2
$\begingroup$

While performing flame tests for calcium fluoride and strontium fluoride, I observed strontium gives a long-lasting rose-red flame color but the brick red color for calcium quickly disappears. I also found some books mention the flame color for calcium as transient red. Why does the flame color of calcium is transient?

$\endgroup$
3
$\begingroup$

A flame is a constantly upward "moving" chemical reaction. The velocity is dependent on the flow rate of the gases entering the burner. There is an extensive upward motion (on Earth). In a gravity-less flame, the flame is round, still there is an upward movement. Now another important thing to note is that the Group II flame emission is not due their atoms but their hydroxides, such as CaOH. In an ordinary Bunsen burner flame you can expect "weird" molecules, which cannot exist in an ordinary bottle. The typical flame temperature is not hot enough to cause atomic excitation and completely break calcium compounds into calcium atoms. If this were true you would see a violet flame (422 nm) after introducing calcium. We see reddish color which is always contaminated with sodium's yellow color. The flame color is then dependent on the thermal stability and volatility of the emitting compound being formed in the flame.

$\endgroup$
  • $\begingroup$ Not sure this answers the q, because no difference between Ca and Sr is given. $\endgroup$ – Oscar Lanzi Jul 17 at 15:52

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.