Using Flame Tests Lab

Question: How can the color of a flame be used to distinguish substances?

Hypothesis: If i burn different compounds, then the color of the flame will change.

Ind. Variable: Different compounds

Dep. Variable: Flame color

Ctrl. Variables: Flame source, height of compound in flame, amount of compound

Materials: 

Procedure:

  1. Light the bunsen burner.
  2. Dip the wire loop into the calcium chloride solution and then place the loop in the flame.
  3. Observe and record the color of the flame
  4. Clean the loop by dipping it into hydrochloric acid.
  5. Repeat steps 2-4 with the other solutions.
  6. When done with the 1-5, obtain the unknown solution from the teacher.
  7. Repeat steps 2-4 using the unknown solution.

Table:

Data Table for Using Flame Tests Lab

Solution

Flame Color

Correct Color

Number of E-

Calcium Chloride

Red

Bright Orange

20

Potassium Chloride

Purpleish-Orange

Purple

19

Boric Acid

Orange

Very Light Green

5

Copper(II) Sulfate

Green

Dark green

29

Sodium Chloride

Dark Orange

Yellow-Orange

11

Unknown

Pinkish-Orange

Purple

Identity of Unknown: Potassium Sulfate (20 E-)

Electrons:

Boron (very light green) = 5

Sodium (yellow-orange) = 11

Potassium (purple) = 19

Calcium (bright orange) = 20

Copper (dark green) = 29

Data Analysis:

When we burned out 6 different compounds, we saw very different flame colors. The difference in flame color is caused by each element’s unique electron configuration. When we burned the compounds, the head caused the electrons to jump from one energy level to another. We see the energy they give off as light and color when they jump.

Conclusion:

        After we burned the different compounds, the colors changed. We know this because boron, sodium, potassium, calcium, and copper all burn different colors from each other. Three errors that could happen were keeping the stick or loop in the fire for too long, recording an incorrect color, or not having enough of the chemical on the stick or loop. If I were to do this experiment again, I would have the substance be purer and not have much water in it.