CHEM 122 LAB UNR EXAM QUESTIONS AND
ANSWERS 100% CORRECT
At the freezing point, the liquid form of a substance _______________________ the solid form of
the substance. - ANSWER is in equilibrium with
equation to calculate the difference from the normal freezing point is - ANSWER ΔTf=iKfm
Suppose that you add 27.8 g of an unknown molecular compound to 0.250 kg of benzene,
which has a
KfKf
of 5.12oC/m. With the added solute, you find that there is a freezing point depression of
3.98oC compared to pure benzene.
What is the molar mass (in g/mol) of the unknown compound? - ANSWER 143
What is the freezing point (in degrees Celcius) of 4.15 kg of water if it contains 181.8 g of
butanol, C4H9OH?
The freezing point depression constant for water is 1.86 oC/m and the molar mass of butanol
is 74.12 g/mol. - ANSWER -1.1
, Students are investigating a solvent for use in freezing point depression experiments. They
measured the freezing point of the solvent as −12.6 ⁰C. The solution they made by dissolving
0.484 g of ethanol (46.07 g/mol) in 8.254 g of the solvent has a freezing point of -18.3 ⁰C.
Determine the freezing point depression constant, Kf, for the solvent. - ANSWER 4.5
Ethyl propanoate is an organic molecule that smells like pineapple and has a molar mass of
102.132 g/mol. It is soluble in the organic solvent acetone.
What is the molality of a solution prepared with 89.1 g of ethyl propanoate and 504.2 mL of
acetone? The density of acetone is 0.784 g/mL. - ANSWER 2.21
When the required amount of one solution has been added to the second solution to
complete the reaction - ANSWER equivalence point
Process of slowly adding a solution to react with another solution and determine the
concentration of one of the solutions based on the reaction between them - ANSWER
Titration
Glassware that allows a solution to be precisely and slowly added to another solution -
ANSWER Burette
A reagent added to the analyte solution that changes color when the reaction is complete -
ANSWER Indicator
Solution of known concentration that is slowly added to a solution of unknown concentration
ANSWERS 100% CORRECT
At the freezing point, the liquid form of a substance _______________________ the solid form of
the substance. - ANSWER is in equilibrium with
equation to calculate the difference from the normal freezing point is - ANSWER ΔTf=iKfm
Suppose that you add 27.8 g of an unknown molecular compound to 0.250 kg of benzene,
which has a
KfKf
of 5.12oC/m. With the added solute, you find that there is a freezing point depression of
3.98oC compared to pure benzene.
What is the molar mass (in g/mol) of the unknown compound? - ANSWER 143
What is the freezing point (in degrees Celcius) of 4.15 kg of water if it contains 181.8 g of
butanol, C4H9OH?
The freezing point depression constant for water is 1.86 oC/m and the molar mass of butanol
is 74.12 g/mol. - ANSWER -1.1
, Students are investigating a solvent for use in freezing point depression experiments. They
measured the freezing point of the solvent as −12.6 ⁰C. The solution they made by dissolving
0.484 g of ethanol (46.07 g/mol) in 8.254 g of the solvent has a freezing point of -18.3 ⁰C.
Determine the freezing point depression constant, Kf, for the solvent. - ANSWER 4.5
Ethyl propanoate is an organic molecule that smells like pineapple and has a molar mass of
102.132 g/mol. It is soluble in the organic solvent acetone.
What is the molality of a solution prepared with 89.1 g of ethyl propanoate and 504.2 mL of
acetone? The density of acetone is 0.784 g/mL. - ANSWER 2.21
When the required amount of one solution has been added to the second solution to
complete the reaction - ANSWER equivalence point
Process of slowly adding a solution to react with another solution and determine the
concentration of one of the solutions based on the reaction between them - ANSWER
Titration
Glassware that allows a solution to be precisely and slowly added to another solution -
ANSWER Burette
A reagent added to the analyte solution that changes color when the reaction is complete -
ANSWER Indicator
Solution of known concentration that is slowly added to a solution of unknown concentration
