112) Originally 2.00 mol of gas are at STP. If the temperature changes to 47.0°C and the
pressure decreases to half of what it was, how many liters do the two moles now occupy? (1 atm
= 101 kPa, R = 8.31 J/mol ∙ K)
113) How many molecules are in (a) 1.0 cm3 of air at STP and (b) 1.0 cm3 of helium at STP? (R
= 8.31 J/mol . K, NA = 6.022 × 1023 molecules/mol)
114) 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
NA = 6.022 × 1023 molecules/mol.
115) 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 NA = 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?
116) How many moles are there in 2.00 kg of copper? The atomic weight of copper is 63.5
g/mol and its density is 8.90 g/cm3.
A) 15.3
B) 31.5
C) 51.3
D) 53.1