Chapter 18: A Macroscopic Description of Matter

The atomic mass number of copper is A = 64. Assume that atoms in solid copper form a cubic crystal lattice. To envision this, imagine that you place atoms at the centers of tiny sugar cubes, then stack the little sugar cubes to form a big cube. If you dissolve the sugar, the atoms left behind are in a cubic crystal lattice. What is the smallest distance between two copper atoms?

The molecular mass of water (H2O) is A = 18. How many protons are there in 1.0 L of liquid water?

A brass ring with inner diameter 2.00 cm and outer diameter 3.00 cm needs to fit over a 2.00-cm-diameter steel rod, but at 20$°$C the hole through the brass ring is 50 mm too small in diameter. To what temperature, in$°$C, must the rod and ring be heated so that the ring just barely slips over the rod?

A 15$°$C, 2.0-cm-diameter aluminum bar just barely slips between two rigid steel walls 10.0 cm apart. If the bar is warmed to 25$°$C, how much force does it exert on each wall?

The semiconductor industry manufactures integrated circuits in large vacuum chambers where the pressure is 1.0 * 10-10 mm of Hg.

a. What fraction is this of atmospheric pressure?

b. At T = 20$°$C, how many molecules are in a cylindrical chamber 40 cm in diameter and 30 cm tall?

A nebula—a region of the galaxy where new stars are forming—contains a very tenuous gas with $100atoms/c{m}^3$ . This gas is heated to $7500K$ by ultraviolet radiation from nearby stars. What is the gas pressure in atm?

On average, each person in the industrialized world is responsible for the emission of $10,000kg$of carbon dioxide (data-custom-editor="chemistry" ${\mathrm{CO}}_2$) every year. This includes ${\mathrm{CO}}_2$that you generate directly, by burning fossil fuels to operate your car or your furnace, as well as ${\mathrm{CO}}_2$generated on your behalf by electric generating stations and manufacturing plants. ${\mathrm{CO}}_2$ is a greenhouse gas that contributes to global warming. If you were to store your yearly ${\mathrm{CO}}_2$ emissions in a cube at STP, how long would each edge of the cube be?

How many moles are in a 2.0 cm * 2.0 cm * 2.0 cm cube of

copper?

A gas is in a sealed container. By what factor does the gas temperature change if:

a. The volume is doubled and the pressure is tripled?

b. The volume is halved and the pressure is tripled?

The $3.0-m$ -long pipe in FIGURE P18.50 is closed at the top end. It is slowly pushed straight down into the water until the top end of the pipe is level with the water’s surface. What is the length $L$of the trapped volume of air?