Question

1. if the pressure exerted by a gas at 25 degrees c in a volume of 0.044 l is 3.81 atm, how many moles of gas are present?

.002766 mol
2.766 mol
.0069 mol
9.887 mol

1. 25 degrees celsius is ______ k

-248
125
298
-125

Explanation:

Step1: Convert Celsius to Kelvin

The temperature $T$ in Kelvin is $T = 25+ 273=298\ K$.

Step2: Use the ideal - gas law

The ideal - gas law is $PV = nRT$, where $P$ is pressure, $V$ is volume, $n$ is the number of moles, $R$ is the ideal - gas constant ($R = 0.0821\ L\cdot atm/(mol\cdot K)$), and $T$ is temperature. We need to solve for $n$, so $n=\frac{PV}{RT}$. Given $P = 3.81\ atm$, $V = 0.044\ L$, $R = 0.0821\ L\cdot atm/(mol\cdot K)$, and $T = 298\ K$.
\[n=\frac{3.81\ atm\times0.044\ L}{0.0821\ L\cdot atm/(mol\cdot K)\times298\ K}\]
\[n=\frac{0.16764}{24.4658}\ mol\approx0.0069\ mol\]

Answer:

1. C. 0.0069 mol
2. C. 298