Presentation on theme: "Intro to Chem lab Equipment Weighing –Pan and analytical scales Liquid measure –Use of glassware, liquid meniscus Bunsen Burner –Construction, adjustments,"— Presentation transcript:
Intro to Chem lab Equipment Weighing –Pan and analytical scales Liquid measure –Use of glassware, liquid meniscus Bunsen Burner –Construction, adjustments, lighting Safety hardware –Eyewash fountain, fire blanket & extinguisher
Utility Pan-Scale Resolution 0.010 gram Maximum ≈ 1000 gram For routine lab work “good enough” for most purposes “Tare” feature useful Simply switch on NO chemicals on pan, use dish or paper
Analytical Scale 0.0001 gm resolution Maximum ≈ 200 gram For critical measure Sensitive to breezes Sensitive to heat “Tare” feature Use tweezers Fingerprints can matter NO chemicals on pan
Individual vs. Cumulative weighing Weigh empty vessel Tare Scale (m=0) Weigh 1 st item, record Re-Tare (optional) Remove 1 st item Weigh 2 nd item, record Repeat as required Each is independent Errors effect only one Weigh empty vessel Tare Scale (m=0) Weigh 1 st item, record Weigh 2 nd item, record Weigh 3 rd item, record Repeat as required Differences = item mass Saves time Cumulative error issue
Graduated Cylinders Use smallest cylinder suitable small volume = bigger influence, more accurate
Pipette and “Suction Bulb” Three 1-way valves, Exhaust + Fill + Drain
Reading Volume on Glassware Glassware calibrated to read at lowest part of surface “meniscus” Surface tension pulls liquid up side of glass Smaller diameters are more accurate, less volume per increment This example ≈ 6.7 ml
Burner Adjustments Wheel on bottom controls amount of gas –More gas when “unscrews” counterclockwise Upper collar controls air flow –Most air when slots are fully open Adjust 2 together for needed flow, best mix –2-color light& dark blue flame is optimum
Bunsen Burner gas-air mix left=lack of air (sooty, cooler), right=optimum mix (hottest)
Lighting the Burner “Scratcher” is common welder’s ignition tool Press flint to abrader then squeeze handle Tilting burner helps Use one burner to light another, easiest way Ask for help !
Counter-top utilities Electrical –120 volt household with GFI protection –Network outlet Natural Gas –Gas is “ON” with handle parallel to hose Water –Tap water at desktops, for cooling (not chem use) –Distilled water at back of room, gray plastic tap Vacuum –Next to gas, for speedy filtration
Fume Hoods Stinky stuff goes here ! Keeps experiment smells out of classroom Computer controlled, more air with greater opening … noisier too Sliding door is also a splatter shield.
Ice Maker Near Weighing Room Cooling baths for various experiments NO FOOD storage here. NOT a good idea to eat chemistry lab ice, could be contaminated !
Fire Extinguishers Red canisters on wall Powder smothers fire –“ABC” mix inside –Messy but effective Pull pin out, squeeze trigger to release pressurized contents Single-use, powder clogs release valve Pressure gauge should be in “green”
Fire Extinguisher safety pin & ring Twist and remove ring, squeeze handles to spray
Fire Blanket Used to put out clothing fires. Designed to smother fire, excludes oxygen Don’t become the smoking filling of a fire-blanket burrito !
Burns can be avoided! See posted story on chemistry lab accidents
Safety Goggles Required! Goggles offer protection from gas, liquid, solid Safety glasses only deflect flying objects
Eyewash Fountain & Shower Don’t experiment with it! No drain, will flood lab –May have a 15 min timer A conflict of regulations –Must have eye fountain –Spill might be hazardous –No drain avoids sewer system contamination. NO fun here –Cold water, naked students, wet floor! Emergency use only
Chem Lab Oven General drying –Experiment samples –Wet glassware Usually set at 110 o C Need to label which sample is yours, they all look alike
Broken Glass Container Cardboard box in lab Chipped, cracked, or broke glass goes here Do NOT use broken or cracked glassware, could be dangerous Minor chips may be repairable, show your instructor if in doubt.
Hazardous Materials, NFPA-704 Diamond Symbol in white for specifics (radioactive, don’t use water, etc.) Firemen might NOT enter area with danger value >2
Safety First! Have a GREAT semester in Chemistry! SAFETY FIRST is our #1 priority Bad examples follow –Possible candidates for “Darwin award”, for elimination of the unfit. –“don’t do these at home”
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