Chapter 18: A Macroscopic Description of Matter

What is the number density of (a) aluminium and (b) lead?

An element in its solid phase has mass density 1750 kg/m3

and number density 4.3

a. A sample of water vapour in an enclosed cylinder has an initial pressure of 500 Pa at an initial temperature of -0.01°C. A piston squeezes the sample smaller and smaller, without limit. Describe what happens to the water as the squeezing progresses.

b. Repeat part a if the initial temperature is 0.03°C warmer.

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

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

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

1.0 mol of gold is shaped into a sphere. What is the sphere’s

diameter?

A rigid container holds $2.0mol$of gas at a pressure of $1.0atm$and a temperature of $30°C$.

a. What is the container’s volume?

b. What is the pressure if the temperature is raised to $130°C$?

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?

A $6.0cm-\mathrm{diameter},10cm-\mathrm{long}$cylinder contains $100mg$of oxygen (O₂) at a pressure less than $1atm$. The cap on one end of the cylinder is held in place only by the pressure of the air. One day when the atmospheric pressure is $100kPa$, it takes a $184N$force to pull the cap off. What is the temperature of the gas?

To determine the mass of neon contained in a rigid, $2.0L$cylinder, you vary the cylinder’s temperature while recording the reading of a pressure gauge. Your data are as follows:

Use the best-fit line of an appropriate graph to determine the mass of the neon.