CHEM 1LD FINAL EXAM REVIEW QUESTIONS WELL ANSWERED LATEST UPDATE 2026
What is the use of a volumetric flask? - Answers Volumetric flasks are used to make solutions of
known concentration (stock or standard solutions) by the dissolution of a known mass of solid or the
dilution of a more concentrated solution.
How many decimal places does a volumetric flask go to? - Answers Two (ex: 10.00)
What is the use of a volumetric pipette? - Answers A volumetric pipet is used "to deliver" a single,
fixed volume of liquid at a specific temperature (usually 20.0°C).
Why do we pre-rinse a volumetric pipette? - Answers To remove any impurities from the inside walls.
Why should you never use a vol. pipette to transfer heated solutions or undissolved solids? - Answers
The heat will distort the calibrated volume and solids can "condense out" on the colder glass walls of
the pipet, clogging the narrow stem and tip.
What are the two different types of Mohr pipettes? - Answers Graduated tip and clear tip.
What is the use of Mohr pipettes? - Answers Allows for the transfer of liquids of variable volumes.
How is a concave (downward curving) meniscus read? - Answers Read at the bottom of the meniscus
(ex: water).
How is a convex (upward curving) meniscus read? - Answers Read from the top of the meniscus (ex:
mercury).
Why should you never dry volumetric pipettes or Mohr pipettes in an oven? - Answers The heat will
distort the glass and change the calibrated volumes.
Precision refers to: - Answers The reproducibility of a measurement.
Accuracy is a measure of: - Answers Of the closeness to true value.
What is a random (indeterminate) error? - Answers Caused by uncontrollable fluctuations in variables
that affect experimental results. For example, air fluctuations occurring as students open and close
lab doors cause changes in pressure readings.
What is a systematic error? - Answers Instrumental, methodological, or personal mistakes causing
"lopsided" data, which is consistently deviated in one direction from the true value. Examples of
systematic errors: an instrumental error results when a spectrometer drifts away from calibrated
settings; a methodological error is created by using the wrong indicator for an acid-base titration; and,
a personal error occurs when an experimenter records only even numbers for the last digit of buret
volumes.
What is a gross error? - Answers Caused by experimenter carelessness or equipment failure. These
"outliers" are so far above or below the true value that they are usually discarded when assessing
data.
Deviation from the mean: - Answers The difference between the individual experimental value and
the mean value.
Average deviation: - Answers Used when a data set contains less than 5 repetitive measurements. A
small average deviation indicates data points clustered closely around the mean and good precision.
Relative Average Deviation: - Answers The average deviation divided by the average and then
expressed as a percentage.
The number of degrees of Freedom (N-1) - Answers The total number of measurements minus one.
Percent Error: - Answers [(Experimental-Theoretical)/Theoretical]x100
Q Test: - Answers Absolute difference between the questioned measurement (xq) and the next
closest measurement (xn) divided by the spread (ω), the difference between the largest and smallest
measurement, of the entire set of data.
Confidence Levels: - Answers The percent probability a measurement will fall into a range around the
mean (x).
Filtration: - Answers The technique used to separate solids from liquids, is the act of pouring a
mixture onto a membrane (filter paper) that allows the passage of liquid (the filtrate) and results in
the collection of the solid.
What are the two main types of filtration: - Answers Gravity and Vacuum Filtration
Gravity Filtration: - Answers Utilizes the technique of pouring a solution over filter paper in a funnel,
while gravity drives the liquid down the funnel into a beaker or flask, making for the separation of
solid and liquid.
Vaccuum Filtration: - Answers Utilizes the technique of pouring a solution over filter paper in a
buchner funnel while vaccuum suction separates solid and liquid.
, Aspirator Pumps: - Answers A vacuum aspirator creates the suction that pulls liquid through the filter
and filter paper using a pump submerged in a water bucket. When the water aspirator is turned on
the flow of water creates suction.
Balancing Redox Reactions - Answers 1.Write separate eqns for oxidation & reduction half-rxns. Only
write down atoms involved in half-rxn.
2. For each half rxn,
Balance all elements except H & O
Balance O w/ H2O
Balance H w/ H+
Balance charge w/ e-
3. If necessary, multiply one or both balanced half-rxns by an integer so that the # e- xfer'd is equal in
two half-rxns.
4. Add half-rxns & cancel identical species.
5. If acidic soln, go to #8. If basic soln, go to #6.
6. Add same # −OH ions as H+ ions to both sides of eqn.
7. Form H2O on side w/ both -OH & H+, eliminate H2O's that appear on both sides.
8. Check that elements & charge balance.
What is a desiccator? - Answers A glass bowl and lid each with thick glass rims that permit a seal
when greased. Desiccant (a hygroscopic chemical that absorbs water out of the air) is placed beneath
the perforated ceramic disk. A sample in a beaker or crucible is placed on the top of this disk.
