Presentation on theme: "1.2 Let’s Play Safe 1.3 Drawing Scientist Tools 1.4 Using the Bunsen Burner."— Presentation transcript:
1.2 Let’s Play Safe 1.3 Drawing Scientist Tools 1.4 Using the Bunsen Burner
Refer to page 5 of your notes The science laboratory can be a dangerous place if you are not careful. There are certain rules that must be followed for your own safety and for the safety of everyone else in the room.
Activity Time (page 6) Look carefully at the drawing below and find all of the rules that are being broken in the science laboratory
Mixing chemicals without the teachers’ permission Throwing rubbish / pouring chemicals into the washing basin Eating in the science lab. Loose papers close to the Bunsen flame Smelling chemicals without teachers’ permission Playing and pushing in the lab Test tube pointing to own’s face and partner’s face Pour substance down the sink
Hazard Symbols Some of the chemicals that you use in the laboratory are potentially harmful. Hazard labels are used to label such chemicals to alert you to the type of hazards present. This will be done in the lab.
Refer to page 7 of your notes 1.All laboratory apparatus should be drawn in outline only and in their correct proportion. 2.Do NOT draw a 3-dimensional outlines for laboratory apparatus. 3.Draw sectional diagrams of the apparatus that your teacher shows you. 4.You may make use of the template of laboratory apparatus sold in the school bookstores or included in your mathematical set.
Laboratory Apparatus Diagram Purpose For transferring liquids into a flask For supporting apparatus during experiments For separating an insoluble solid from a liquid with the help of a piece of filter paper Name thistle funnelretort standfilter funnel
Laboratory Apparatus Diagram PurposeFor separating an experimental set- up from the outside environment For supporting apparatus during heating For containing chemicals or collecting liquids Namebell jartripod standbeaker
Laboratory Apparatus Diagram Purpose For containing chemicals when preparing gases if the process requires no heating For containing or heating small amount of substances For measuring a volume of liquid to an accuracy of 0.5 cm 3 Name flat-bottomed flasktest tubeMeasuring Cylinder
Laboratory Apparatus (pg7) Diagram Purpose For containing chemicals or collecting liquids For containing water when collecting gases For preparation of gases if the process requires heating Name conical flaskwater troughround-bottomed flask
Laboratory Apparatus Diagram Purpose For evaporating a liquid from a solution For collecting gasesFor heating solids directly over a flame Name evaporating dishgas jarCrucible
Let’s try(page 7) Name the apparatus C – H in the following figure. retort stand thistle funnel round-bottom flask tripod gas jar Water trough
To raise the flame to a suitable height for burning To enable the gas to rush out from the gas supply and to draw in air Gas Tap To control the flow of gas to the Bunsen Burner To control the amount of air entering the burner by opening or closing the air- holes To control the air entering the Bunsen Burner Refer to page 8 of your notes The Bunsen Burner We will covering the Bunsen burner in the lab.
Refer to page 8 of your notes Types of flames almost colourless zone of complete combustion Bunsen burner dark zone of unburnt gas blue zone of partial combustion hottest part orange zone of incomplete combustion A luminous flame A non-luminous flame 1.occurs when the air-holes are open, allowing air into the burner 2.blue 3.burns steadily 4.hotter than the luminous flame 5.hottest part of the flame is just above the tip of the blue zone. 1.occurs when the air-holes are closed and very little air is allowed to mix with the gas 2.carbon particles are deposited on apparatus 3.orange 4.appears flickering and unsteady 5.not very hot Hottest
Refer to page 9 of your notes STRIKEBACK 1.occurs when there is too much air entering air-hole 2.instead of burning at the top of the barrel, the gas burns at the jet 3.when a strike back occurs, turn off burner immediately jet http://www.youtube.com/watch?v=AWnSSvdMp5g
Refer to page 9 of your notes HEATING LIQUID IN A BEAKER 1.put wire gauze on tripod stand 2.put beaker of liquid on it 3.light Bunsen burner and then push it under the tripod stand 4.turn off burner when the liquid reaches required temperature
Refer to page 9 of your notes HEATING LIQUID IN A TEST-TUBE 1.hold test-tube with test-tube holder 2.ensure that the mouth of the test-tube is pointing away from myself and others 3.slant test-tube at an angle of about 45 o and heat it in the hottest part of a Bunsen flame 4.move the test-tube through flame 5.liquid to be heated should occupy no more than one-third test-tube