What is the temperature of 1.2 moles of Helium gas at 1950 mm Hg if it occupies 15,500 ml of volume?

131°C

Explanation:

Because we are given the moles, pressure, and volume and want to find the pressure, we know that we want to use the ideal gas law: PV = nRT, where P is the pressure, V is the volume, n is number of moles, R is the gas constant, and T is temperature in Kelvins.

Here, P = 1950 mmHg, V = 15,500 mL = 15.5 L, n = 1.2 mol, and R (from a gas constant table) = 62.3638. Plug these into the equation:

(1950 mmHg) * (15.5 L) = (1.2 mol) * (62.3638) * T

Solve for T:

T ≈ 403.88 K

We can convert this to Celsius by subtracting 273 from this value:

403.88 - 273 = 130.88 ≈ 131 (3 sig figs)

Thus, the temperature is 131°C.