What is the use of a desiccator? - Answers To either dry a chemical or keep a chemical from
becoming "wet" from atmospheric humidity (water in the air).
What is crystallization? - Answers A common technique used to purify solids. Two common methods
of crystallization are "gradual cooling" and "diffusion".
What is gradual cooling? - Answers Involves dissolving the impure solid in a minimum amount of a
hot solvent and allowing the resulting solution to cool slowly to room temperature. During the cooling
process, pure (or almost pure) crystals form and are then collected by vacuum filtration.
What is the use of a buret? - Answers Used to deliver variable liquid amounts for titrations.
How do you read a buret? - Answers The volume delivered is determined by subtracting the initial
volume from the final volume (Vf - Vi). Read to the hundredths place.
What is the Median Odor Threshold? - Answers When 50% of the population can smell the chemical.
When is a chemical considered dangerous? - Answers When the median odor threshold is above the
PEL (permissible exposure limit).
How does a fume hood work? - Answers It pulls air away from the user and out of the room to an
exhaust fan on the roof.
What should the air flow be when the fume hood is in use? - Answers 100 ft/min.
How far into the fume hood should chemicals and glassware be placed? - Answers At least 6 inches.
What happens to the vapors when the sash is fully closed? - Answers The vapor exit the beaker, drop
to the bottom of the beaker, and proceed towards the back of the fume hood.
What is a hazard? - Answers Potential source of harm.
What is exposure? - Answers Contact with hazard in a way that can cause harm.
What is the Extent of Harm? - Answers Function of dose, duration of exposure, and route of
exposure.
Toxicity: - Answers Ability of a toxicant to damage an organ or disrupt a biological process.
Acute Toxicity: - Answers Ability of Toxicant to damage with a single dose (ex: CO, CN-)
Chronic Toxicity: - Answers Ability of a toxicant to damage with multiple small doses (Ex: Pb, As).
What are the four chemical symbols that represent Toxins? - Answers Skull and crossbones
(extremely toxic poison), the head with the white star (target organ toxicity), the exclamation mark
(acute toxicity) and the dead tree and fish (aquatic toxicity).
What are flammables? - Answers Chemicals that ignite and burn easily and release a lot of heat.
What is the use of a volumetric flask? - Answers Volumetric flasks are used to make solutions of
known concentration (stock or standard solutions) by the dissolution of a known mass of solid or the
dilution of a more concentrated solution.
How many decimal places does a volumetric flask go to? - Answers Two (ex: 10.00)
What is the use of a volumetric pipette? - Answers A volumetric pipet is used "to deliver" a single,
fixed volume of liquid at a specific temperature (usually 20.0°C).
Why do we pre-rinse a volumetric pipette? - Answers To remove any impurities from the inside walls.
Why should you never use a vol. pipette to transfer heated solutions or undissolved solids? - Answers
The heat will distort the calibrated volume and solids can "condense out" on the colder glass walls of
the pipet, clogging the narrow stem and tip.
What are the two different types of Mohr pipettes? - Answers Graduated tip and clear tip.
What is the use of Mohr pipettes? - Answers Allows for the transfer of liquids of variable volumes.
How is a concave (downward curving) meniscus read? - Answers Read at the bottom of the meniscus
(ex: water).
How is a convex (upward curving) meniscus read? - Answers Read from the top of the meniscus (ex:
mercury).
Why should you never dry volumetric pipettes or Mohr pipettes in an oven? - Answers The heat will
distort the glass and change the calibrated volumes.
Precision refers to: - Answers The reproducibility of a measurement.
Accuracy is a measure of: - Answers Of the closeness to true value.
What is a random (indeterminate) error? - Answers Caused by uncontrollable fluctuations in variables
that affect experimental results. For example, air fluctuations occurring as students open and close
lab doors cause changes in pressure readings.
What is a systematic error? - Answers Instrumental, methodological, or personal mistakes causing
"lopsided" data, which is consistently deviated in one direction from the true value. Examples of
systematic errors: an instrumental error results when a spectrometer drifts away from calibrated
settings; a methodological error is created by using the wrong indicator for an acid-base titration; and,
a personal error occurs when an experimenter records only even numbers for the last digit of buret
volumes.
What is a gross error? - Answers Caused by experimenter carelessness or equipment failure. These
"outliers" are so far above or below the true value that they are usually discarded when assessing
data.
Deviation from the mean: - Answers The difference between the individual experimental value and
the mean value.
