Chemistry Honors Lab: Flame Test

Lab: Flame Test

In this lab, my group and I burned wooden sticks that soaked up many chlorine compounds over a bunsen burner.  Different chlorine compounds produced different shades of light.  We were to compare the results of the known compounds with two unknown substances and predict what they were.  My group decided, that since Unknown #1 had a red shade that the substance we strontium chloride.  We also determined that since Unknown #2 had a light lavender shade that the substance was potassium chloride.  Below are the answer to the pre-lab questions.

1) What is the difference between ground state and an excited state?

The ground state is when the electron configuration of an atom/element are in it's most stable and lowest energy state.  The excited state, on the other hand, is when the electron configuration is unstable and electrons are higher in terms of energy and will eventually calm down and return to the ground state.

2) What does the word "emit" mean?

Emit means that something, whether it be a photon or any amount of energy, is being created and dispersed away from it's source.

3) In this experiment, where are the atoms getting their excess energy from?

In this case, the "excess energy" is coming from the flame created by the bunsen burner.

4) Why do different atoms emit different colors of light?

Electrons, when heated, jump up to higher energy levels, but they don't stay there for long.  When they fall back down, they release their energy as photons.  For every element, the "quantized" amount of energy to go from one level of energy to the next is different.  That amount of energy determines the color of the light emitted.

5) Why is it necessary for each station to have separate wooden splints for each individual flame test?

After using on splint, the wood would be "contaminated" with that solution.  If we were to try and resoak that splint, the results of the following test would be skewed.  The reason being is that we wouldn't know which element is reacting.

Flame produced by Copper Chloride (CuCl₂)