| What is the kinetic assumptions are made when dealing with ideal gas? (5) | 1. The gas contains a large number of molecules moving in random direction at random speeds
2. Electrostatic forces between molecules is negligible, except during collisions.
3. Collisions are perfectly elastic
4. Time of collision between molecules is negligible compared to time between collisions
5. The molecules of a gas occupy negligible volume compared to the total volume of the gas. |
| What is the conditions necessary for a gas to approach ideal behavior? | - Low pressure
- High temperature |
| What are the limitation of an ideal gas at very low temperatures and very high pressures? | - Intermolecular forces are no longer negligible and have to be considered.
- Molecular size is also no longer negligible and has to be considered |
| What is the ideal gas equation? | pV=nRT
p- pressure (Pa)
V- volume (m^3)
n- number of moles (mol)
R- gas constant (8.314 J K^-1 mol^-1)
T- temperature (K) |
| The ideal gas equation can be used with which other equation to find molecular mass? | M = m/n
M - molecular mass
n - number of moles (mol)
m - mass (g) |
| Use the kinetic- molecular model to describe the liquid state
(3) | - Particles are close together but not regularly arranged
- Particles have a little more kinetic energy than in a solid
- There are fewer electrostatic forces between particles than in a solid, allowing particles to move past each other and flow |
| In terms of the kinetic-molecular model, what happens during melting? (3) | - Solid ~> Liquid
- Increasing the temperature of the surroundings causes particles to absorb energy meaning they gain more kinetic energy
- Eventually, the particles gain enough energy to disrupt the regular arragement and become a liquid |
| How do particles act during vaporiastion? | - Liquid ~> Gas
- Heat energy causes particles in a liquid to move fast enough to break all forces of attraction between them and become a gas. |
| What is vapour pressure? | When a liquid evaporates in a closed container, the gaseous particles move around above the liquid
When these particles collide with the walls of the container, they exert a pressure called the vapour pressure |
| Describe the structure of a solid ionic compound. | - Regular, repeating arrangement (lattice)
- Caused by the electrostatic attraction between the oppositely charged ions |
| Describe the lattice structure of iodine | - Iondien is a exaple of a simple molecular lattice
- Iodine, I2 molecules form a larger structure due to intermolecular forces (van der Waals' Forces ) between molecules.
- The structure is described as face centred cubic |
| What is a allotrope | Allotropes are different physical forms of elements in the same state |
| Describe the structure of a fullerene | Lattice structure |
| What is a nanotube | A graphene sheet rolled up into a tube (single sheet of carbon atoms covalently bonded together) |
| Describe the structure of diamond | - Giant covalent lattice
- Each carbon atom is covalently bonded to 4 other carbon atoms
- Extremely strong structure
- Bond shape and angle around each carbon: Tetrahedral, 109.5* |
| Describe the structure of graphite | - Giant covalent lattice
- Made from layers of carbon arranged in hexagonal rings
- There are weak london forces between layers
- Each carbon atoms bonds covalently to 3 other carbon atoms.
- One delocalised electrons per carbon |
| Describe the structure of graphene | - Giant covalent lattice
- Single layer of graphite
- Each carbon atom is bonded to 3 other carbon atoms to create a hexagonal ringed structures
- One delocalised electrons per carbon |
| Describe the structure of silicon(IV) oxide | - Similar 3D structure to diamonds
- Silicon and oxygen atoms covalently bonded together |
| Describe the structure of ice | - Open lattice structure
- Hydrogen bonds hold water molecules apart in hexagonal rings |
| Describe the structure of a metal (e.g. copper) | - Gaint metallic lattice with positive ions packed closely together with delocalised electrons
- In copper, each atom is surrounded by 12 other copper atoms |
| What is a finite resource? | A resource that is used faster than it is replaced. This resource will run out if it is continually used |
| Why is recycling important? | - To conserve finite resources for as long as possible by reducing the rate at which they are used
- Reduced greenhouse gas emmisions (which cause global warming)
- May reduce costs and other environment impacts of a material |
| How does hydrogen bonding affect the boiling points of a substance? | Hydrogen bonding is the strongest type of intermolecular bond and hence requires a lot of energy to overcome when boiling / melting a substance
As a result, structures that contain hydrogen bonding often have higher melting and boiling points than expected |
| How does hydrogen bonding affect the viscosity of a substance? | Hydrogen bonds increase viscosity of a substance because these bonds (as well as intermolecular forces) make the substance more resistance to flow |
| How does hydrogen bonding create surface tension in water? | Hydrogen bonding increases surface tension
Water molecules at the surface of the liquid are attracted more strongly to other water molecules around them than the layer of water molecules below, creating tension at the surface of the liquid. |
| What does boiling point suggest about stucture and bonding? | A high boiling point indicates a giant structure (ionic metallic or giant covalent).
A low boiling point indicates simple molecules (or atoms for noble gases). |
| What does solubility suggest about structure and bonding ? | Compounds that are soluble in water tend to be ionic
If a soluble compound has a low boiling point, it may be small and very polar or able to form hydrogen bonds |
| What does electrical conductivity suggest about structure and bonding? | If a solid substance conducts electricity, it is likely to be a metal, graphene or graphite
If a substance only conducts when molten or dissolved, it is an ionic compound. |
