20. Heat and Temperature

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?

(II) 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 ).

(b) 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?

"(II) 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?

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

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) Estimate the number of

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

(II) Estimate the number of

(b) molecules of water in all the Earth’s oceans.

Assume water covers 75% of the Earth to an average depth of 3 km.

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?

(II) Calculate the density of nitrogen at STP using the ideal gas law.

From the known value of atmospheric pressure at the surface of the Earth, estimate the total number of air molecules in the Earth’s atmosphere.