Determine the volume (in L) of 4.80 g of He gas at 25.0 °C and 780. mmHg. Be sure your answer has the correct number of significant figures.
Note: Reference the Fundamental constants and Conversion factors for non-SI units table for additional information.
To determine the volume of helium gas at the given conditions, we can use the ideal gas law equation:
PV = nRT
Where:
P = pressure = 780. mmHg = 780. mmHg * (1 atm / 760 mmHg) = 1.02631578947 atm
V = volume
n = moles of gas
R = ideal gas constant = 0.08206 L atm / mol K
T = temperature = 25.0 °C = 25.0 + 273.15 = 298.15 K
First, we need to determine the number of moles of helium gas:
4.80 g * (1 mol He / 4.002602 g) = 1.2004772449 mol
Now, we can substitute the values into the ideal gas law equation and solve for V:
V = (1.2004772449 mol) * (0.08206 L atm / mol K) * (298.15 K) / 1.02631578947 atm
V = 29.06 L
Therefore, the volume of 4.80 g of helium gas at 25.0 °C and 780. mmHg is 29.06 L (rounded to four significant figures).