Chem 101L CompLete exam Questions with
answers 100% CorreCt
You are taking an evening lab session and want to bring a snack to help you make it through the evening.
When should you be allowed to have food at the bench top in the lab? ✔✔ - never
_______________ error arises from a flaw in the equipment or in the experimental design. This type of
error _______________ be detected and corrected. ✔✔ - Systematic
Can
What is a decomposition reaction? ✔✔ - When something is broken down into smaller molecules
(AB→A+B)
What is a precipitate? ✔✔ - A solid that forms from a solution during a chemical reaction.
What is the full balanced equation for the neutralization of barium hydroxide with sulfuric acid? ✔✔ -
Ba(OH)2 (aq) + H2SO4 (aq) --> Ba(SO4) (s) + 2H2O (l)
What is the purpose of the blank in Beer's law experiment? ✔✔ - solution without analyte as a measure
of background absorbance in cuvette
What volume of a 3.0 x10^-3 M solution is needed to prepare 50.0 mL of 5.0 x10 ^-5 M ; how many
moles of solute are in this solution ✔✔ - (0.003 M) (x L) = (0.00005 M) (0.050 L)
x = 0.00083 L or 0.83 mL
0.003M * 0.00083L = 2.5x10^-6 mol
Whats the purpose of a calibration curve ✔✔ - mathematical model for the concentration of a sample is
unknown but absorbance is measured
when a species gets oxidized it ✔✔ - loses electrons
, when a species gets reduced it ✔✔ - gaines electrons
When should you not wear gloves in the lab setting ✔✔ - when entering in data into your ELN on your
laptop
when writing notes on scratch paper using pen and paper
Which is the larger quantity solvent or solute ✔✔ - solvent
why do bond forming reactions release energy ✔✔ - electrons go to lower energy states and releases
energy in the form of heat or light
potential energy is lower than the separate states so its more stable and favorable
Why do we only record absorbance at a wavelength that gives the greatest absorbance value for Allura
Red (wavelength max) ✔✔ - wavelength with greatest amount of absorbed light
Why do we use two cups in a coffee cup calorimeter setup ✔✔ - to isolate the system more, to prevent
the transfer of heat to the surroundings beyond the solvent
Why do you need a stir bar in the calorimeter ✔✔ - to ensure the solute is dissolved completely so the
reaction goes to completion
Why does ice float on water? ✔✔ - Ice is less dense than water
Why is a catalyst needed in the decomposition of hydrogen peroxide into water and oxygen ✔✔ - the
reaction occurs to slowly naturally
why is enthalpy change considered a state function? how does this relate to hess's law ✔✔ - Enthalpy
change is a state function because it is not pathway dependent. It doesn't matter what steps are taken to
answers 100% CorreCt
You are taking an evening lab session and want to bring a snack to help you make it through the evening.
When should you be allowed to have food at the bench top in the lab? ✔✔ - never
_______________ error arises from a flaw in the equipment or in the experimental design. This type of
error _______________ be detected and corrected. ✔✔ - Systematic
Can
What is a decomposition reaction? ✔✔ - When something is broken down into smaller molecules
(AB→A+B)
What is a precipitate? ✔✔ - A solid that forms from a solution during a chemical reaction.
What is the full balanced equation for the neutralization of barium hydroxide with sulfuric acid? ✔✔ -
Ba(OH)2 (aq) + H2SO4 (aq) --> Ba(SO4) (s) + 2H2O (l)
What is the purpose of the blank in Beer's law experiment? ✔✔ - solution without analyte as a measure
of background absorbance in cuvette
What volume of a 3.0 x10^-3 M solution is needed to prepare 50.0 mL of 5.0 x10 ^-5 M ; how many
moles of solute are in this solution ✔✔ - (0.003 M) (x L) = (0.00005 M) (0.050 L)
x = 0.00083 L or 0.83 mL
0.003M * 0.00083L = 2.5x10^-6 mol
Whats the purpose of a calibration curve ✔✔ - mathematical model for the concentration of a sample is
unknown but absorbance is measured
when a species gets oxidized it ✔✔ - loses electrons
, when a species gets reduced it ✔✔ - gaines electrons
When should you not wear gloves in the lab setting ✔✔ - when entering in data into your ELN on your
laptop
when writing notes on scratch paper using pen and paper
Which is the larger quantity solvent or solute ✔✔ - solvent
why do bond forming reactions release energy ✔✔ - electrons go to lower energy states and releases
energy in the form of heat or light
potential energy is lower than the separate states so its more stable and favorable
Why do we only record absorbance at a wavelength that gives the greatest absorbance value for Allura
Red (wavelength max) ✔✔ - wavelength with greatest amount of absorbed light
Why do we use two cups in a coffee cup calorimeter setup ✔✔ - to isolate the system more, to prevent
the transfer of heat to the surroundings beyond the solvent
Why do you need a stir bar in the calorimeter ✔✔ - to ensure the solute is dissolved completely so the
reaction goes to completion
Why does ice float on water? ✔✔ - Ice is less dense than water
Why is a catalyst needed in the decomposition of hydrogen peroxide into water and oxygen ✔✔ - the
reaction occurs to slowly naturally
why is enthalpy change considered a state function? how does this relate to hess's law ✔✔ - Enthalpy
change is a state function because it is not pathway dependent. It doesn't matter what steps are taken to
