Liquids and Solids

Question 1

What is a solid in term of state of matter

Answer 1

A solid has a well-defined size and shape

Question 2

What is a liquid in term of state of matter

Answer 2

A liquid takes the shape of the container in which it is placed

Question 3

What is a gas in term of state of matter

Answer 3

A gas is another fluid form which can be easily compressed

Question 4

What is a phase diagram

Answer 4

A diagram showing the way in which the state of a material depends on temperature and pressure

Question 5

What are the 3 types of van der Waals forces

Answer 5

1. London forces 2. Dipole-Dipole forces 3. Hydrogen bonding

Question 6

What are London forces

Answer 6

These forces arise from the attraction between two instantaneous dipoles. The dipoles arise from fluctuations in the electron distribution model.

Question 7

Which molecules are affected by London forces

Answer 7

All molecules are drawn together by London forces

Question 8

What effect does molar mass have on London forces

Answer 8

The strength of London forces increases with molar mass since heavier molecules have more electrons

Question 9

What effect does molecular shape have on London forces

Answer 9

Rod shaped molecules can get closer together than spherical molecules meaning that London forces are stronger

Question 10

Which molecules are affected by dipole-dipole forces

Answer 10

Polar molecules (molecules with permanent partial charges) are affected by dipole-dipole forces

Question 11

What are dipole-dipole forces

Answer 11

Polar molecules are drawn together by dipole-dipole forces

Question 12

What molecules form hydrogen bonds

Answer 12

Hydrogen atoms and strongly electronegative atoms e.g. oxygen and fluorine

Question 13

What are hydrogen bonds

Answer 13

When a hydrogen atom lies between two small, strongly electronegative atoms with a lone pair of electrons

Question 14

How does water solidify

Answer 14

By hydrogen bonds

Question 15

Describe the surface tension of water molecules

Answer 15

1. The surface of a liquid is smooth because intermolecular forces pull the molecules together and inwards 2. There is a net pull inwards 3. Surface tension of water is much higher than most other liquids

Question 16

What is capillary action

Answer 16

The attraction between water and other material such as glass accounts for capillary action

Question 17

What does capillary action cause

Answer 17

The liquid rises because there are stronger forces between the water and the molecules in the surface of the capillary which results in a meniscus

Question 18

What is viscosity

Answer 18

The viscosity of a liquid is its resistance to flow

Question 19

What affect do intermolecular forces have on viscosity

Answer 19

Greater intermolecular forces result in higher viscosity, so the strong intermolecular forces reduce the ability of the liquid to flow

Question 20

What is evaporation in relation to vapour pressure

Answer 20

Molecules leave the surface of an enclosed liquid continually

Question 21

What is condensation in relation to vapour pressure

Answer 21

Molecules whilst evaporating can collide and come trapped again by the surface

Question 22

Describe the dynamic equilibrium between evaporation and condensation

Answer 22

Evaporation and condensation are temperature sensitive- at higher temperatures more molecules leave the surface

Question 23

What happens before saturated vapour pressure is reached

Answer 23

There is an increasing number of molecules in the vapour

Question 24

What happens after standard vapour pressure is reached

Answer 24

There is a constant number of molecules in the vapour

Question 25

How is boiling point defined

Answer 25

The temperature at which a liquid boils when atmospheric pressure is 1 atm

Question 26

What is boiling point

Answer 26

When the vapour pressure of a liquid matches atmospheric pressure, the liquid vaporises so quickly that bubbles form

Question 27

How do IMF affect boiling point

Answer 27

Strong intermolecular forces lead to high boiling points

Question 28

What temperature does water boil at the top of Mount Everest

Answer 28

71°C

Question 29

What is Raoult’s Law

Answer 29

The vapour pressure of a solvent in the presence of a non-volatile solute is proportional to the mole fraction of the solvent

Question 30

How is Raoult’s Law mathematically expressed

Answer 30

P = (x_solvent) x (P_pure)

x_solvent = N_solvent / (N_solvent + N_solute)

Where N_solvent and N_solute are the number of moles

Question 31

Units of pressure are important in Raoult’s Law are important- true/ false

Answer 31

False, units of pressure don’t matter

Question 32

What does the following graph show

Answer 32

A non-ideal solution

Question 33

Which molecule has a higher boiling point

Answer 33

o-Dichlorobenzene

Question 34

Which molecule has a higher boiling point

Answer 34

cis-Dichloroethene

Question 35

Which molecule has a higher boiling point

Answer 35

1,1-Dichloroethene