Multiple Choice
A 22.0-g sample of an unknown gas occupies a volume of 11.2 L at STP. What could be the identity of the gas?
7. Gases
The Ideal Gas Law: Molar Mass
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Helium gas is contained in a tank with a pressure of 11.1 MPa. If the temperature inside the tank is 29.3 °C and the volume of the tank is 16.7 L, determine the mass, in grams, of the helium in the tank using the Ideal Gas Law.
A
72.3 grams
B
30.5 grams
C
44.8 grams
D
58.2 grams
Verified step by step guidance1
Convert the temperature from Celsius to Kelvin by adding 273.15 to the Celsius temperature: T(K) = 29.3 + 273.15.
Use the Ideal Gas Law equation: \( PV = nRT \), where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.
Rearrange the Ideal Gas Law to solve for n (number of moles): \( n = \frac{PV}{RT} \).
Substitute the known values into the equation: P = 11.1 MPa (convert to Pa by multiplying by 10^6), V = 16.7 L (convert to m^3 by dividing by 1000), R = 8.314 J/(mol·K), and T in Kelvin.
Calculate the mass of helium by multiplying the number of moles (n) by the molar mass of helium (4.00 g/mol): mass = n * 4.00 g/mol.
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