Question

How many moles of helium are present in a 3.00L vessel at 435 mmHg pressure and at a temperature of 25 degrees Celcius? *

Answer 1

Explanation:

How many moles of helium are present in a 3.00L vessel at 435 mmHg pressure and at a temperature of 25 degrees Celcius? *

Answer 2

Concept:

Ideal Gas Equation.

PV = nRT

where P = Pressure of the gas

V = Volume of the gas

n = Number of moles of the gas

R = Gas Constant = 0.08206 L atm mol⁻¹K⁻¹

T = Temperature in kelvin

Given:

Pressure of the helium, P = 435 mm Hg = 435/760 atm  

[to convert mm Hg to atm , we divide it by 760]

                                  P  = 0.5724 atm

Volume of the helium, V = 3.00 L

Temperature of the helium, T = 25°C = (25 + 273) K = 298 K

Find:

The number of moles of helium.

Solution:

As we know,

PV = nRT

n = PV/RT

Putting values in the above formula, we have

n = (0.5724)(3)/(0.08206)(298)

n = (1.7172)/24.45388

n = 0.0702 moles

Hence, the number of moles of helium is 0.0702.

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