The parts of the burner are the barrel, air holes, gas spud, gas inlet, gas regulator, and base

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DE LA SALLE SANTIAGO ZOBEL SCHOOL Ayala Alabang, Muntinlupa City

Name: Year & Sec.:

Teacher: Date:

Experiment No. 1 BUNSEN BURNER INTRODUCTION

Invented by Robert Wilhelm Bunsen in 1853, the Bunsen burner is now the most frequently used source of heat in the laboratory. It is designed so that gaseous fuel may be mixed with the correct amount of air to yield the maximum amount of heat. To use this burner properly and safely, it is essential that one understands its construction and the adjustme nts that can be made.

The parts of the burner are the barrel, air holes, gas spud, gas inlet, gas regulator, and base. The quantity of gas emitted by the burner is controlled by the gas regulator while the air needed for the combustion enters the small opening around the bottom of the barrel. The air is controlled by turning the barrel so as to make the air holes larger or smaller.

I. Objectives

A. To manipulate a Bunsen burner

B. To demonstrate the characteristics of a Bunsen burner flame C. To determine the hottest and coldest regions of the flame

II. Materials

Bunsen burner test tube rack

gas supply matches

2 test tubes with 10 mL water each stopwatch nichrome wire or copper wire (10 cm)

Hazard

The flame can cause fire and burns.

Precautions

1. To prevent fire, always follow correct procedure in lighting the burner. Know the location of the safety showers and fire extinguisher close to you.

2. The most common forms of laboratory accidents are burns. Be careful in handling a heated object. Make sure that the object is allowed to cool down before touching it. Your face, clothing, and hair should not be above or near the opening of the burner tube.

3. If a problem occurs, turn off the gas valve immediately.

III. Key Concepts (Cite references.)

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IV. Procedure

A. Nature of the Flame

1. Connect the tubing of the Bunsen burner to a gas outlet. Make sure that the gas valve, gas regulator, and air holes are closed. The rubber tubing must be free of holes to avoid leakage.

2. Turn on the main gas valve. Strike the match and bring alongside the barrel of the burner (about an inch below the nozzle) while turning the gas regulator on. Raise the lighted match toward the top until the gas ignites. Not e the color of the flame and the sound produced.

3. Hold a test tube containing 10 mL water on the tip of the flame. Using the stop watch, record the length of time it takes for the water to boil.

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4. After the test tube has cooled, rub your finger through the dark material at the bottom of the tube and record the appearance of the material on your finger.

5. Open the air holes. Note the color of the resulting flame and the sound produced.

6. Again, hold another test tube containing 10 mL water on the tip of the flame. Using the stopwatch, record the length of time it takes for the water to boil.

B. Temperature of the Flame

Using your tongs, get a 10-cm piece of nichrome/ copper wire and place it into the flame just above the barrel.

Record the color of the wire after it was heated for a few seconds at a specific region of the flame. Slowly move the wire upwards to various parts of the flame. The color of the wire reflects the temperature of the flame.

V. Data and Results A. Nature of the Flame

Condition of the Air Holes Color and Sound of Flame

Boiling Time of Water A. Air Hole Closed

B. Air Holes Opened

B. Temperature of the Flame

Region of the Flame Color of the Nichrome Wire Description of the Relative Hotness or Coldness of the

Region A. Triangular region just

above the tip of the barrel

B. Midway through the flame on top of the barrel

C. Tip of the flame

VI. Guide Questions (Copy and Answer)

1. Draw the Bunsen burner and label the parts. Describe function of each part.

2. Why should the rubber tubing be properly fitted to the burner and gas supply?

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3. If a match were placed in the cone close to the barrel of the gas burner, do you think it will ignite? Explain.

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4. Draw and describe the flame produced when the air holes were closed.

5. If the flame is luminous, what made it so?

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6. What is left at the bottom of the test tube after it was allowed to cool? What does it consist of? What does this imply about the combustion that took place?

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7. Draw and describe the flame when you slowly opened the air holes.

8. Explain why the flame may sometimes blow itself out.

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9. Draw the flame again in number 7. Identify the hottest part of the flame. How did you determine the hottest part of the flame?

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VII. Analysis of Data

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VIII. Conclusion

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IX. Application

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X. References

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Modified from:

Religioso, Teresita F. & Mendoza, Estrella E., Laboratory Manual in Chemistry, p. 2-5.

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DE LA SALLE SANTIAGO ZOBEL SCHOOL Ayala Alabang, Muntinlupa City

Name: Year & Sec.:

Teacher: Date:

Experiment No. 2 FLASHING ATOMIC COLORS

I. Objectives

A. To identity the metallic ions based on the colors they impart to a flame B. To demonstrate that electrons absorb and emit energy

II. Materials

6 aluminum boats box of matches

6 test tubes each containing 1 mL denatured alcohol and labeled as:

A. no salt D. with copper nitrate

B. with potassium nitrate E. with sodium chloride C. with lithium nitrate F. unknown

Caution: Do the experiment under a hood or in an open, ventilated space. Do not inhale the vapor. If the solution splashes on your skin, wash the affected area immediately.

III. Key Concepts (Cite references.)

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IV. Procedure

A. Transfer the content of each of the test tubes to the labeled aluminum boat.

B. Light the alcohol and observe the color of the flame produced.

C. Record your observation in the table below.

V. Data and Results

Metal in Salt Color of Flame

1. Potassium 2. Lithium 3. Copper 4. Sodium 5. Unknown

VI. Guide Questions

1. Explain why an element gives off light with a characteristic color when heated.

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2. How would you characterize the flame test with respect to its sensitivity?

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3. What difficulties may be encountered in the use of the flame test for identification of a metallic ion?

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4. What metal is present in the unknown sample? What is your basis for identifying your unknown sample?

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VII. Analysis of Data

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VIII. Conclusion

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IX. Application

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X. References

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Modified from:

Padolina, Ma. Cristina D, Ph. D, Laboratory Manual and Workbook in Chemistry, p. 39.

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