Question

1- a. What mass of nitrogen has the same volume as 15.00 grams of hydrogen at -25^oC and .750atm?

b. What is the density of an unknown gas at 258 K and 1.500 atm whose molar mass is 126 g/mole.

(Please type the answers, don't write them down on a paper)

Answer 1

a)

208.42g

Explanation

At same temperature and pressure , two gas having same volume if they are equal in number of moles

Number of moles = mass/molar mass

Number of moles of H2 = 15.00g/ 2.016g/mol = 7.440mol

moles of nitrogen having the same volume as 15.00g hydrogen at -25℃ = 7.440mol

mass = number of moles × molar mass

mass of nitrogen having the same volume as 15.00gams of hydrogen at -25℃ and 0.750atm

= 7.440mol × 28.014g/mol

= 208.42g

b)

Density of the unknown gas in g/L = 8.927 g/L

Density of the unknown gas in g/ml = 0.008927 g/ml

Explanation

Ideal gas equation is

PV = nRT

P = Pressure, 1.500 atm

V = Volume

n = number of moles

R = gas constant , 0.082057(L atm/mol K)

n/V = molarity

n/V = P /RT

= 1.500atm /( 0.082057(L atm /mol K) × 258K )

= 0.07085 mol /L

molar mass of unknown gas = 126g/mol

mass of 0.07085moles of unknown gas

= 0.07085mol × 126g/mol

= 8.927g

demsity = mass/volume

density of unknown gas in g/L = 8.927g/L

density of unknown gas in g/ml = 0.008927g/ml