Question

how many moles of propane gas are in a 7.0 l tank at 20°c and 5.45atm of pressure?

Explanation:

Step1: Convert temperature to Kelvin

$$T = 20 + 273.15 = 293.15\ K$$

Step2: Use ideal gas law $PV = nRT$

We know $P = 5.45\ atm$, $V = 7.0\ L$, $R=0.0821\ L\cdot atm/(mol\cdot K)$
Rearrange for $n$: $n=\frac{PV}{RT}$
Substitute values:
$$n=\frac{5.45\times7.0}{0.0821\times293.15}$$

Step3: Calculate numerator and denominator

Numerator: $5.45\times7.0 = 38.15$
Denominator: $0.0821\times293.15\approx24.07$
$$n=\frac{38.15}{24.07}\approx1.59\ mol$$

Answer:

1.59 mol