Emission Spectroscopy

Observations

Name	Substance before heat	Substance during heat
Barium Chloride	White fine crystals	Yellow, green, orange
Calcium Chloride	White pellets “Styrofoam pellets”	Bright orange, bubbling and sizzling on stick
Lithium Chloride	White, fine, more of a powder than crystal	Bright Velvet Red
Sodium Chloride	White crystals, defined structure	Orange
Strontium Chloride	White crystals, Solid	Blue, bright red flame, over time the flame became more dull, and turned orange
Copper Chloride	Most blue crystals, some green crystals (from H2O)	Green, dark blue, light blue, orange, purple, also was sparkling
Potassium Chloride	White fine crystals	Purple, light blue color, some white
Unknown Substance 1	White fine crystals	Purple, white, blue, pink
Unknown Substance 2	Blue crystals, some green crystals (from H2O)	Green, blue, orange, purple, indigo.

Questions

1.     According to modern theory of the atom, where may an atom’s electrons be found?

The atom’s electrons can be found on the valence shells “clouds” outside the nucleus.

2.     How do electrons become “excited”?

Electrons become “excited” when a certain amount of energy is applied. In this case the energy came in the form of a flame (heat).

3.     How should the burner flame be adjusted?

Adjust amount of gas used to increase or decrease flame according to the flame color. If not enough energy is being applied add gas.

4.     Why should the wire loops used in the flame emissons tests be returned to their appropriate salt container?

They should be put in their appropriate salt container to avoid cross contamination between substances.

5.     How can a contaminated loop be cleaned?

      Commonly, dipping it into HCl, or a nitric acid can clean a contaminated loop. Following that you could rinse the loop off in distilled water. You can test it by putting it under a flame. If a flame color comes than you can tell it is not sufficiently cleaned.

6.     What is the identity of the unknown salt(s)?

Unknown 1 = Potassium Chloride

Unknown 2 = Copper Chloride

7.     Prior to its discovery on Earth, the existence of helium was first confirmed in the sun. Explain how this is possible.