Chemistry 1LD Practical: Safety Questions With Complete
Solutions
A mixture of acetone and heptane is used in this project to create
the
TLC eluent. Only a small amount of liquid (2-3mL) is needed
for the development chamber, so the volume to volume ratios of
heptane to acetone must be converted the reasonable quantities
so that excess waste is not created. If the total volume is 2 to 3
mL, fill in the table to to show how much of each chemical is
needed to make the ratio.
Ratio: 1:1, 1:2, 2:1, 3:2
order: H volume; Acetone volume
The ratio between the solvents should be reasonably precise, but
not as precise as when making standard solutions for a Beer's
Law plot.
What is best piece of glassware to measure out the above
volumes? Correct Answers 1, 1
1, 2
2, 1
1.5, 1
graduated cylinder
A solution is created when a small amount of
[ Select ]
* dissolves in a large amount of
[ Select )
수.
When a solution's concentration is reported in moles of [ Select ]
,- per liter of solution, the concentration is
reported as a [ Select ]
When a solution's concentration is reported in moles of [ Select]
* per [Select)
of solvent,
the concentration is reported as a Correct Answers solute
solvent
solute
molarity
solute
kilograms
molality
A student combined the following and stirred the solution for 10
minutes:
1.031 g of vanillin
2.20 mL 0.010 M acetic acid
9.0 mg horseradish peroxidase
7.5 mL of 3% H202
The precipitate which formed was collected by vacuum filtration
and dried in the oven. Once the solid reached room temperature
it is
massed.
Answers should have the correct number of significant figures
and no units (omit "g" or "%" from the answers).
What is the theoretical yield (in grams)
of vanillic acid?
of divanillin?
If 0.856 g of product is collected, what is the percent yield
of vanillic acid?
of divanillin?
,If the mass of the product is 1.374 g, the product is still
and needs to be returned to the Correct Answers 1.139
1.024
75.1
83.6
wet
oven
A student dissolved a product in acetone and spotted on a silica
TLC plate to determine the purity of the product. A 2:1 mixture
of heptane:acetone was placed in the developing chamber. In
this setup, silica is the [ Select ] phase and the heptane/acetone
mixture is the [ Select ] phase or the [ Select ]. Correct Answers
stationary
mobile
eluent
A student ran a TLC of a mixture of two unknown compounds,
A and B.
Calculate the Rf values for the components of the mixture.
Round each answer to one significant figure.
Spot A at 4, Spot B at 2.5, Solvent line at 7
Which compound is more polar?
Which compound is the most attracted to the eluent? Correct
Answers 0.6
0.4
B
A
, An aqueous solution was created by placing 0.018 g of NaCl
into a 50 mL volumetric flask and diluting to volume with
deionized water.
(Because the amount of solute is small, you may assume that the
volume & density of the solution is equal to the volume &
density of the solvent where appropriate.)
Find the concentration in terms of the following units. Report
your answers without scientific notation.
Only input numbers. Your answers must be expressed to the
correct number of significant figures. Any values less than one
must have a zero in front of the decimal (e.g. 0.01 not .01)
Molarity:
Molality:
Mole fraction of NaCl:
Mass % of NaCl Correct Answers 0.0062
0.0062
0.00011
0.036
Argument Driven Inquiry (ADI) is or requires which of the
following?
active listening and participation
social interaction to construct knowledge
messiness
metacognition
a teaching assistant acting as a facilitator
curiosity
a right answer
systematic evaluation of different ideas Correct Answers active
listening and participation
Solutions
A mixture of acetone and heptane is used in this project to create
the
TLC eluent. Only a small amount of liquid (2-3mL) is needed
for the development chamber, so the volume to volume ratios of
heptane to acetone must be converted the reasonable quantities
so that excess waste is not created. If the total volume is 2 to 3
mL, fill in the table to to show how much of each chemical is
needed to make the ratio.
Ratio: 1:1, 1:2, 2:1, 3:2
order: H volume; Acetone volume
The ratio between the solvents should be reasonably precise, but
not as precise as when making standard solutions for a Beer's
Law plot.
What is best piece of glassware to measure out the above
volumes? Correct Answers 1, 1
1, 2
2, 1
1.5, 1
graduated cylinder
A solution is created when a small amount of
[ Select ]
* dissolves in a large amount of
[ Select )
수.
When a solution's concentration is reported in moles of [ Select ]
,- per liter of solution, the concentration is
reported as a [ Select ]
When a solution's concentration is reported in moles of [ Select]
* per [Select)
of solvent,
the concentration is reported as a Correct Answers solute
solvent
solute
molarity
solute
kilograms
molality
A student combined the following and stirred the solution for 10
minutes:
1.031 g of vanillin
2.20 mL 0.010 M acetic acid
9.0 mg horseradish peroxidase
7.5 mL of 3% H202
The precipitate which formed was collected by vacuum filtration
and dried in the oven. Once the solid reached room temperature
it is
massed.
Answers should have the correct number of significant figures
and no units (omit "g" or "%" from the answers).
What is the theoretical yield (in grams)
of vanillic acid?
of divanillin?
If 0.856 g of product is collected, what is the percent yield
of vanillic acid?
of divanillin?
,If the mass of the product is 1.374 g, the product is still
and needs to be returned to the Correct Answers 1.139
1.024
75.1
83.6
wet
oven
A student dissolved a product in acetone and spotted on a silica
TLC plate to determine the purity of the product. A 2:1 mixture
of heptane:acetone was placed in the developing chamber. In
this setup, silica is the [ Select ] phase and the heptane/acetone
mixture is the [ Select ] phase or the [ Select ]. Correct Answers
stationary
mobile
eluent
A student ran a TLC of a mixture of two unknown compounds,
A and B.
Calculate the Rf values for the components of the mixture.
Round each answer to one significant figure.
Spot A at 4, Spot B at 2.5, Solvent line at 7
Which compound is more polar?
Which compound is the most attracted to the eluent? Correct
Answers 0.6
0.4
B
A
, An aqueous solution was created by placing 0.018 g of NaCl
into a 50 mL volumetric flask and diluting to volume with
deionized water.
(Because the amount of solute is small, you may assume that the
volume & density of the solution is equal to the volume &
density of the solvent where appropriate.)
Find the concentration in terms of the following units. Report
your answers without scientific notation.
Only input numbers. Your answers must be expressed to the
correct number of significant figures. Any values less than one
must have a zero in front of the decimal (e.g. 0.01 not .01)
Molarity:
Molality:
Mole fraction of NaCl:
Mass % of NaCl Correct Answers 0.0062
0.0062
0.00011
0.036
Argument Driven Inquiry (ADI) is or requires which of the
following?
active listening and participation
social interaction to construct knowledge
messiness
metacognition
a teaching assistant acting as a facilitator
curiosity
a right answer
systematic evaluation of different ideas Correct Answers active
listening and participation
