chem120L stolen review

T/F: Food is not allowed in the lab, only drinks

False: anything you plan to ingest should not be brought into the laboratory (lab manual pg. 13)

T/F: The best first aid for acid, alkali, or other chemicals splashed on the skin, cuts, abrasions or burns is immediate flushing with large quantities of tap water

True (lab manual pg. 14)

How long should eyes be rinsed for if chemicals get in eyes?

Minimum of 10 minutes (lab manual pg. 14)

T/F: If fire alarm sounds, leave everything and immediately evacuate the building

False: turn off all services first (gas, electricity, water) and THEN leave the building via the exit indicated (lab manual pg. 15)

What to do if your clothing catches fire?

Stop, drop and roll. DO NOT RUN. (lab manual pg. 15)

T/F: When using a fire extinguisher, you should aim for the top of the flame

False: Aim for the base, sweep across slowly and evenly (lab manual pg. 15)

What is the proper technique of sampling a gas by odour (smelling chemicals)?

Wafting: fanning the chemical's vapours towards the nose with the hand after filling lungs with air (lab manual pg. 16)

T/F: Always pour acids into water while agitating, never pour water into acids

True (lab manual pg. 16)

What should be done if a chemical is spilled?

The spill should be immediately cleaned up and an instructor notified (lab manual pg. 16)

Which are the best methods of heating a flammable liquid:

a) Gas/open flame

b) Electric heating mantle

c) Steam bath

b) Electric heating mantle

c) Steam bath

*never use an open flame to heat flammable liquids (lab manual pg. 16)

What are the only chemicals that are allowed to be disposed of down the drain?

None (lab manual pg. 16)

T/F: Broken glass should be immediately carefully discarded in the garbage closest to your workbench

False: broken glass should be discarded into a specially marked "Broken Glass" container (lab manual pg. 17)

Which are acceptable to use for cleaning up broken glass:

a) Brush & dustpan

b) Cardboard

c) Paper towel

d) Cotton

a) Brush & dustpan

b) Cardboard

d) Cotton

*Do not use paper towel to clean up broken glass

(lab manual pg. 17)

Which orientation should tubing and long glassware be carried: vertically or horizontally?

Vertically (lab manual pg. 17)

T/F: Pipettes with shortened/ragged ends should simply be discarded

True (lab manual pg. 17)

Whats the difference between accuracy and precision?

Example: a clock that displays hours, minutes and seconds is very precise, however if it's an hour behind then its not very accurate, whereas a grandfather clock showing the correct time would be considered accurate, though not as precise as the clock with seconds.

All in all: accuracy has to do with deviation from the true value, whereas precision is to do with the extent of certainty in a measured value.

T/F: When weighing by difference, the initial weighing beaker must be both clean and dry

True (lab manual pg. 103)

T/F: When weighing by difference, the three Erlenmeyer flasks used must be both clean and dry

False: they must be clean, but do not need to be dry as they never touch the balance (lab manual pg. 103)

What can be used to lift the weighing beaker when weighing by difference:

a) Your hands with gloves

b) Paper strip

c) Your bare hands

b) Paper strip (lab manual pg. 103)

T/F: When weighing by difference, it's unnecessary to zero the balance

True (lab manual pg. 103)

Which of the following are the two advantages of weighing by difference:

a) Only n - 1 weighings are required to prepare n samples

b) The titrating flasks don't need to be dry, only the weighing beaker

c) The weighing beaker doesn't need to be dry, only the titrating flasks

d) Only n + 1 weighings are required to prepare n samples

b) The titrating flasks don't need to be dry, only the weighing beaker

d) Only n + 1 weighings are required to prepare n samples

(lab manual pg. 103)

T/F: When weighing by difference, it does not matter if exactly the same amount is weighted into each flask

True (lab manual pg. 103)

T/F: When quantitatively transferring chunky solid, you can simply use clean, dry tweezers (called forceps) to move it to the receiving vessel

True (lab manual pg. 104)

When quantitatively transferring a powdered/crystallized solid, samples can be weighed on which of the following:

a) Weighing paper

b) Weighing boat

c) Clean, dry beaker

a) Weighing paper

b) Weighing boat

c) Clean, dry beaker

(lab manual pg. 104)

