Matter

Question 1

What is The Kinetic Theory of Matter?

Answer 1

all gas molecules, regardless of size, are in constant motion

some have more kinetic energy than others, but none will be static at any given point in time

gives rise to many gases intrinsic properties

Question 2

Name and briefly describe the 5 intrinsic properties of gases

Answer 2

low density - a lot of space between molecules, expand to fill space

pressure exertion - constant motion = collisions = pressure on container wall

diffusibility - mix gases evenly

no definitive shape - expand to occupy whatever space they’re in

compressibility - vast space between molecules allows gas expansion and compression

Question 3

What is the “Ideal Gas Law”?

Answer 3

a way of bringing together the different aspects of a gas, relating temperature, pressure, volume and the molar quantity of a gas

limitation - assumes the gas is an ideal gas

uses- in reality, a gas will have a lot of different properties and the notion of an ideal gas describes a model with which a real gas can be examined in

Question 4

What are the main properties of an ideal gas?

Answer 4

gas molecules do not attract or repel each other

the volume of one individual gas molecule is negligible

no energy gained or lost through elastic collisons

Question 5

What is the “Ideal Gas Law” equation?

Answer 5

PV = nRT

P = pressure (Pa)
V = volume (m3)
n = moles of gas
R = ideal gas constant (8.31 J/K mol)
T = temperature (Kelvin)

Question 6

What is the difference between a “solute” & “solvent”

Answer 6

solute - a small component that dissolves in a given solution

solvent - a large component in which the solute is dissolved in

Question 7

What are the 4 colligative properties of a solution?

Answer 7

vapour pressure - the likelihood of any particular solution evaporating/ forming a vapour at a given temperature

osmotic pressure - the pressure required to prevent osmotic flow towards the solution

boiling point

freezing point

Question 8

What are the consequences when you increase the concentration of a solute in a solution?

Answer 8

increase in boiling point

decrease in freezing point

decrease in vapour pressure

Question 9

What occurs when you increase the boiling point of a solution?

Answer 9

freezing point decreases - particles are impeding this process of bonding

vapour pressure decreases - solution boils less readily

Question 10

State and briefly describe the 4 key factors that affect solubility

Answer 10

Pressure - gases may become more soluble when pressure increases, liquid and solids unaffected

Temperature - solutes may become more soluble when temperature increase

Polarity - like solutes and solvents will easily dissolve

Molecular Size - larger particles or molecules as solutes are less soluble

Question 11

Define “Concentration”

Answer 11

the amount of solute in a particular volume of solvent
n/V = C

n = number of moles - Mass/molar mass
V = volume (L)
C = concentration (M or mol/L)

Question 12

What are the properties of “Ionic Solids”?

Answer 12

Texture - hard and brittle

Melting point - high

Conductivity - poor conductors when solid but when aqueous is a good conductor

Question 13

What are the properties of “Molecular Solids”?

Answer 13

Texture - soft due to weak forces

Melting Point - low due to weak forces

Conductivity - unable to conduct electricity as electrons remain within the respective molecules

only exists at sufficiently low temps

Question 14

What are the properties of “Metallic Solids”?

Answer 14

Texture - shiny and malleable

Melting Point - high due to sea of delocalised electrons

Conductivity - great conductors of heat and electricity

Question 15

What are the properties of “Covalent Network Solids” with examples?

Answer 15

3D covalent network solids are extremely hard - e.g Diamonds

2D covalent network solids are soft, as the bonds between layers are weak intermolecular forces - e.g Graphite

Question 16

What is the difference between intra and inter-molecular forces?

Answer 16

Intra - strong attraction that binds together atoms in a compound/molecule

Inter - weaker attraction between molecules

Question 17

What is the difference between polar and non-polar molecules?

Answer 17

Polar molecules - constant fixed dipole moment e.g molecules with highly electronegative element

Non-polar molecules - do not have a fixed charge, but can still have temporary, transient dipole moments e.g hydrocarbons and symmetrical molecules with highly electronegative elements

Question 18

What are the 3 main intermolecular forces?

Answer 18

London/ Dispersion Forces

Dipole-Dipole Attractions

Hydrogen Bonds

Question 19

What are London/Dispersion Forces?

Answer 19

primary force in non-polar molecules and hydrocarbons where temporary and transitionary dipole moments form between molecules

strength of forces increases with the size of the molecule as the number of transitionary dipole moments increase

Question 20

What are Dipole-Dipole attractions?

Answer 20

dipole moment - the differences in charge between the atoms in molecules, based on their differences in electronegativity

the fixed d+/d- of a dipole moment in one polar molecule is attracted via electrostatic charge to the fixed d+/d- dipole moment in another polar molecule creating an intermolecular force

Question 21

What is hydrogen bonding?

Answer 21

occurs in polar molecules that contain a constant, fixed dipole moment between a highly electronegative atom (F/O/N) and hydrogen

Question 22

What is a phase change, and what are the phase changes of matter?

Answer 22

reversible movements from one state to another caused by changes in spatial relationship

Question 23

What physical conditions affect the spatial relationship in phase change?

Answer 23

Temperature - breaks weak intermolecular forces between molecules

Pressure - increasing pressure will make a system more ordered