Calculate the number of moles and the mass of He gas present in a 2.00 L steel container if the pressure is 6.50 atm, and the temperature is 42.0°C. A)1.00 mol, 4.00 g B)0.503 mol, 2.01 g C)3.77 mol, 15.1 g D)4.99 x 10⁴ mol, 1.25 x 10⁴ g E)6.65 x 10³ mol, 2.66 x 10⁵ g

Question

Quizplus · Accepted Answer

First, we need to convert the temperature to Kelvin scale: 
42.0°C + 273.15 = 315.15 K

Then, we can use the ideal gas law to find the number of moles of He gas:

PV = nRT

n = PV/RT

n = (6.50 atm) (2.00 L) / [(0.0821 L·atm/(mol·K)) (315.15 K)]

n = 0.503 mol

Finally, we can use the molar mass of helium (4.00 g/mol) to find the mass:

mass = n x molar mass 
mass = 0.503 mol x 4.00 g/mol = 2.01 g

Therefore, the answer is B: 0.503 mol, 2.01 g

Calculate the Number of Moles and the Mass of He