Question

Gas Laws: Show all work, including significant figures and units, leading to your answer. 2. A scientist discovers a filled gas cylinder in an industrial facility, but cannot identify it directly because its labelling has been worn away. She determines that when a sample of 1.90 g of gas is transferred to a container, the gas occupies a volume of 2.30 L at a temperature of 298 K and a pressure of 1.00 atm. [A] How many moles are in the sample of gas? [B] What is the molar mass of the gas, in g/mol? (Hint: Your answer should be in grams per mole, so what quantities would you use to determine this?) [C] What is the identity of the unknown gas? Circle one. He Ne Ar N2 O2 CO2

Answer 1

2 (A) P=1.00 atm V=2.30L T = 298 K n = ру RT =음부 100 aflux 2.30% 0:08214 aty mot 1% x 29814 = 0.0940 mot Tholes of gas in sample = 10.0940 mot 1. (B) Molar Molar mass = mass = mass 51) 1909 - 20.2gmot'] 0.0940 mo (C) Holai mass of Neon = 20.1797 gmil- ñ 20.2gmo?" Hence, the gas is [ne]

3.80 atm So, 3.38 atm 25.0°C T2 3. Apply 1 - 2 / so, 338 ante - 3. fo atom or T = 25.0°C *3.80 atm - 3.38 atm = 28.1°C Thus, the temperature is heated upto [28.1°C . 4. Higher the vapor pressure lower is the - boiling point. Reason: Boiling point is the temperature at which the vapor pressure equals the surrounding atmospheric pressure. As the surrounding atmospheric pressure is constant, when the vapor pressure is high it will take less heat to make the vapor pressure equal to the atmospheric pressure. Hence, when vapor pressure is high, boiling point is low.

1.5 (A) a-a....a ce Dispersion between forces Ch molecules Dipole-dipole forces SH H-OH---01 (0) H Hydrogen bonding