Laboratory equipment

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Erlenmeyer Flasks and Beakers

• Erlenmeyer flasks and beakers are used for mixing, transporting, and reacting, but not for accurate measurements. The volumes stamped on the sides are approximate and accurate to within about 5%.

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Graduated Cylinders

• Graduated cylinders are useful for measuring liquid volumes to within about 1%. They are for general purpose use, but not for quantitative analysis. If greater accuracy is needed, use a pipette or volumetric flask.

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Burets• A buret is calibrated to

deliver volumes indicated between graduations. Delivery is completed only after the drop of liquid adhering to the burette tip is removed (by touching the tip to the inside of a glass vessel). A buret is used to deliver solution in precisely-measured, variable volumes. Burets are used primarily for titration, to deliver one reactant until the precise end point of the reaction is reached.

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Pipettes

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Top-loading Balance• Use a top loading balance to weigh solid material

when a precision of 0.1 g is adequate. For more accurate mass measurements or small amounts, use an analytical balance.

Using a Top-loading Balance• (a) Check if the balance is turned on. If not, press the

on/off button and wait until the display reads 0.0 g• (b) Place a container or large, creased weighing

paper on the balance pan. Push tare button to zero the balance.

• (c) Carefully add substance to the container or paper. Record mass.

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Analytical Balance• An analytical balance measures masses to within 0.0001 g. Use

these balances when you need this high degree of precision.

Using an Analytical Balance• (a) Turn the balance on by pressing the control bar. The display

lights up for several seconds, then resets to 0.0000.• (b) Place creased small weighing paper on the balance pan.• (c) Close the sliding glass doors. • (d) Press the control bar to cancel out the weight of the container

or paper. The display will again read 0.0000.• (e) Carefully add the substance to be weighed up to the desired

mass. Do not attempt to reach a particular mass exactly.• (f) Before recording the mass, close the glass doors and wait

until the stability detector lamp goes out. Record mass of solid.

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Analytical BalanceNotes• Don't pick up tare containers with bare hands since your

fingerprints add mass. Use Kimwipes or tongs to prevent this.

• Don't lean on the bench while weighing.• Do record the mass of your container, if you will need it

later.

Clean-up• Use the brush provided to clean spills in the weighing

chamber. Discard any disposable tare containers, weighing paper, or Kimwipes in the nearest wastebasket.

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Analytical Balance Analytical Balance