The flame test for sodium is based on the intense yelloworange emission at 589 nm; the test for potassium is based on its emission at 404 nm. When both elements are present, the Na⁺ emission is so strong that the K⁺ emission can't be seen, except by looking through a cobalt-glass filter. (a) What are the colors of these Na⁺ and K⁺ emissions? (b) What does the cobalt-glass filter do? (c) Why are the oxidizing agents in fireworks made of KClO₄ or KClO₃, rather than the corresponding sodium salts?

Question

Westie

Chemistry

2 September, 01:52

The flame test for sodium is based on the intense yelloworange emission at 589 nm; the test for potassium is based on its emission at 404 nm. When both elements are present, the Na⁺ emission is so strong that the K⁺ emission can't be seen, except by looking through a cobalt-glass filter. (a) What are the colors of these Na⁺ and K⁺ emissions? (b) What does the cobalt-glass filter do? (c) Why are the oxidizing agents in fireworks made of KClO₄ or KClO₃, rather than the corresponding sodium salts?

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Valery Dennis · Answer 1

a) The flame test of Na, at 589nm will show a golden yellow color when the sodium ion is emitted. These is due to the electropositive nature of the alkali metals.

While the flame test for K at 404nm will ignite a violet color when the Potassium ion is emitted. This properties are due to the high electropositive nature of the group1 elements which also indicate their strong reducing agent.

b) The cobalt glass filter act as hindrance during the flame test to seperate or filter the golden yellow color caused as a result of the presence of the sodium, as it makes the violet color to be more visible.

c) These is due to the Oxidizing ability of KClO₄ or KClO₃ compared to the salts of sodium. Also is the low solubility of the two salts and their solubility constant (Ksp) compared to sodium salts.

Explanation:

a) The flame test of Na, at 589nm will show a golden yellow color when the sodium ion is emitted. These is due to the electropositivity nature of the alkali metals.

While the flame test for K at 404nm will ignite a violet color when the Potassium ion is emitted. This properties are due to the high electropositivity nature of the group1 elements which also indicate their strong reducing agent.

b) The cobalt glass filter act as hindrance during the flame test to seperate or filter the golden yellow color caused as a result of the presence of the sodium, as it makes the violet color to be more visible.

c) These is due to the Oxidizing ability of KClO₄ or KClO₃ compared to the salts of sodium. Also is the low solubility of the two salts and their solubility constant (Ksp) compared to sodium salts.