Sam asked in Science & MathematicsChemistry · 6 years ago

# Need help with Chemistry homework please?

1) 45g of neon gas is in a 3.50 liter container at 44 degrees C. What is the pressure inside the container in mm Hg?

2) .89 moles of argon is in a closed container at a pressure of 2.5atm and a temperature of -44 degrees C. What is the volume of the container in mL?

3) A sample of oxygen gas is at 25 degrees C in a 2.5 L container with a pressure of 400 mmHg. What is the mass of the oxygen gas in the container?

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• 6 years ago

match R with units in each problem: http://en.wikipedia.org/wiki/Gas_constant

T should be kelvins

n = mass / molar mass = m/M

PV = nRT

PV = (m/M)RT

1)

PV = (m/M)RT

V = 3.50 L

P = ?mm Hg

∴ R = 62.36367 L mmHg K⁻¹ mol⁻¹

P = (45g / 20.2g mol⁻¹)( 62.36367 L mmHg K⁻¹ mol⁻¹)(317K) / (3.50L)

P = 12583 mmHg

2)

PV = nRT

P = 2.5 atm

V = ? mL (get V in liters and then convert to mmL)

∴R = 0.08205746 L atm  K⁻¹ mol⁻¹

V = (0.89 mol)( 0.08205746 L atm  K⁻¹ mol⁻¹) (229 K) / (2.5 atm)

V = 6.689 L

V = 6689 mL

3)

PV = (m/M)RT

V = 2.5 L

P = 400 mm Hg

∴ R = 62.36367 L mmHg K⁻¹ mol⁻¹

m/M = PV /( RT)

m = MPV / (RT)

m = (32.0 g mol⁻¹)(400 mmHg)(2.5 L) /((62.36367 L mmHg K⁻¹ mol⁻¹)(298K))

m = 1.72 g