Question

Consider 1 mol an ideal gas at 28∘ C and 1.06 atm pressure. To get some idea how close these molecules are to each other, on the average, imagine them to be uniformly spaced, with each molecule at the center of a small cube.
A) What is the length of an edge of each cube if adjacent cubes touch but do not overlap?

B) How does this distance compare with the diameter of a typical molecule? The diameter of a typical molecule is about 10-10 m. (in l/dmolecule)

C) How does their separation compare with the spacing of atoms in solids, which typically are about 0.3 nm apart? (in l/lsolid)

Answer 1

Answer:

A) Length of an edge = 3.38 × 10^(-9) m

B) 34 times the diameter of a molecule.

C) 11 times the atomic spacing in solids.

Explanation:

A) We will use Avogadro's hypothesis to solve this. It states that 1 mole of gas occupies 22.4 L at STP.

We want to find the volume occupied by 1 mole of gas at 1.06 atm pressure and temperature of 28 °C (= 301 K).

Thus, by the ideal gas equation, we have;

V_mole = (1 × 22.4/273) × (301/1.06) = 23.3 L = 0.0233 m³

Now, since from avogadros number, 1 mole of gas contains 6.02 x 10^(23) molecules, then volume occupied by a molecule is given by;

V_molecule = 0.0233/(6.02 × 10^(23)) m³ = 3.87 x 10^(-26) m³

Thus, length of an edge of the cube = ∛(3.87 × 10^(-26)) = 3.38 × 10^(-9) m

B) We are told that The diameter of a typical molecule is about 10^(-10) m.

Thus, the distance is about;

(3.38 × 10^(-9))/(10^(-10)) ≈ 34 times the diameter of a molecule.

C) We are told that the spacing of atoms is typically are about 0.3 nm apart

Thus;

The separation will be about;

(3.38 × 10^(-9))/(0.3 × 10^(-9)) ≈ 11 times the atomic spacing in solids.