Chem Notes Ch 1 Flashcards
Beaker
Wide-mouth vessel with a spout at the top rim, different sizes, not accurate for measuring volumes. Heating, stirring, mixing solutions
Graduated cylinder
For general measurement of volume of liquid. Narrow and tail container, with measurement markings. Read bottom of meniscus
Erlenmeyer Flask
Conical flask with narrow necks and wider base. For mixing, heating and stirring solutions. Not accurate for measuring volumes. Preferred over beaker for mixing because it minimizes risk of spilling and splashing. Used during titrations.
Volumetric flask
Round flask with a flat bottom. Long and narrow neck. Used to reach specific volume of liquid, indicated by small marking on the neck. Often closed by cap to prevent evaporation and allow for vigorous shaking. Used for preparing or diluting a chemical solution.
Boiling flasks
Round bottoms, long neck. Used to swirl and heat
liquids. Clamp required to keep it in position. They cannot be used to measure the volumes of liquids.
Pipettes
Can be graduated or electronic. The most precise glassware for measuring the volume of a liquid. Variety of sizes. Used to transfer a specific volume of liquid to a container.
Burets
Highly accurate. Used to dispense highly accurate volumes of liquid. In titrations, used to deliver a titrant to a solution. Long, graduated glass tubes with a very narrow opening at the bottom. Stopcock is positioned right
above the opening and is used to control the amount of liquid released.
Test tubes
Glass tubes with one open end and a round, closed end. Holds small volumes of samples and can be used for mixing. Used to compare different samples qualitatively. Can be heated and cooled or used to store a
solution over a period of time. The open end can be capped.
Droppers
Small glass tubes with rubber bulb on one end. Used to deliver a liquid (usually an indicator), in a drop-wise fashion.
Bunsen burners
Metallic apparatus that produce an open flame for heating purposes. Connected to natural gas source by rubber tubing and have a valve that controls gas flow, and a collar that can be rotated to adjust airflow. Amount of gas provided to Bunsen burner is related to size of the flame. Light the Bunsen burner with a striker to ignite the flame.
pH meter
Accurately measure pH of a solution. Can be used in acid-base titrations. Should always be calibrated prior to use.
Digital balance
Accurate mass measurements
Volumetric
Glassware that has a single marking that indicates a
specific volume. These are generally more precise than graduated glassware.
Graduated
Any glassware that has several markings indicating different volume levels.
Order of precision from most precise to the least precise
Pipettes > Burets/Volumetric Flasks > Graduated Cylinders > Beakers/Erlenmeyer Flasks
Measuring the mass of a sample
First, tare the weighing paper or glassware that the sample will be placed on, before adding the sample and weighing on a digital balance.
Titration
Delivers drop-by-drop volumes of a titrant to another solution
through a buret. Measures the volume of titrant needed to react completely with the other reagent.
Indicators that are known to change colour near an equivalence point of a
given reaction are added to solution to mark the end of the titration. The pH of a solution can also be observed throughout the titration to look for large jumps in pH and
for periods of stabilization (buffer zones).
Equivalence point
The point at which the added titrant has completely reacted
with the reagent
Endpoint
Point at which an observable property (e.g. colour change) occurs and this is associated with either being at or near the equivalence point.
Titration error
Any deviation of the endpoint from the equivalence point
Centrifugation
Centrifuge instrument separates different parts of a mixture. Spins mixture at very high speeds. Centrifugal force acts upon heavier components of the mixture (solids), such that they move towards the bottom of the vessel and form the pellet. After centrifugation has finished, we separate the liquid supernatant from the solid pellet by using either a pipette, decanting the liquid or filtration. Simple decantation involves pouring the liquid out of the original vessel, leaving the solid behind.
Calorimetry
Measures amount of heat
energy released or absorbed during a chemical reaction. The change in heat can determine if reaction is exothermic or endothermic.
Systematic errors
Consistent shifts in one direction of a measurement that result from faulty equipment or an error in
the procedure
Random error
Errors not consistent but can vary in either direction. Result of human error
Percent error of an experimentally derived value and a known literature value
[(experimental - actual)/actual] | * 100%
Safety Shower
Delivers a continuous stream of water to any student who has been extensively splashed with toxic or corrosive chemicals. This can also be used on students whose clothing may have caught on fire.
Eye Wash Station
Treat any splashes of chemicals (acid, base, etc.) in or near the eyes. Thoroughly rinse the eyes by keeping both of your eyes open.
Fume Hood
Provide proper ventilation in an enclosed space such that it minimizes exposure to harmful vapors or fumes from any volatile substances you may be working with. Cover any containers containing
volatile substances with a watch glass, when not in use.
Fire Extinguishers
Aim at the base of the fire. Position yourself in between the fire and the exit. Should only be used for solvent or electrical fires and not those resulting from paper or wood.
Lab Coats
Always worn during the laboratory. If you get chemicals on your skin, rinse with lots of water and seek medical attention if needed. Wear closed-toe shoes.
Safety Goggles
Always worn during the laboratory. Avoid wearing eye contacts in the lab, as dangerous fumes can concentrate under the contacts and cause complications.
Rubber or Disposable Gloves
Should be worn when dealing with any potentially harmful chemicals
Broken Glass Container
Broken glass should be cleaned up as soon as possible, with caution, using a dustpan
Disposal of Solutions
Acids, alkalis, or other water miscible solutions can be flushed down the drain with copious amounts of water. Organic and other water immiscible chemicals should NOT be flushed down the drain but instead disposed of in the appropriate waste bin in the laboratory.
