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How many grams of F2 gas are there in a 5.00-L cylinder at 4.00 × 103 mm Hg and

ID: 906049 • Letter: H

Question

How many grams of F2 gas are there in a 5.00-L cylinder at 4.00 × 103 mm Hg and 23°C?

) How many moles of Ar are contained in a 5.00 L tank at 155°C and 2.80 atm? A) 0.399 moles B) 0.455 moles C) 1.10 moles D) 2.51 moles E) 0.289 moles

4.00-L flask contains nitrogen gas at 25 °C and 1.00 atm pressure. What is the final pressure in the flask if an additional 2.00 g of N2 gas is added to the flask and the flask cooled to -55°C?

The density of krypton gas at 1.21 atm and 50.0°C is ________ g/L. A) 0.295 B) 7.65 C) 3.82 D) 0.262 E) 0.0456

Thanks

Explanation / Answer

(1) How many grams of F2 gas are there in a 5.00-L cylinder at 4.00 × 103 mm Hg and 23°C?

We know that PV = nRT

Where

T = Temperature = 23 oC = 23+273 = 296 K

P = pressure = 4000 mmHg = 4000 / 760 atm = 5.26 atm

n = No . of moles = ?

R = gas constant = 0.0821 L atm / mol - K

V= Volume of the gas=5.00 L

n = PV / RT

= ( 5.26 x 5.00) / (0.0821 x 296)

= 1.08 mol

So mass of F2 , m = Number of moles x molar mass

                             = 1.08 mol x 38 (g/mol)

                            = 41.5 g

(2) How many moles of Ar are contained in a 5.00 L tank at 155°C and 2.80 atm?

We know that PV = nRT

Where

T = Temperature = 155 oC = 155+273 = 428 K

P = pressure = 2.08 atm

n = No . of moles = ?

R = gas constant = 0.0821 L atm / mol - K

V= Volume of the gas=5.00 L

n = PV / RT

= ( 2.80 x 5.00) / (0.0821 x 428)

= 0.399 mol

(3)The density of krypton gas at 1.21 atm and 50.0°C is ________ g/L

We have PV = nRT

                    = (w/M) RT

            PM = (w/V) RT

           PM = dRT

Where d = density = mass(m) / Volume (V)

So d = PM / RT

P = pressure = 1.21 atm

M = molar mass = 83.8 (g/mol)

R = gas constant = 0.0821 Latm/mol-K

T = temperature = 50 oC = 50+273 = 323 K

Plug the values we get

d = PM / RT

   = (1.21 x 83.8) / (0.0821 x323)

   = 3.82 g/L

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