20. Heat and Temperature

"(II) Estimate the number of moles. Assume water covers 75% of the Earth to an average depth of 3 km."

Estimate how many molecules of air are in each 2.0-L breath you inhale that were also in the last breath Galileo took. Assume the atmosphere is about 10 km high and of constant density. What other assumptions did you make?

(II) Estimate the number of molecules of water in all the Earth’s oceans. Assume water covers 75% of the Earth to an average depth of 3 km.

Estimate the number of air molecules in a room of length 6.0 m, width 3.0 m, and height 2.5 m. Assume the temperature is 22°C. How many moles does that correspond to?

(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?

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?

(III) A sealed container containing 3.5 mol of gas is squeezed, changing its volume from 0.020 m³ to 0.018 m³. During this process, the temperature decreases by 9.0 K while the pressure increases by 450 Pa. What were the original pressure and temperature of the gas in the container?

The gauge pressure in a helium gas cylinder is initially 28 atm. After many balloons have been blown up, the gauge pressure has decreased to 5 atm. What fraction of the original gas remains in the cylinder?

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

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

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?

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?

(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?

What is the pressure in a region of outer space where there is 1 molecules/m³ and the temperature is 3 K?