Construction and function of a Bunsen burner

Transcription

1 Teacher's/Lecturer's Sheet Construction and function of a Bunsen burner (Item No.: P ) Curricular Relevance Area of Expertise: Chemie Education Level: Klasse 7-10 Topic: Anorganische Chemie Subtopic: Luft und Verbrennungen Experiment: Aufbau und Funktion eines Bunsenbrenners Difficulty Preparation Time Execution Time Recommended Group Size Easy 10 Minutes 10 Minutes 2 Students Additional Requirements: Experiment Variations: Keywords: Bunsen burner, function of Bunsen burner Task and equipment Information for teachers Learning objectives The Bunsen burner is based on the principle of adjustable gas combustion with air supply. By varying the quantity of air supplied, different burner temperatures can be achieved. Notes on set-up and procedure Preparation To keep the quantity of escaping residual gas as low as possible, shut off the main gas valve, or its equivalent, prior to the class hour and disconnect the burners from the gas supply. Then air the room well! Remarks on the students' experiments After the students have reassembled their Bunsen burners, you should check them for completeness and functionality in any case. The porcelain dish must not be heated too long because the soot formed will otherwise disappear again. Hazards Disconnect the Bunsen burner from its gas supply before disassembling it. If residual gas flows out, air the room well! If cartridge burners are employed, use only the domed, upper part. Do not use any filled gas cartridges for the examination! Wear protective glasses! Remarks on the method

2 Teacher's/Lecturer's Sheet The introduction to the use of the burner should be performed at the beginning of the instruction in chemistry. In this respect, this experiment is a review, but in the evaluation it goes far beyond a simple explanation of the burner's function, as here the reasons for the different determined functions are referred to known and consolidated facts. The construction and function of a welding torch can be discussed as early as the compilation of (the transfer) Exercise 2.

3 Construction and function of a Bunsen burner (Item No.: P ) Task and equipment Task How is a Bunsen burner constructed? Investigate the construction and mode of operation of a Bunsen burner.

4 Equipment Position No. Material Order No. Quantity 1 Protecting glasses, clear glass Wire gauze with ceramic, 160 x 160 mm Crucible tongs,200mm,stainl.steel Porcelain dish, 75ml, d = 80 mm Bunsen burner,natural gas, DIN Safety gas tubing, DVGW, sold by metre Cotton wool, white 200 g Butane burner f.cartridge Butane catridge CV 300 Plus, 240 g

5 Set-up and procedure Set-up Hazards Separate the Bunsen burner from any existing gas supply before disassembling it. If residual gas flows out, air the room well! If cartridge burners are employed, use only the domed upper part. Do not use any filled gas cartridges for the examination! Wear protective glasses! Procedure Procedure Carefully take a Bunsen burner completely apart (do not use force!) (Fig. 1 -Fig. 3). Fig. 1 Fig. 2 Fig. 3 Lay the individual components carefully next to one another on the working surface (Fig. 4). Name them and note which task they fulfil tor the burner's functioning (see evaluation sheet).

6 Fig. 4 Put the burner back together. Have the teacher check it for completeness and functionality. Close the air supply valve (Fig. 5) and ignite the inspected burner and observe the flame. Then hold the bottom of the porcelain dish in the flame for approximately 10 seconds with the crucible tongs (Fig. 6). (Abb. 6). Fig. 5 Fig. 6 Allow the dish to cool (Fig. 7) and examine it. First, open the air supply slightly (Fig. 8), then completely (Fig. 9). Repeat the experiment in each case with the porcelain dish (clean it before each repetition). Then pick up a piece of cotton wool and move it toward the non-luminous burner flame (Fig. 10).

7 Fig. 7 Fig. 8 Fig. 9 Fig. 10

8 Report: Construction and function of a Bunsen burner Result - Observations 1 Copy the cross sectional diagram of the burner's construction. Result - Observations 2 Name the individual parts, and state their function.

9 Result - Observations 3 Note your observations. Result - Table 1 Note your observations and then transfer the data into Table 1. Closed Slightly opened Air supply Fully opened Type of burner flame Porcelain dish 1 1 1

10 Evaluation - Question 1 Describe the different burner flames and the processes occurring on the porcelain dish. Using this information, explain how one can achieve the highest possible temperature of the burner's flame. Evaluation - Question 2 Which substances would considerably increase the temperature, if supplied?