Chem: Lab Quiz #1- Glassware and Pipetting

type A glassware; resistant to heat, corrosion, thermal shock; mechanical strength and chemical resistance are well balanced

high thermal resistant glassware (borosilicate)

glassware strengthened chemically rather than thermally; radiation resistant

high silica glass

used for working with strong alkaline solutions; aka "soft glass"

high alkaline resistant glass

glassware with an amber color thus reducing the amount of light transmitted through the glass; used for substances sensitive to light

low actinic glass

most inexpensive glassware, but may release alkali into solutions

standard flint/soda lime glass

safe glassware, greatly reduced the need for cleaning glassware

disposable glass

tall flask with slender neck and pear-shaped body; used for preparing a solution of a known volume

volumetric flask

flask used for preparing a solution of known volume; good surface area for mixing

ehrlenmeyer flask

flask shaped like a drinking glass; *least accurate*; used to simply hold stock solution or diluents for short-term storage or during laboratory procedures

beakers

flask with multiple volume gradations; calibrated to-deliver; good for measuring unknown volume

graduated cylinders

What is the difference between measuring and transfer pipettes?

Measuring (aka serologic)

- Used to deliver multiple volumes

- Less accuracy of measurement

- Blow out

Transfer (aka volumetric)

- Used to deliver one volume

- High degree of accuracy, class A

- Drain out

What is the difference between "to deliver" and "to contain"?

To deliver, blow out: has etched rings and last drop needs to be blown out

To contain: for used for highly viscous fluid

What is the correct technique for manual pipetting?

Hold one fourth inch from bottom

Use index finger

Wipe before adjusting volume

Press tip adjacent to container when dispensing

Use the pipette that is closest in size to the volume you want to deliver

What are the functional parts of a micropipette?

Plunger button, tip ejector button, volume adjustment dial, digital volume indicator, shaft, attachment point for disposable tip

What are the correct techniques for micropipetting?

Immerse to proper depth, tip should remain in liquid until entire amount has been aspirated, do it slowly

Why are micropipettes most accurate at RT?

because they are calibrated at RT

How often do you calibrate micropipettes?

every 6 months

What are the two methods for calibrating micropipettes?

Gravimetric analysis: most common; dispensing water into a balance

Colorimetric method: uses precise measurements of colored water and spectrophotometric analysis