Exam 10: Gases

A jar holds 2.0 L of ideal nitrogen gas,N₂,at STP.The atomic mass of nitrogen is 14.0 g/mol,the ideal gas constant is R = 8.31 J/mol ∙ K,Avogadro's number is N_A = 6.022 × 10²³ molecules/mol,and 1.00 atm = 101 kPa. (a)How many moles of nitrogen are in the jar? (b)How many nitrogen molecules are in the jar? (c)What is the mass of the nitrogen in the jar?

An oxygen molecule,O₂,falls in a vacuum.From what height must it fall so that its translational kinetic energy at the bottom of its fall equals the average translational kinetic energy of an oxygen molecule at 920 K? The mass of one O₂ molecule is 5.312 × 10^-26 kg,and the Boltzmann constant is 1.38 × 10^-23 J/K.Neglect air resistance and assume that g remains constant at 9.8 m/s² throughout the fall of the molecule.

A balloon originally has a volume of 1.0 m³ when the gas in it is at 20°C and under a pressure of 1.0 atm.As it rises in the earth's atmosphere,its volume expands.What will be its new volume if its final temperature and pressure are -40°C and 0.10 atm?

If a certain sample of an ideal gas has a temperature of 104°C and exerts a pressure of 2.3 × 10⁴ Pa on the walls of its container,how many gas molecules are present in each cubic centimeter of volume? The ideal gas constant is R = 8.31 J/mol × K and Avogadro's number is N_A = 6.022 × 10²³ molecules/mol.