Basic Laboratory Techniques Flashcards
is the actual amount of material in an object and does not change with the environment on which it is located
Mass
is a force resulting from the interaction of the mass with the earth’s gravitational field and varies with location.
Weight
Different types of balances or weighing scales are available to measure the mass of a sample
Analytical Balance
Triple beam Balance
Top Loading Balance
have a complex system of electronic sensors to measure mass and are essential for weighing to milligrams quantity.
Electronic balances
uses counterweights to determine the mass of a sample in its pan.
Triple beam balance
____ of the balance is also essential to ensure accuracy of mass readings.
Periodic calibration
Graduated cylinders, pipettes, burettes and volumetric flasks are generally used for measuring
Volumes of liquids
pipettes and burettes are calibrated to deliver a
specific volume of liquids at a specified temperature.
is the curve formed at the upper portion of the liquid.
Meniscus
A ___ meniscus occurs when molecules of liquid are attracted more strongly with the surface of the container (adhesion)
concave
A ___ meniscus occurs when molecules of liquid are attracted more strongly with the surface of the container (adhesion)
concave
a ____ meniscus occurs when the molecules of liquid are more strongly attracted to each other (cohesion).
Convex
should be used in conjunction with a rubber bulb to draw up liquid
from a container.
Measuring pipette
the most basic of the three and has no needle valve that regulates gas flow.
Bunsen burner
have a needle valve below to regulate the gas supply.
Tirrill burner and Meker burner
differs in the presence of a screen on the top of the burner that forms many short, small uniform blue flames cones with a higher temperature. It is therefore more suited for glass blowing and other heating operations that require higher temperature.
Meker burner
Solid and liquid chemicals are usually kept in ____
reagent bottles
are used for light-sensitive chemicals to prevent them from decomposition.
Dark reagent bottles
are used for light-sensitive chemicals to prevent them from decomposition.
Dark reagent bottles
solid chemicals should be taken from a reagent bottle using a clean and dry
spatula
is a process that is used to separate an insoluble solid from a liquid
Filtration
insoluble solid is commonly termed as
residue or sediment
insoluble solid is commonly termed as residue or sediment and if it is a result of a precipitation reaction, it is called
precipitate.
insoluble solid is commonly termed as residue or sediment and if it is a result of a precipitation reaction, it is called
precipitate.
The liquid portion is (in filtration)
filtrate
is done to isolate a valuable residue that is to remove impurities and to recover filtrate as a valuable component
Filtration
can be cut into smaller size using a triangular file
Glass tubing
The glass tube is laid flat on the laboratory table and a _____ scratch at the point to be cut is made using the file.
circular
A ___ scratch is preferable to lessen the pressure needed to break the glass.
deeper
The sharp edges of the glass tube is polished by rotating it at the non-luminous portion of a laboratory burner’s flame ; the process is called
Fire polishing