T/F: When quantitatively transferring a liquid or wet sample, at least three rinsings are recommended to ensure none of the sample remains in the dispensing vessel

True (lab manual pg. 104)

When quantitatively transferring a liquid, what applies if a funnel is used to aid in the transfer:

a) The funnel should be rinsed with solvent, and the rinsings added to the receiving vessel

b) The funnel should be rinsed with DI water, and the rinsings added to the receiving vessel

a) The funnel should be rinsed with solvent, and the rinsings added to the receiving vessel (lab manual pg. 104)

What should be used to help pour solution into a burette for rinsing:

a) A small plastic funnel

b) A pipette

c) A small beaker

a) A small plastic funnel (lab manual pg. 105)

T/F: It's more efficient for burettes be rinsed vertically, as it allows gravity to do most of the work

False: when rinsing a burette, hold it in a nearly horizontal position and rotate it so that the solution contacts the inner surface (lab manual pg. 105)

T/F: When rinsing a burette, three rinsings should be performed in total.

True (lab manual pg. 105)

How much solution should be added to a burette to rinse:

a) 5-10 mL

b) 10-15 mL

c) 15-20 mL

d) 20-25 mL

a) 5-10 mL (lab manual pg. 105)

After filling the burette with solution, why should you should open the stopcock briefly?

To displace all the air from the tip (lab manual pg. 105)

Readings on the burette should be measured to the nearest:

a) 1 mL

b) 0.1 mL

c) 0.01 mL

d) 0.001 mL

c) 0.01 mL (lab manual pg. 105)

T/F: Measurements from the burette should be made from the top of the liquid meniscus

False: measurements should be made from the bottom of the meniscus (lab manual pg. 105)

If you are too short to get on a level with the meniscus on a burette, which of the following is the proper solution:

a) Do not disturb the burette; stand on a stool so that your eye-line meets the meniscus

b) Lower the burette in its clamp until the tip nearly touches the tabletop

b) Lower the burette in its clamp until the tip nearly touches the tabletop, do not stand on a stool (lab manual pg. 105)

T/F: When titrating with a burette, the burette tip should extend 2-3 cm into the titration flask

True (lab manual pg. 106)

When titrating with a burette, what should you be doing with the flask as solution is added from the burette?

Swirling continuously (lab manual pg. 106)

T/F: When titrating, NaOH can be used to rinse the inner walls of the flask

False: DI water can be used to the rinse the inner walls of the flask (lab manual pg. 106)

Which of the following should be used to clean the burette after use:

a) DI water

b) Solution used in the burette

c) Cleaning solution

a) DI water (lab manual pg. 106)

When it is the liquid that is of interest, which method of filtration is most preferred:

a) Gravity filtration

b) Vacuum filtration

a) Gravity filtration (lab manual pg. 106)

Which is faster: gravity or vacuum filtration?

-Vacuum filtration is faster because the solution is forced through the filter paper by the application of reduced pressure (lab manual pg. 107)

T/F: You can check the suction of your vacuum filtration system by simply placing your hand over the Buchner funnel to feel for suction

True (lab manual pg. 107)

T/F: When vacuum filtering, filter paper should be wet with DI water to seal to the funnel

True (lab manual pg. 107)

Is it necessary to intentionally pour solution slowly into Buchner funnel when vacuum filtering?

Yes; pouring solution slowly will prevent the filter paper from floating upwards & allowing solids to be drawn into the flask (lab manual pg. 107)

When vacuum filtering, the solution should never fill more than:

a) 1/3 of the Buchner funnel

b) 1/2 of the Buchner funnel

c) 2/3 of the Buchner funnel

d) 3/4 of the Buchner funnel

c) 2/3 of the Buchner funnel (lab manual pg. 107)

T/F: When using a volumetric (transfer) pipette, the proper way to clean the suction bulb is by rinsing it with DI water and wiping it dry with a paper towel

True (lab manual pg. 108)

T/F: When draining a pipette, you can use the suction bulb to blow the liquid out of the pipette

False: always allow the liquid to drain by gravity, don't blow it out (lab manual pg. 109)

Why does wiping the tip of a pipette allow it to be reusable with the same solution for up to two hours?

-It removes adhering solution, which would otherwise evaporate and leave a contaminating residue (lab manual pg. 109)