PASSAGE II

A chemist conducted an experiment using 3
gases: hydrogen (H2), carbon monoxide (CO), and
oxygen (O2). For each gas, the chemist performed
the following steps in order:

1. She fitted a 5 liter (L) stainless steel vessel with a
cap that included a vacuum pump, a gas inlet valve,
and an internal pressure-temperature display. (The
internal pressure-temperature display showed both
the real-time pressure and temperature inside the
vessel after the cap was fitted.)

2. She vacuumed air out of the vessel until the
internal pressure was 0.00 kilopascal (kPa).

3. She placed the vessel on a scale and calibrated
the scale to 0.00 gram (g).

4. She added a predetermined amount of H2, CO, or
O2 to the vessel.

5. When the internal temperature of the vessel
reached equilibrium at 23 degrees Celsius (°C), she
recorded the mass of the gas inside the vessel and
the pressure inside the vessel.

6. Steps 1-5 were repeated several times with
different amounts of CO, H2, and O2.

Steps 1-6 were then repeated using a 10 L vessel,
instead of the 5 L vessel. All results are set forth in
Figures 1 and 2.

Figure 1

Figure 2
Suppose the chemist had repeated Steps 1-6
using a 7 L vessel. Based on Figures 1 and 2, the
pressure created inside the vessel by 500 grams
of oxygen gas would most likely have been:

A.
less than 25 kPa.
B.
between 25 and 100 kPa.
C.
between 100 and 175 kPa.
D.
greater than 175 kPa.

Based on Figure 2, the pressure created inside the vessel by 500 grams of oxygen gas in a 10 L vessel is approximately 100 kPa. Since a 7 L vessel has a smaller volume than a 10 L vessel, it is reasonable to assume that the pressure created by the same amount of gas would be higher in the smaller vessel. Therefore, the pressure created inside the vessel by 500 grams of oxygen gas in a 7 L vessel would most likely be greater than 100 kPa. The answer is D. greater than 175 kPa.