WWN95 79: Practice 10 X C Need Help With The Fi X Just C smartwork.wwnorton.com

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WWN95 79: Practice 10 X C Need Help With The Fi X Just C smartwork.wwnorton.com 517308&isStudent; 1 Print Calculator Periodic Table Ebook Question 15 of 15 (1 point) Thousands of buses run on compressed natural gas (CNG) to reduce pollution and to save on fuel costs. CNG, which is mostly methane, is stored on the roofs of the buses in large tanks under high pressure. If the density of CH4 in a tank at 25 C is 161g/L, use (a) the van der Waals equation and (b) the ideal gas equation to calculate the methane gas pressure Number (a) van der Waals atm Number (b) ideal gas law atm Dora

Explanation / Answer

Answer – We are given the , density of methane gas = 161 g/L

a) Pressure of methane gas by Van der Waals –

we know formula

(P + n2a/ V2) (V-nb) = nRT

We know, density = mass /volume

So, mass of methane = 161 g and volume = 1.0 L

Moles of methane gas = 161 g / 16.043 g.mol-1

                                    = 10.04 moles

For methane, a = 2.300 L2/mol2 , b = 0.04301 L/mol

Now plugging the value in the formula

(P + (10.04)2 (2.300 L2/mol2)/ (1.0 L)2) (1.0 L -10.04 mol * (0.04301 L/mol) = 10.04 moles * 0.0821 L.atm/mol.K * 298 K

0.568 P +131.77 = 245.53

0.568 P = 245.53 - 131.77

             = 113.7

So, P = 200 atm

b) From the Ideal gas law –

we know

density = PM/RT

so, P = density * RT / M

        = 161 g.L-1*0.0821 L.atm/mol.K * 298 K / 16.043 g.mol-1

        = 245.2 atm

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