Activity 2 Flashcards
In case of a fire due to a gas leakage, immediately turn off the ___
To prevent spreading of the fire, cover it with ___ or ___
Gas Tank Regulator
Sand, wet cloth
Most Chemical spills are best handlled by quickly absorbing the wet material with ___ and then washing the area with ___
paper towels
water
To neutralize acid on clothing use ___
To neutralize base on clothing use ___
To neutralize any on desk use ___
dilute sodium bicarbonate solution
boric acid solution (50g/L)
solid sodium bicarbonate + water
Why do you never lay a stopper of a reagent bottle on the laboratory bench?
Because it will pick up impurities and contaminate the solutions
How do you transfer liquids to another container
Hold a stirring rod against the lip of the container holding the liquid
pour it down the rod which is touching the inner wall of the receiving vessel
A solution’s volume is read at which part of the meniscus?
The bottom of the meniscus
A Test tube should be no more than ___ full
An Erlenmeyer Flask should be no more than ___ full
A large beaker used as a bath must be no more than ___ full
one-third
one-fourth
one-fourth
What is ebullition?
A sudden violent outburst from a liquid
How do you stop bumping? (sudden formation of superheated liquid near flame)
the flame must directly be under the top of the stirring rod.
you may place a second supporting ring around the top of the beaker to prevent it from being bumped off
For the evaporation of liquids:
Nonflammable liquids are evaporated in a ___ with a ___
Flammable liquids are evaporated with a ___, perhaps with a ___
evaporating dish, gentle direct flame/steam bath
heating mantle/fume hood
How do you transfer a solid reagent?
Hold the bottle with the label against your hand, tilt, and ROLL
A liquid the supernatant can be decanted (poured off the top) when?
from a solid if there is clear separation
Using a beaker in decantation what can you do?
Can be tilted to allow the solid to settle at the side with an item
How fast does a centrifuge spin?
5000 to 25 000 revolutions
Centrifuge rules (4)
Never fill the centrifuge tubes to a height more than 1 cm from the top
label the centrifuge tubes to avoid confusion
Operate the centrifuge with even number of centrifuge tubes with equal volumes of liquid
Never manually stoop the centrifuge
Economical, how does Gravity filtration work?
Precipitate settles at the bottom
Wet the filter paper with a small amount of water or a liquid the precipitate is insoluble in
