CHEM 101L UNC Final Exam
When should you not wear gloves in the laboratory setting? - Correct answer-when
entering data into your ELN on your laptop; when writing notes on scratch paper using a
pen and paper
You make a solution of 0.1 M NaOH and accidentally spill the solution, covering your
gloved hand and onto your arm. Your wrist was exposed, and the solution came into
direct contact with your skin. What should you do? - Correct answer-tell the TA and
rinse your skin for 15 minutes
you are taking an evening laboratory session and want to bring a snack to make it
through the evening. When should you be allowed to have food at the bench top in the
lab? - Correct answer-never
accuracy - Correct answer-how close a measurement is to the true value
precision - Correct answer-a measure of how close a series of measurements are to
one another
systematic error - Correct answer-arises from a flaw in the equipment or experimental
design; can be detected and corrected; affects accuracy
example of systematic error - Correct answer-incorrectly calibrated instrument;
consistently misreads it
random error - Correct answer-arises from uncontrolled, and often uncontrollable,
variables in an experiment which has equal chance of being positive or negative; cannot
be detected or corrected for; affects precision
example of random error - Correct answer-Human error and lack of instrument
sensitivity
why does ice float on water? - Correct answer-ice is less dense than liquid h2o
how does temperature affect the density of a solution? - Correct answer-as temperature
increases, density decreases
does calibration using standards help improve the accuracy or precision of the
experiment? - Correct answer-accuracy
What axis is the independent variable on? - Correct answer-x-axis
, what axis is the dependent variable on? - Correct answer-y-axis
weighing by difference - Correct answer-substance mass = mass of container with
substance - mass of container without substance
mean - Correct answer-The sum of a set of numbers divided by the number of elements
in the set
standard deviation - Correct answer-the square root of the sum of the average
subtracted from each measurement divided by the number of measurements
CV - Correct answer-the standard deviation divided by the mean
kilo - Correct answer-10^3
centi - Correct answer-10^-2
milli - Correct answer-10^-3
micro - Correct answer-10^-6
nano - Correct answer-10^-9
pico - Correct answer-10^-12
density - Correct answer-mass/volume
system - Correct answer-consists of the molecules that are reacting
surroundings - Correct answer-everything outside the system
exothermic - Correct answer-the system releases energy/heat to its surroundings;
negative DH
endothermic - Correct answer-the systems absorbs heat form the surroundings; positive
DH
bond formation - Correct answer-releases energy; exothermic; electrons transition to
lower energy states; stable
breaking a bond - Correct answer-absorbs energy; endothermic; electrons transition to
higher energy states; unstable
in the laboratory should you add acid to water or water to acid? - Correct answer-add
acid to water
When should you not wear gloves in the laboratory setting? - Correct answer-when
entering data into your ELN on your laptop; when writing notes on scratch paper using a
pen and paper
You make a solution of 0.1 M NaOH and accidentally spill the solution, covering your
gloved hand and onto your arm. Your wrist was exposed, and the solution came into
direct contact with your skin. What should you do? - Correct answer-tell the TA and
rinse your skin for 15 minutes
you are taking an evening laboratory session and want to bring a snack to make it
through the evening. When should you be allowed to have food at the bench top in the
lab? - Correct answer-never
accuracy - Correct answer-how close a measurement is to the true value
precision - Correct answer-a measure of how close a series of measurements are to
one another
systematic error - Correct answer-arises from a flaw in the equipment or experimental
design; can be detected and corrected; affects accuracy
example of systematic error - Correct answer-incorrectly calibrated instrument;
consistently misreads it
random error - Correct answer-arises from uncontrolled, and often uncontrollable,
variables in an experiment which has equal chance of being positive or negative; cannot
be detected or corrected for; affects precision
example of random error - Correct answer-Human error and lack of instrument
sensitivity
why does ice float on water? - Correct answer-ice is less dense than liquid h2o
how does temperature affect the density of a solution? - Correct answer-as temperature
increases, density decreases
does calibration using standards help improve the accuracy or precision of the
experiment? - Correct answer-accuracy
What axis is the independent variable on? - Correct answer-x-axis
, what axis is the dependent variable on? - Correct answer-y-axis
weighing by difference - Correct answer-substance mass = mass of container with
substance - mass of container without substance
mean - Correct answer-The sum of a set of numbers divided by the number of elements
in the set
standard deviation - Correct answer-the square root of the sum of the average
subtracted from each measurement divided by the number of measurements
CV - Correct answer-the standard deviation divided by the mean
kilo - Correct answer-10^3
centi - Correct answer-10^-2
milli - Correct answer-10^-3
micro - Correct answer-10^-6
nano - Correct answer-10^-9
pico - Correct answer-10^-12
density - Correct answer-mass/volume
system - Correct answer-consists of the molecules that are reacting
surroundings - Correct answer-everything outside the system
exothermic - Correct answer-the system releases energy/heat to its surroundings;
negative DH
endothermic - Correct answer-the systems absorbs heat form the surroundings; positive
DH
bond formation - Correct answer-releases energy; exothermic; electrons transition to
lower energy states; stable
breaking a bond - Correct answer-absorbs energy; endothermic; electrons transition to
higher energy states; unstable
in the laboratory should you add acid to water or water to acid? - Correct answer-add
acid to water
