0.249 g of a diatomic element occupies a volume of 125. mL at 120. °C and 2.00 atm. This element is ________.

Question

Quizplus · Accepted Answer

Using the ideal gas law, PV = nRT, and the molar mass, we can identify the element. First, convert the given conditions to standard units: V = 125 mL = 0.125 L, T = 120 °C = 393.15 K, P = 2.00 atm. The ideal gas constant R = 0.0821 L·atm/(mol·K). Rearrange the ideal gas law to solve for n (moles of gas): n = PV/(RT). Substituting the given values: n = (2.00 atm * 0.125 L) / (0.0821 L·atm/(mol·K) * 393.15 K) ≈ 0.0077 moles. The molar mass (M) is the mass of the gas divided by the number of moles: M = 0.249 g / 0.0077 moles ≈ 32.3 g/mol. This molar mass is closest to that of oxygen (O2), which is approximately 32 g/mol.

0249 G of a Diatomic Element Occupies a Volume of 125