Problems
1.1 A cube is placed on the ground. The density of the material of the cube is 1 kg/l. What is
the pressure exerted on the ground by the cube if the length of an edge is (a) 0.1 m, and
(b) 0.01 m? The acceleration of gravity is 9.81 m s−^2.
1.2 If we were to isothermally compress an ideal gas from 4 L to 2 L, resulting in a final pressure
of 6 atm, what was the original pressure?
1.3 Express a pressure of 202.6 Pa in terms of the following units: (a) atm, (b) bar.
1.4 Express the following temperatures on the Kelvin scale: (a) 0°C, (b) −270°C, (c) 100°C.
1.5 The absolute temperature of a system is related to what properties of the molecules that
form the system?
1.6 Using the van der Waals equation and assuming a temperature of 298 K and a volume of
25 L calculate the pressure of 1 mol of carbon dioxide gas (use aand bvalues in Table 1.3).
1.7 What is the pressure exerted by 0.1 mol of an ideal gas in a 2-L chamber at 25°C?
1.8 Calculate the number of molecules in 2 L of air at a pressure of 1 atm and a temperature of
10°C, assuming ideal gas behavior.
1.9 If a helium balloon has an initial volume of 1 L at 25°C but a final volume of 0.95 L after
a temperature change, what is the final temperature?
1.10 The mass percentage of dry air is approximately 75.5% for nitrogen, 23.2% for oxygen, and
1.3% for argon. What is the partial pressure of each gas when the total pressure is 1 atm?
To calculate the mole fractions use densities of 28.02, 32.0, and 39.9 g mol−^1 for nitrogen,
oxygen, and argon respectively.
1.11 What is the composition of a cell membrane?
1.12 How are the lipids arranged in a cell membrane?
1.13 What is the fluid-mosaic model of a cell membrane?
1.14 What is the structure of an amino acid?
1.15 How many different types of amino acid are commonly found in proteins?
1.16 How are the atoms of an amino acid designated?
1.17 What isomer form of the amino acid is found in proteins?
1.18 Which amino acid residues can be (a) positively charged, (b) negatively charged?
1.19 Which amino acid has a cyclic structure?
1.20 Which amino acid residues have aromatic side chains?
1.21 What reaction can cysteine undergo?
1.22 What bases are present in DNA?
1.23 What are the characteristics of a double helix of DNA?
1.24 What is the base-pairing arrangement in the double helix?
1.25 How does RNA differ from DNA?