2) if i have an unknown quantity of gas at a pressure of 1.2 atm, a volume of 31 liters, and a temperature…

Explanation:

Step1: Convert temperature to Kelvin

$T = 87^{\circ}C+273.15 = 360.15\ K$

Step2: Apply 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 ($R=0.0821\ \frac{L\cdot atm}{mol\cdot K}$), and $T$ is temperature. We need to solve for $n$. Rearranging the formula gives $n=\frac{PV}{RT}$.

Step3: Substitute the given values

$P = 1.2\ atm$, $V = 31\ L$, $R = 0.0821\ \frac{L\cdot atm}{mol\cdot K}$, and $T = 360.15\ K$. $n=\frac{1.2\ atm\times31\ L}{0.0821\ \frac{L\cdot atm}{mol\cdot K}\times360.15\ K}$ $n=\frac{37.2}{29.568315}\ mol\approx1.26\ mol$

Answer:

$1.26\ mol$