Bunsen Burner Lab Bunsen Burner

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Bunsen Burner Lab Gas regulator knob Name: ______Period: ______Date: ______Score:______I. Background—Parts of the Bunsen burner Name of Part Function Barrel Air intake openings (holes) Needle valve Gas regulator knob Base Gas intake tubing Gas valve

II. Burner flame characteristics A) Close the air holes at the base of the burner. The flame now has a(n) ______color. This is called a luminous flame. With the crucible tongs, hold a dry porcelain evaporating dish in the tip of the flame for about a minute. A(n) ______color deposit of what appears to be ______forms on the dish. This deposit comes from the incompletely burned gas. B) Now open the air holes and note the change in the appearance of the flame. The flame now becomes a(n) ______color. This is called a nonluminous flame. (NOTE: If too much air is admitted, the flame may “strike back” and burn at the base. If a burner strikes back, the gas must be turned off, the air supply decreased, and the burner relighted.) Regulate the air and gas supply so that the flame is as colorless and quiet as possible. Clean the evaporating dish by means of water and a paper towel and hold the DRY dish in this nonluminous flame. Does the bottom of the dish now become coated as before with the luminous flame?______III. Structure of the Burner flame Reduce the height of the flame to about 5cm. Hold a wire device vertically in the flame for several seconds until the wires are glowing. Note the pattern where the metal glows. Hold the cardboard vertically in the flame for several seconds until a scorched pattern appears. DO NOT CATCH ON FIRE. Note the pattern in which the paper is charred. Draw the basic shapes of the patterns observed for each. Glowing wire pattern: Scorched Paper/Cardboard Pattern:

Carefully examine the nonluminous flame and locate each cone labeled in the above diagram before extinguishing the flame. Push a straight pin through a match just below the head. Suspend the match vertically in the barrel of the unlighted burner so that the head projects slightly above the barrel. Light the burner as you normally would. What happens to the match? ______. Hold a small glass tube diagonally with its lower end in cone B of the flame. Bring a flame to the upper end of the glass tube. What happens? ______.

IV. Analysis Questions

1) Which type of flame (reference terms from Part II) burns the cleanest?______a. Evidence to Support Claim:______2) Which cone from the above diagrams burns the hottest? ______a. Evidence to Support Claim:______3) Using your results from the match head in Part III, what does this suggest about the structure of the flame? ______

III. Structure of the Burner flame Reduce the height of the flame to about 5cm. Hold a wire device vertically in the flame for several seconds until the wires are glowing. Note the pattern where the metal glows. Hold the cardboard vertically in the flame for several seconds until a scorched pattern appears. DO NOT CATCH ON FIRE. Note the pattern in which the paper is charred. Draw the basic shapes of the patterns observed for each. Glowing wire pattern: Scorched Paper/Cardboard Pattern:

IV. Analysis Questions