20. Heat and Temperature

How does the number of atoms in a 31.5-g gold ring compare to the number in a silver ring of the same mass?

If the molar mass of hydrogen is 1.008 g/mol, what is the mass (in grams) of 2 hydrogen atoms?

0.0076 moles of an ideal gas is at 24°C. If it is a sealed container with a volume of 86 cm3, what is the pressure of the gas?

How many atoms are in a 2.0 cm×2.0 cm×2.0 cm cube of aluminum?

An element in its solid phase has mass density 1750 kg/m³ and number density 4.39×10²⁸ atoms/m³. What is the element's atomic mass number?

How many atoms are there in a 3.4-g copper coin?

Calculate the number of molecules/m³ in an ideal gas at STP.

(I) If 3.50 m³ of a gas initially at STP is placed under a pressure of 2.80 atm, the temperature of the gas rises to 38.0°C. What is the volume?

How many moles of water are there in 1.00 L at STP? How many molecules?

(II) A storage tank contains 21.6 kg of nitrogen at an absolute pressure of 3.45 atm. What will the pressure be if the nitrogen is replaced by an equal mass of CO₂ at the same temperature?

(II) A storage tank at STP contains 26.5 kg of nitrogen (N₂). What is the pressure if an additional 32.2 kg of nitrogen is added without changing the temperature?

(II) A tank contains 30.0 kg of O₂ gas at a gauge pressure of 8.20 atm. If the oxygen is replaced by helium at the same temperature, how many kilograms of the latter will be needed to produce a gauge pressure of 8.00 atm?

Compare the value for the density of water vapor at exactly 100°C and 1 atm (Table 13–1) with the value predicted from the ideal gas law. Why would you expect a difference?