Concept:When dealing with non-standard conditions (not STP), we must use the Ideal Gas Law to link Pressure, Volume, Temperature, and Moles.
Formula:$$ PV = nRT \rightarrow n = \frac{PV}{RT} $$
Solution:- Pressure (P) = 0.83 atm.
- Volume (V) = 30.57 L.
- Temperature (T) = \( 55^\circ\text{C} + 273 = 328 \text{ K} \).
- Universal Gas Constant (R) = 0.0821 L atm / (mol K).
- Substitute: \( n = \frac{0.83 \times 30.57}{0.0821 \times 328} \).
- Numerator: \( 0.83 \times 30.57 \approx 25.37 \).
- Denominator: \( 0.0821 \times 328 \approx 26.93 \).
- \( n = 25.37 / 26.93 \approx 0.94 \text{ moles} \).
Why other options are incorrect:- 0.1, 0.62, 0.84 mol: These values result from forgetting to convert Celsius to Kelvin, or using an incorrect value for the Gas Constant 'R' (such as 8.314, which applies strictly to J/mol K and cubic meters, not Liters and atm).
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