Laboratory Equipment and Safety: Flashcards
Revise hazard pictograms, safe habits, the precision of common glassware and how to read a burette.
Laboratory Equipment and Safety: Flashcards
- QuestionWhat does the flame pictogram mean? And the flame over a circle?Answer
Flame: flammable. Flame over circle: oxidizer (makes fires burn more fiercely).
- QuestionWhat does the corrosion pictogram mean?Answer
The substance destroys skin, eyes or metals (e.g. concentrated acids, sodium hydroxide).
- QuestionWhich signal word shows the more severe hazard: Danger or Warning?Answer
Danger.
- QuestionWhere do you find full hazard and handling information for a chemical?Answer
On its safety data sheet (SDS), as well as the label.
- QuestionHow should a concentrated acid be diluted?Answer
Add the acid slowly to the water, never water to acid: mixing releases heat and can make it spit.
- QuestionWhich glassware delivers one exact, fixed volume?Answer
A volumetric pipette (e.g. 25.00 mL, ±0.03 mL).
- QuestionWhy should you not measure volumes with a beaker?Answer
Its marks are only approximate (about ±5 %).
- QuestionGive the formula for percent uncertainty.Answer
Percent uncertainty = (uncertainty ÷ measured value) × 100 %
- QuestionWhich part of the meniscus do you read for water, and from where?Answer
The bottom of the meniscus, with your eye level with it (to avoid parallax error).
- QuestionA burette reads 0.50 mL at the start and 23.35 mL at the end. What is the titre?Answer
23.35 mL − 0.50 mL = 22.85 mL
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