P  sci7-9_sc7_ch1_presentation_done_bunsen burner prac
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P sci7-9_sc7_ch1_presentation_done_bunsen burner prac

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P sci7-9_sc7_ch1_presentation_done_bunsen burner prac Presentation Transcript

  • 1. Laboratory Techniques: Using a Bunsen Burner Introduction: Used in laboratories to heat things. A Bunsen burner can produce 3 different types of flames: The "coolest" flame is a yellow / orange color (300°C). It is never used to heat anything, only to show that the Bunsen burner is on. It is called the safety flame. The medium flame, the blue flame or the invisible flame (500°C) is difficult to see in a well-lit room. It is the most commonly used flame. The hottest flame is called the roaring blue flame. Has a light blue triangle in the middle and it makes a noise (700°C).
  • 2. • Flame types of Bunsen burner depending on flow through the throat holes (holes on the side of the Bunsen burner ). 1. air hole closed (Safety flame) 2. air hole half open 3. air hole nearly fully open 4. air hole fully open (Roaring Blue Flame)
  • 3. Lighting the Bunsen Burner • Step 1 Check for safety - long hair tied back, safety glasses on, books and papers away from the flame, heat- proof mat, apparatus set up not too close to the edge of the table...
  • 4. • Step 2 Look at the air hole. Check that the air hole is closed. The hole can be adjusted to let in more or less air by turning the collar
  • 5. • Step 3 Light the match. Some people prefer to turn the gas on and light the match after. The problem is, if the match breaks or goes out, the gas is leaking out of the tap while you get a new match.
  • 6. • Step 4 Light the Bunsen burner. Turn on the gas tap. To turn it on, first pull up, then turn the tap anti-clockwise. This is a safety feature so the taps are not accidentally pushed open. Approach the match to the top of the Bunsen burner (from the side.
  • 7. • Step 5 Adjust the flame by turning the collar so that you have the appropriate flame for the experiment (usually the medium blue flame).
  • 8. • Don't burn yourself! The only part of a Bunsen burner which gets hot is the top. The rest of it is safe to touch. The collar, for example is safe to touch so that the flame can be adjusted at any time, especially when the Bunsen burner is on.
  • 9. • Anything above the flame can get very hot: the wire grill, the top of the tripod, any glass beakers and solutions you heat up. • Since hot glass and cold glass look the same and hot metal looks the same as cold metal, you should always presume that something is hot. • Touch it lightly and quickly to find out its temperature or pick up things with metal tweezers to be sure not to get burned.
  • 10. • An efficient, hot flame has an inner cone and a pale-blue outer. • The part immediately above the barrel is cool, at just a few hundred. • Above this part of the flame, you will see a neon-like blue loop. This 'loop' is called the inner cone. The inner cone is quite hot. The top of the inner cone is the hottest part of the flame. • Above the inner cone is a pale blue, almost transparent layer called the outer cone. The outer cone is still quite hot.
  • 11. Word Bank: air hole barrel base gas tubing hottest part of flame inner blue cone of flame outer, non-luminous flame regulating collar