Chemical name and symbol Physical appearance Cation of the compound Flame color
NaNO3Sodium nitrate Colourless crystal Na+ Yellowish Orange
NaClSodium chloride Colorless crystal Cl+ Yellowish Orange
LiNO3Lithium nitrate Colorless crystal Li+ Red
BaNO3Barium nitrate White crystal Ba² Bright yellow, lime yellow
Sr(NO3) 2Strontium nitrate White crystal Sr² Dark red
Cu(NO3)2Cupric nitrate Blue crystal Cu² Green, bluish green.
Ca(NO3) 2Calcium nitrate White crystal Ca² Redish orange
KNO3Potassium nitrate Colourless crystal. K+ Light purple
Unknown #1 Colorless crystal Red
Unknown #2 White crystal Redish orange
Unknown #1 is lithium nitrate, because it had the same physical appearance and same flame color as lithium nitrate.
Unknown #2 is calcium nitrate, because they share the same physical appearance and flame color.
A) Which part of the compound is responsible for the flame colour? How would you know?
The cation part of the compound is responsible for the flame colour. Because almost all of the different compound had nitrate as the anion, but they had different colours. The only compound which did not have nitrate, as the anion is sodium chloride. But it produced the same color as sodium nitrate, which showed that the color in which they produce was caused by sodium.
B) Which sample released the most energy? How would you know?
The sample, which released the most amount of energy, is potassium nitrate. Because the amount of energy light produces is depended on the frequency (colour) of the light, and potassium nitrate produced a light purple colour. According to the visible spectrum, a photon of purple had more energy than any other colour produced in this lab, because purple light has shorter wavelength (approximately 380-450 nm) and shorter wavelength means higher frequency which also means higher energy. Therefore we can conclude that potassium nitrate produced the most amount of energy when burned.