. Copper(II) ions emit light in the blue-green part of the spectrum, so their flame appears turquoise or blue-green. This color is distinct from the other common flame colors: sodium gives a strong bright yellow, calcium gives a brick-red/orange-red, and iron(III) tends to a yellowish-orange. So a blue-green flame is a good indicator of copper(II) ions.

The flame color test works because heating a metal ion excites its electrons, and when those electrons drop back to lower energy levels they emit light at specific wavelengths. Copper(II) ions emit light in the blue-green part of the spectrum, so their flame appears turquoise or blue-green. This color is distinct from the other common flame colors: sodium gives a strong bright yellow, calcium gives a brick-red/orange-red, and iron(III) tends to a yellowish-orange. So a blue-green flame is a good indicator of copper(II) ions.

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