CHEM 120L EXAM FLASHCARD EXAM
WITH CORRECT QUESTIONS AND
ANSWERS 2025
- Fire extinguishers (type ABC) - CORRECT-ANSWERSIn hall outside chem lab. Use for
class A (normal combustible material), B (gas, grease, oil), or C (electrical) fires.
- PASS: pull pin, aim low, squeeze handle, sweep slowly.
- Most dangerous thing in the laboratory - CORRECT-ANSWERSChemical vapours - can
be toxic, flammable, both.
- Proper way to combine water and acid - CORRECT-ANSWERSPour acid into water, not
other way around!
- Accuracy of a beaker - CORRECT-ANSWERS+-10%
- Accuracy of an Erlenmeyer - CORRECT-ANSWERS+-5%
- Accuracy of a graduated cylinder - CORRECT-ANSWERS1 decimal place?
- Accuracy of a volumetric pipette - CORRECT-ANSWERSDepends on what size, it's +- a
certain amount of mLs. 10mL = +-0.01ml.
- They are most accurate because of the small meniscus created by the narrow shape,
leading to less error.
- Accuracy of a volumetric flask - CORRECT-ANSWERS2 decimal places
- Accuracy of a top loading balance - CORRECT-ANSWERS2 decimal places
- Accuracy of an analytical balance - CORRECT-ANSWERS4 decimal places. Objects
need to be the same temp as the balance (otherwise it will form convection currents and
appear lighter) and all doors must be shut!
, - Quantitative transfer - CORRECT-ANSWERSSolid, 1 piece -> forceps, prevents
contamination
- Solid, powder -> use weighing boat/paper, tare and then add powder. Tip powder into
receptacle, tap, and rinse with some solvent to ensure everything is transferred. Or, put
the clean dry beaker on the scale and tare.
- Liquid -> Pour into receiving vessel, then rinse dispensing vessel (and any transfer
equipment, like a funnel) 3 times with solvent and add that to receiving vessel as well.
- Vacuum filtration - CORRECT-ANSWERSMake sure no cracks/chips, place rubber
stopper and Buchner funnel, wet the filter paper that is added to Buchner funnel to create
a seal. Never fill Buchner funnel more than 2/3.
- Most common natural sources of copper - CORRECT-ANSWERSChalcopyrite,
chalconite, and bornite. Must be purified from these ores.
- % yield - CORRECT-ANSWERSactual yield/theoretical yield x 100
- Only considers how much desired product is obtained, ignores side products.
- First reaction in copper lab - CORRECT-ANSWERSCu(s) + 4HNO3 -> Cu(NO3)2(aq) +
2NO2(g) + 2H2O(l)
- Fizzing, gas was brown and needed to escape in fume hood through swirling until
solution was bright blue.
- Redox: Cu -> Cu2+
- Excess HNO3 used because we don't want it to be limiting reactant.
WITH CORRECT QUESTIONS AND
ANSWERS 2025
- Fire extinguishers (type ABC) - CORRECT-ANSWERSIn hall outside chem lab. Use for
class A (normal combustible material), B (gas, grease, oil), or C (electrical) fires.
- PASS: pull pin, aim low, squeeze handle, sweep slowly.
- Most dangerous thing in the laboratory - CORRECT-ANSWERSChemical vapours - can
be toxic, flammable, both.
- Proper way to combine water and acid - CORRECT-ANSWERSPour acid into water, not
other way around!
- Accuracy of a beaker - CORRECT-ANSWERS+-10%
- Accuracy of an Erlenmeyer - CORRECT-ANSWERS+-5%
- Accuracy of a graduated cylinder - CORRECT-ANSWERS1 decimal place?
- Accuracy of a volumetric pipette - CORRECT-ANSWERSDepends on what size, it's +- a
certain amount of mLs. 10mL = +-0.01ml.
- They are most accurate because of the small meniscus created by the narrow shape,
leading to less error.
- Accuracy of a volumetric flask - CORRECT-ANSWERS2 decimal places
- Accuracy of a top loading balance - CORRECT-ANSWERS2 decimal places
- Accuracy of an analytical balance - CORRECT-ANSWERS4 decimal places. Objects
need to be the same temp as the balance (otherwise it will form convection currents and
appear lighter) and all doors must be shut!
, - Quantitative transfer - CORRECT-ANSWERSSolid, 1 piece -> forceps, prevents
contamination
- Solid, powder -> use weighing boat/paper, tare and then add powder. Tip powder into
receptacle, tap, and rinse with some solvent to ensure everything is transferred. Or, put
the clean dry beaker on the scale and tare.
- Liquid -> Pour into receiving vessel, then rinse dispensing vessel (and any transfer
equipment, like a funnel) 3 times with solvent and add that to receiving vessel as well.
- Vacuum filtration - CORRECT-ANSWERSMake sure no cracks/chips, place rubber
stopper and Buchner funnel, wet the filter paper that is added to Buchner funnel to create
a seal. Never fill Buchner funnel more than 2/3.
- Most common natural sources of copper - CORRECT-ANSWERSChalcopyrite,
chalconite, and bornite. Must be purified from these ores.
- % yield - CORRECT-ANSWERSactual yield/theoretical yield x 100
- Only considers how much desired product is obtained, ignores side products.
- First reaction in copper lab - CORRECT-ANSWERSCu(s) + 4HNO3 -> Cu(NO3)2(aq) +
2NO2(g) + 2H2O(l)
- Fizzing, gas was brown and needed to escape in fume hood through swirling until
solution was bright blue.
- Redox: Cu -> Cu2+
- Excess HNO3 used because we don't want it to be limiting reactant.
