7. An unknown gas has a density of 1.686 g/L when the pressure is 2.503 atm and

Question

7. An unknown gas has a density of 1.686 g/L when the pressure is 2.503 atm and the temperature is
35.0 oC. What is the molecular weight of this gas? Note that the gas constant R has the value

0.08205 L atm / K mol.

  a) 2.015 g/mol  b) 4.003 g/mol  c) 17.03 g/mol  d) 28.01 g/mol  e) 44.01 g/mol

8. What is the identity of the unknown gas in the previous problem? The following atomic weights will be
helpful in working out your answer to this problem: H = 1.008 g/mol  C = 12.01 g/mol

N = 14.01 g/mol  O = 16.00 g/mol  He = 4.003 g/mol

  a) CO    b) CO2    c) H2    d) He    e) NH3

Explanation / Answer

Q7

D =1.686 g/L

P = 2.503 atm

T = 35°C = 308 K

find MW

PV = nRT

n = mass/MW

PV = mass/MW*RT

MW = mass/V*RT/P

MW = 1.686 * 0.082 * 308 / 2.503 = 17.0122 G/mol

most likely NH3 ammonia

choose C and then E

Related Questions

Navigate

• Browse (All)
• Browse 7
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.