1 - States, Pressure and Solutions

Question 1

What four types of defect might you expect to find in a crystal?

Answer 1

Vacancies
Interstitial Defects
Line Defects
Planar Defects

Question 2

What are crystal vacancy defects?

Answer 2

When an atom/molecule is missing from its place in the crystal.

Question 3

What are crystal insterstitial defects?

Answer 3

An extra molecule squeezed in between the usual pattern locations.

Question 4

What are crystal line defects?

Answer 4

Where the plane of a pattern stops abruptly along its length, leaving a distortion as the others curve to compensate.

Question 5

What are crystal planar defects?

Answer 5

Complete misalignment on either side of a plane.

Question 6

What are non-crystalline solids called, and how are they defined?

Answer 6

Amorphous - no long range order.

Question 7

What are the defining features of a liquid?

Answer 7

Atoms are free to move relative to each other, and although being dense to the point of incompressibility have some free space which allows them to flow.

Question 8

How is the order of liquids describes?

Answer 8

No long range order, but some transient local/short-range order often form and break up.

Question 9

What are the defining characteristics of gases?

Answer 9

Far less dense than liquids, all molecules in constant random motion. Collisions are rare, but can lead to dimerisation that may be long or short lived depending on the intermolecular forces and the speed of collision.

Question 10

What is the pressure of a gas equal to?

Answer 10

Force exerted by molecules/Area of container walls

Question 11

What is the force with which the molecules strike the contained equal to?

Answer 11

Rate of change of momentum = mass x acceleration

Question 12

What is a plasma, and how does its composition affect its properties?

Answer 12

A gas which has been partially ionised, causing the electrons and molecules to form the neutral plasma. The strong ionic attraction causes very different properties to a gas.

Question 13

What are some other, more strange states of matter?

Answer 13

Glasses, Liquid Crystals, Superfluids, Quark-Gluon Plasmas, Soft Consensed Matter.

Question 14

What are examples of psuedo-states of matter?

Answer 14

Lipid bilayers/micelles.

Question 15

What is the definition of a solution?

Answer 15

A homogenous mixture of two or more distinct chemicals. This does not preclude non-liquid solutions.

Question 16

What is Relative Permittivity a measure of?

Answer 16

Polarity; or more properly, the ability to store electrical energy by concentrating lines of flux.

Question 17

What is viscosity (eta) a measure of?

Answer 17

Resistance to flow.

Question 18

What are ionic and non-ionic solutes termed?

Answer 18

Electrolytes and non-electrolytes respectively.

Question 19

Define an ideal solution.

Answer 19

One where all intermolecular interactions (two solvent, two solute of solvent-solute) have equal energy. Hence they behave as is a pure liquid containing only one of them would.

Question 20

What are the three categories of Van der Waals interactions?

Answer 20

Keesom Forces
Debye Forces
London Forces

Question 21

What are Keesom Forces?

Answer 21

Permanent dipole - permanent dipole interactions.

Question 22

What are Debye Forces?

Answer 22

Permanent dipole - induced dipole interactions.

Question 23

What are London Forces?

Answer 23

Instantaneous dipole - induced dipole interactions.

Question 24

What is the disadvantage of using molarity to measure concentration instead of molality?

Answer 24

The molarity of a solution will change with the temperature as this effects the volume of the solution.

Question 25

What is Vapour Pressure?

Answer 25

The pressure of the gas in a container produced at equilibrium levels of evaporation/condensation of the liquid.

Question 26

What is Partial Pressure?

Answer 26

The proportion of the total pressure of a contained equilibrium evaporation/condensation system that is caused by one of the components of a solution.

Question 27

What is Raoult’s Law?

Answer 27

That the partial pressure of a solute or solvent is equal to the partial pressure of a pure sample of that substance multiplied by the mole fraction in the solution.

Question 28

What kind of solutions obey Raoult’s Law?

Answer 28

Ideal ones.

Question 29

When do non-ideal solutions obey Raoult’s Law?

Answer 29

In very dilute solutions, known as Ideal-Dilute solutions, the solvent does but not the solute.

Question 30

Why do Ideal-Dilute solutions show the properties of ideality?

Answer 30

Because there is so much more solvent than solute that almost all intermolecular interactions are solvent-solvent, and therefore have the same energy.

Question 31

What is Henry’s Law?

Answer 31

That the partial pressure of the solutes in ideal-dilute solutions vary linearly with small changes in mole fraction, being equal to the partial pressure of a pure sample of the solute multiplied by an experimentally determined constant, K, which will be different from the mole fraction.

Question 32

In ideal-dilute solutions, which partial pressure laws do the solvent and solute obey?

Answer 32

Solvent - Raoult’s Law

Solute - Henry’s Law

Question 33

How do macromolecules affect ideality?

Answer 33

Macromolecule solutions exhibit highly non-ideal properties due to the high effects of entropy and drag produced by the bulky molecules made bulkier by a solvent cage.