,Portage Learning CHEM 103 General
Chemistry I Module 5 Lab Exam
Question 1
In an experiment monitoring gas behavior via a syringe, what primary device is directly
utilized to measure the change in gas volume?
A) Analytical balance
B) Graduated syringe barrel markings
C) Barometer
D) Thiele tube [1]
Correct Answer: B) Graduated syringe barrel markings
Rationale: Gas volume changes in basic law verification labs are observed and read
directly from the graduation markings etched into the plastic or glass syringe barrel. [1,
2]
Question 2
According to Boyle’s Law, if the volume of a trapped gas sample decreases at a
constant temperature, the pressure of the gas will:
A) Decrease proportionally
B) Remain completely unchanged
C) Increase proportionally
D) Drop to zero atmospheres [1]
Correct Answer: C) Increase proportionally
Rationale: Boyle's Law outlines an inverse mathematical relationship between the
pressure and volume of a confined gas (\(P \propto \frac{1}{V}\)) when temperature and
moles are held constant. Decreasing volume causes more frequent molecular collisions
per unit area, increasing pressure. [1, 2, 3]
Question 3
A sample of gas occupies a volume of 10.5 L when the pressure is 14.3 psi. Using
Boyle's Law, what is the new volume (L) if the pressure is decreased to 12.8 psi?
A) 9.40 L
B) 11.7 L
, C) 13.2 L
D) 8.55 L [1, 2]
Correct Answer: B) 11.7 L
Rationale: Using Boyle's Law formula: \(P_1V_1 = P_2V_2 \implies (14.3 \text{
psi})(10.5 \text{ L}) = (12.8 \text{ psi})(V_2)\). Solving for \(V_{2}\) gives
\(\frac{150.15}{12.8} \approx 11.73 \text{ L}\), which rounds to 11.7 L based on three
significant figures. [1, 2]
Question 4
Which unit of pressure is most commonly read directly from a mechanical gauge
attached to a gas syringe apparatus in an introductory general chemistry lab?
A) Pascal (Pa)
B) Pounds per square inch (psi)
C) Atmosphere (atm)
D) Torr
Correct Answer: B) Pounds per square inch (psi)
Rationale: Many standard laboratory pressure transducers and mechanical gauges
designed for academic syringes are calibrated to display pressure in pounds per square
inch (psi). [1, 2]
Question 5
What physical observation occurs to a syringe plunger when a flask containing trapped
gas is shifted from a cold ice bath into a beaker of boiling water?
A) The plunger moves inward due to gas contraction.
) The plunger moves outward/upward due to gas expansion.
C) The plunger remains completely frozen in place.
D) The plunger vibrates but does not shift net position. [1]
Correct Answer: B) The plunger moves outward/upward due to gas expansion.
Rationale: Heating a gas causes the kinetic energy of its molecules to rise. According to
Charles's Law, as temperature increases, volume must increase proportionally to
preserve a constant internal pressure, pushing the plunger outward. [1]
Chemistry I Module 5 Lab Exam
Question 1
In an experiment monitoring gas behavior via a syringe, what primary device is directly
utilized to measure the change in gas volume?
A) Analytical balance
B) Graduated syringe barrel markings
C) Barometer
D) Thiele tube [1]
Correct Answer: B) Graduated syringe barrel markings
Rationale: Gas volume changes in basic law verification labs are observed and read
directly from the graduation markings etched into the plastic or glass syringe barrel. [1,
2]
Question 2
According to Boyle’s Law, if the volume of a trapped gas sample decreases at a
constant temperature, the pressure of the gas will:
A) Decrease proportionally
B) Remain completely unchanged
C) Increase proportionally
D) Drop to zero atmospheres [1]
Correct Answer: C) Increase proportionally
Rationale: Boyle's Law outlines an inverse mathematical relationship between the
pressure and volume of a confined gas (\(P \propto \frac{1}{V}\)) when temperature and
moles are held constant. Decreasing volume causes more frequent molecular collisions
per unit area, increasing pressure. [1, 2, 3]
Question 3
A sample of gas occupies a volume of 10.5 L when the pressure is 14.3 psi. Using
Boyle's Law, what is the new volume (L) if the pressure is decreased to 12.8 psi?
A) 9.40 L
B) 11.7 L
, C) 13.2 L
D) 8.55 L [1, 2]
Correct Answer: B) 11.7 L
Rationale: Using Boyle's Law formula: \(P_1V_1 = P_2V_2 \implies (14.3 \text{
psi})(10.5 \text{ L}) = (12.8 \text{ psi})(V_2)\). Solving for \(V_{2}\) gives
\(\frac{150.15}{12.8} \approx 11.73 \text{ L}\), which rounds to 11.7 L based on three
significant figures. [1, 2]
Question 4
Which unit of pressure is most commonly read directly from a mechanical gauge
attached to a gas syringe apparatus in an introductory general chemistry lab?
A) Pascal (Pa)
B) Pounds per square inch (psi)
C) Atmosphere (atm)
D) Torr
Correct Answer: B) Pounds per square inch (psi)
Rationale: Many standard laboratory pressure transducers and mechanical gauges
designed for academic syringes are calibrated to display pressure in pounds per square
inch (psi). [1, 2]
Question 5
What physical observation occurs to a syringe plunger when a flask containing trapped
gas is shifted from a cold ice bath into a beaker of boiling water?
A) The plunger moves inward due to gas contraction.
) The plunger moves outward/upward due to gas expansion.
C) The plunger remains completely frozen in place.
D) The plunger vibrates but does not shift net position. [1]
Correct Answer: B) The plunger moves outward/upward due to gas expansion.
Rationale: Heating a gas causes the kinetic energy of its molecules to rise. According to
Charles's Law, as temperature increases, volume must increase proportionally to
preserve a constant internal pressure, pushing the plunger outward. [1]
