Gas Laws Fact Sheet

\begin{tabular}{|l|l|}
\hline
Ideal gas law & [tex]$P V=n R T$[/tex] \\
\hline
\multirow{3}{*}{Ideal gas constant} & [tex]$R=8.314\left(\frac{L \cdot kPa}{mol \cdot K}\right)$[/tex] \\
& or \\
& [tex]$R=0.0821 \left(\frac{L \cdot atm}{mol \cdot K}\right)$[/tex] \\
\hline
Standard atmospheric pressure & [tex]$1 atm=101.3 kPa$[/tex] \\
\hline
Celsius to Kelvin conversion & [tex]$K = ^{\circ}C + 273.15$[/tex] \\
\hline
\end{tabular}

The gas in a sealed container has an absolute pressure of 9.25 atmospheres. If the air around the container is at standard pressure, what is the gauge pressure inside the container?

A. [tex]$\quad 0.759 atm$[/tex]

B. 8.25 atm

C. 10.25 atm

D. [tex]$\quad 113 atm$[/tex]



Answer :

To determine the gauge pressure inside the container, we need to understand the relationship between absolute pressure, gauge pressure, and standard atmospheric pressure.

1. Absolute Pressure (Pabs): This is the total pressure within the container, which is the sum of the atmospheric pressure and the gauge pressure.
2. Standard Atmospheric Pressure (Patm): This is the pressure exerted by the Earth's atmosphere at sea level and is conventionally taken as 1 atmosphere (atm).
3. Gauge Pressure (Pgauge): This is the pressure within the container above and beyond the atmospheric pressure.

The relationship is given by:
[tex]\[ P_{\text{abs}} = P_{\text{gauge}} + P_{\text{atm}} \][/tex]

We are given the absolute pressure inside the container and the standard atmospheric pressure:
- Absolute pressure, [tex]\( P_{\text{abs}} = 9.25 \)[/tex] atmospheres
- Standard atmospheric pressure, [tex]\( P_{\text{atm}} = 1 \)[/tex] atmosphere

We need to find the gauge pressure, which can be rearranged from the above formula:
[tex]\[ P_{\text{gauge}} = P_{\text{abs}} - P_{\text{atm}} \][/tex]

Substituting the given values:
[tex]\[ P_{\text{gauge}} = 9.25 \, \text{atm} - 1 \, \text{atm} \][/tex]
[tex]\[ P_{\text{gauge}} = 8.25 \, \text{atm} \][/tex]

Therefore, the gauge pressure inside the container is [tex]\( 8.25 \)[/tex] atmospheres.

The correct answer is:
B. 8.25 atm