Question

Briefly explain why the blue glass blocks the yellow light of the sodium ion flame but still allows the violet light of the potassium ion flame to pass through

Answer 1

Blue glass is colored blue because it will absorb the yellow and red light spectrum. The result should be only blue light reflected or pass through the glass. Cobalt glass is used to filter out the light made by sodium because sodium can produce a high-intensity light that could mask other metal.