Chem 1B Lab Exam Questions With Complete Solutions
. Freezing point of a pure solvent Correct Answers Solvent:
lauric acid (kf = 3.9 ℃/m)
Tf: constant
. Freezing point of a solution Correct Answers Solvent: lauric
acid
Solute: unknown
When the solution starts to freeze, the temperature will decrease
with another constant speed.
•Iodine clock reaction Correct Answers a classical chemical
clock reaction to display chemical kinetics in action. It involves
various iodine species (I-, I2, or IO3-) and redox reagents in the
presence of starch.
△T Correct Answers change in temperature, Tfinal - Tinitial
(℃)
△Tf=Kf·m Correct Answers △Tf: the change of freezing
point
Kf: freezing point constant of a given solvent
m: molality of solute
Activation energy(Ea) Correct Answers •the minimum energy
that must be provided to compounds to result in a chemical
reaction. Activation energy can be thought of as the magnitude
, of the potential barrier separating minima of the potential energy
surface pertaining to the initial and final state.
•Unit: J/mol or kJ/mol
Alkaline Earths (Group 2) Correct Answers Be, Mg, Ca, Sr,
Ba, and Ra.
Alloy Correct Answers a mixture of metals, or a metal
combined with one or more other elements. (e.g. Al-Zn alloy)
An 80.78-g sample of copper metal at 99.1 °C is placed in a
calorimeter containing 200.00 g of water at 22.0 °C. The
contents of the calorimeter reach a maximum temperature of
24.8 °C. Assume no heat is absorbed or lost by the calorimeter
itself. cp(water) = 4.18 J/(g ⋅ °C).
This process ____________________. Check all that apply.
A.
results in a positive value of q for the metal.
B.
is exothermic.
C.
results in a negative value of q for the metal.
D.
is a chemical reaction.
E.
is endothermic. Correct Answers B.
is exothermic.
C.
results in a negative value of q for the metal.
. Freezing point of a pure solvent Correct Answers Solvent:
lauric acid (kf = 3.9 ℃/m)
Tf: constant
. Freezing point of a solution Correct Answers Solvent: lauric
acid
Solute: unknown
When the solution starts to freeze, the temperature will decrease
with another constant speed.
•Iodine clock reaction Correct Answers a classical chemical
clock reaction to display chemical kinetics in action. It involves
various iodine species (I-, I2, or IO3-) and redox reagents in the
presence of starch.
△T Correct Answers change in temperature, Tfinal - Tinitial
(℃)
△Tf=Kf·m Correct Answers △Tf: the change of freezing
point
Kf: freezing point constant of a given solvent
m: molality of solute
Activation energy(Ea) Correct Answers •the minimum energy
that must be provided to compounds to result in a chemical
reaction. Activation energy can be thought of as the magnitude
, of the potential barrier separating minima of the potential energy
surface pertaining to the initial and final state.
•Unit: J/mol or kJ/mol
Alkaline Earths (Group 2) Correct Answers Be, Mg, Ca, Sr,
Ba, and Ra.
Alloy Correct Answers a mixture of metals, or a metal
combined with one or more other elements. (e.g. Al-Zn alloy)
An 80.78-g sample of copper metal at 99.1 °C is placed in a
calorimeter containing 200.00 g of water at 22.0 °C. The
contents of the calorimeter reach a maximum temperature of
24.8 °C. Assume no heat is absorbed or lost by the calorimeter
itself. cp(water) = 4.18 J/(g ⋅ °C).
This process ____________________. Check all that apply.
A.
results in a positive value of q for the metal.
B.
is exothermic.
C.
results in a negative value of q for the metal.
D.
is a chemical reaction.
E.
is endothermic. Correct Answers B.
is exothermic.
C.
results in a negative value of q for the metal.