Average deviation: - Answers Used when a data set contains less than 5 repetitive measurements. A
small average deviation indicates data points clustered closely around the mean and good precision.
Relative Average Deviation: - Answers The average deviation divided by the average and then
expressed as a percentage.
The number of degrees of Freedom (N-1) - Answers The total number of measurements minus one.
Percent Error: - Answers [(Experimental-Theoretical)/Theoretical]x100
Q Test: - Answers Absolute difference between the questioned measurement (xq) and the next
closest measurement (xn) divided by the spread (ω), the difference between the largest and smallest
measurement, of the entire set of data.
Confidence Levels: - Answers The percent probability a measurement will fall into a range around the
mean (x).
Filtration: - Answers The technique used to separate solids from liquids, is the act of pouring a
mixture onto a membrane (filter paper) that allows the passage of liquid (the filtrate) and results in
the collection of the solid.
What are the two main types of filtration: - Answers Gravity and Vacuum Filtration
Gravity Filtration: - Answers Utilizes the technique of pouring a solution over filter paper in a funnel,
while gravity drives the liquid down the funnel into a beaker or flask, making for the separation of
solid and liquid.
Vaccuum Filtration: - Answers Utilizes the technique of pouring a solution over filter paper in a
buchner funnel while vaccuum suction separates solid and liquid.
, Aspirator Pumps: - Answers A vacuum aspirator creates the suction that pulls liquid through the filter
and filter paper using a pump submerged in a water bucket. When the water aspirator is turned on
the flow of water creates suction.
Balancing Redox Reactions - Answers 1.Write separate eqns for oxidation & reduction half-rxns. Only
write down atoms involved in half-rxn.
2. For each half rxn,
Balance all elements except H & O
Balance O w/ H2O
Balance H w/ H+
Balance charge w/ e-
3. If necessary, multiply one or both balanced half-rxns by an integer so that the # e- xfer'd is equal in
two half-rxns.
4. Add half-rxns & cancel identical species.
5. If acidic soln, go to #8. If basic soln, go to #6.
6. Add same # −OH ions as H+ ions to both sides of eqn.
7. Form H2O on side w/ both -OH & H+, eliminate H2O's that appear on both sides.
8. Check that elements & charge balance.
What is a desiccator? - Answers A glass bowl and lid each with thick glass rims that permit a seal
when greased. Desiccant (a hygroscopic chemical that absorbs water out of the air) is placed beneath
the perforated ceramic disk. A sample in a beaker or crucible is placed on the top of this disk.
What is the use of a desiccator? - Answers To either dry a chemical or keep a chemical from
becoming "wet" from atmospheric humidity (water in the air).
What is crystallization? - Answers A common technique used to purify solids. Two common methods
of crystallization are "gradual cooling" and "diffusion".
What is gradual cooling? - Answers Involves dissolving the impure solid in a minimum amount of a
hot solvent and allowing the resulting solution to cool slowly to room temperature. During the cooling
process, pure (or almost pure) crystals form and are then collected by vacuum filtration.
What is the use of a buret? - Answers Used to deliver variable liquid amounts for titrations.
How do you read a buret? - Answers The volume delivered is determined by subtracting the initial
volume from the final volume (Vf - Vi). Read to the hundredths place.
What is the Median Odor Threshold? - Answers When 50% of the population can smell the chemical.
When is a chemical considered dangerous? - Answers When the median odor threshold is above the
PEL (permissible exposure limit).
How does a fume hood work? - Answers It pulls air away from the user and out of the room to an
exhaust fan on the roof.
What should the air flow be when the fume hood is in use? - Answers 100 ft/min.
How far into the fume hood should chemicals and glassware be placed? - Answers At least 6 inches.
What happens to the vapors when the sash is fully closed? - Answers The vapor exit the beaker, drop
to the bottom of the beaker, and proceed towards the back of the fume hood.
What is a hazard? - Answers Potential source of harm.
What is exposure? - Answers Contact with hazard in a way that can cause harm.
What is the Extent of Harm? - Answers Function of dose, duration of exposure, and route of
exposure.
Toxicity: - Answers Ability of a toxicant to damage an organ or disrupt a biological process.
Acute Toxicity: - Answers Ability of Toxicant to damage with a single dose (ex: CO, CN-)
Chronic Toxicity: - Answers Ability of a toxicant to damage with multiple small doses (Ex: Pb, As).
What are the four chemical symbols that represent Toxins? - Answers Skull and crossbones
(extremely toxic poison), the head with the white star (target organ toxicity), the exclamation mark
(acute toxicity) and the dead tree and fish (aquatic toxicity).
What are flammables? - Answers Chemicals that ignite and burn easily and release a lot of heat.
