Chapter 4. States Of Matter Flashcards
What is vapor pressure
The force exerted by gas particles colliding against the walls of a container.
What are the assumptions on an ideal gases
-They have zero particle volume
-They have no intermolecular forces of attraction between their molecules
-They are made of particles in rapid and random motion
-The temperature of the gas is directly proportional to the average kinetic energy of the particles
-Collisions between an ideal gas’ particles are perfectly elastic
-Their molecules behave as rigid spheres
Why do gases deviate from ideal gas behavior
-particles in a real gas have large molecules (their volume is not zero)
-real gas molecules have intermolecular forces
What are the conditions necessary for a real gas to approach ideal gas behavior
-very high temperatures
-very low pressures
State Boyle’s law
The product of pressure and volume is a constant provided temperature is constant
pv=constant
Sate Charles’ law
The volume is proportional to the temperature provided pressure remains constant
v/T = constant
State Gay-Lussac’s law (constant volume law)
Pressure is directly proportional to the temperature as long as volume remains constant
P/T = constant
Sate the ideal gas equation
pV = nRT where p(Pa) = pressure, V(m^3) = volume, n = number of moles, R = gas constant(JK^-1mol^-1) and T(K) = temperature
How many cubic cm are equal to one cubic metre
1 000 000
How do you convert temperature from degrees Celsius to Kelvins
You add 273 to the temperature in degrees
Explain what is meant by structure and give the two types of structures
Structure describes the geometrical arrangement of the atoms in space. The two types are giant structure where the atoms form an extended geometrical arrangement and the the other is molecular structure which consists of separate molecules.
How do substances allow electricity to pass through them
A current of electricity is a flow of charge. In metals, negative electrons move. In ionic compounds, charged ions move.
What is a lattice
A regular arrangement of ions which continues throughout the solid.
What is coordination number
This is the number of ions that surround an ion for example in NaCl, the coordination number of sodium is 6 because it is surrounded by 6 chloride ions same for chlorine thus NaCl has a 6,6 coordination number
Properties of ionic compounds
- High melting points because a lot of energy is required to break the strong forces of attraction between positive ions and negative ions.
- The structure is rigid and brittle
- They are usually soluble in aqueous solvents
- In solid state they are non-conductive of electricity because ions are in fixed positions. When molten or in aqueous solution they conduct electricity because ions are free to move from one place to another.
Properties of molecular crystals
- Low melting and boiling points because the Van dear Waal’s forces require very little energy to break because they are weak
- Non conductor of electricity in any state because no charged particles are present
- Low solubility in water because iodine molecules can not form hydrogen bonds with water
Properties of buckminsterfullerene
- Low sublimation point turns directly from solid to gas when heated at 6000C because of weak van der waal’s forces between its molecules
- Soft because it requires very little energy to overcome weak van der waal’s forces
- It is a poor conductor of electricity compared to graphite because the extent of electron delocalization is lower
- It is more reactive compared to graphite or diamond (reacts with H2, O2, F2, Cl2 and Br2) because of the relatively higher electron density in certain parts of the molecules.
Properties of diamond
- Very hard
- Very high melting point
- Does not conduct electricity
Properties of graphite
- Graphite is a soft material
- It has a very high melting point and in fact it breaks down before it melts. This is because of the strong network of covalent bonds, which make it a giant structure.
- It conducts electricity along the planes of the hexagons
Properties of silicone dioxide
- It is hard due to very strong covalent bonds
- Has a high melting and boiling point because the very strong silicon-oxygen covalent bonds have to be broken through the structure before melting
- It does not conduct electricity. There are no delocalized electrons and no ions
- It is insoluble in water and organic solvents. There are no possible attractions which could occur between solvent molecules and silicon or oxygen atoms resulting in overcoming the covalent bonds in the structure.
Factors affecting the strength of metallic bonding
- Number of protons-the more the number of protons the stronger the force of attraction between the positive ions and the delocalized electrons
- Number of delocalized electrons per atom - the more the stronger
- Size of the atom - the smaller the stronger
Properties of metals
- High melting points
- Malleable
- Ductile
- Conduct electricity
What is vapor pressure?
The pressure caused by the gas particles colliding against the walls of the container.
What are the three gas laws?
- Boyle’s law: The volume of a fixed mass of a gas at a fixed temperature is inversely proportional to the applied pressure.
pV = constant and P1V1 =P2V2 - Charles’ law: The volume of a fixed mass of a gas is directly proportional to the absolute temperature provided the pressure remains constant.
V/T = constant - The “constant volume” law(Gay-Lussac’s law): The pressure of a fixed mass of a gas is directly proportional to the absolute temperature provided its volume remains constant.
P/T = constant
What is the ideal gas equation?
pV = nRT
where:
p is pressure in Pa(Nm-2)
V is the volume in m3
n is number of moles(mol)
R is 8.31JK-1mol-1
T is temperature in K
What are the basic assumptions of an ideal gas?
- Ideal gases have zero particle volume.
- There are no intermolecular forces of attraction between the molecules of an ideal gas.
- All collisions between molecules of an ideal gas are perfectly elastic. (i.e. There is no loss of kinetic energy during collisions.)
- The temperature of the gas is related to the average kinetic energy of the molecules.
- The gas molecules move rapidly and randomly.
- The molecules of an ideal gas behave as rigid spheres
Note: The volume is negligible not necessarily zero
Why do real gases deviate from ideal gas?
- Particles in a real gas have large molecules (their volume is not negligible).
- Real gas molecules have intermolecular forces
What are the conditions necessary for a gas to approach ideal gas behaviour?
Very high temperatures and very low pressures
At a very high temperature and a very low pressure, particles have high kinetic energy and are far apart. They have negligible intermolecular forces and particles occupy negligible volume compared with the volume of the container.
Explain the limitations of the ideal gas behaviour
The difference between an ideal gas and a real gas are especially noticeable at very high pressures and very low temperatures. Under these conditions:
Molecules are close to each other so volume of the molecules is not negligible compared with the volume of the container.There are Van der Waals forces of attractions between molecules. These attractive forces pull the molecules towards each other and away from the walls of the container
Properties of ionic compounds
- High melting points because a lot of energy is required to break the strong
forces of attraction between positve ions and negative ions. - The structure is rigid and brittle.
- They are usually soluble in aqueous solvents.
- In solid state, they are non-conductors of electricity because ions are in fixed
positions. When molten or in aqueous solution they conduct electricity because
ions are free to move form one place to another
Properties of a crystalline solid which is simple molecular
- Low melting and boiling points because the Van der Waals’forces require very
little energy to break because they are weak. - Non conductor of electricity in any state becaues no charged particles are
present. - Low solubility in water because iodine molecules can not form hydrogen bonds
with water
i.e iodine
Properties of carbon fullerene
- Low sublimation point turns directly from solid to gas when heated at 600oC
because of weak van der Waals’ forces between its molecules. - Soft because it requires very little energy to overcome weak van der Waals’
forces. - It is a poor conductor of electricity compared with graphite because the extent
of electron delocalisation is lower. - it is more reactive compare with graphite or diamond (reacts with H2, O2, F2, Cl2
and Br2) because of the relatively higher electron density in certain parts of the
molecules
Properties of a carbon nanotube
- They have very high tensile strength when a force is applied along the long axis
of the cylinder. They can be up to 100 times stronger than steel of the same
thickness. - They have very high electrical conductivity along the long axis of the cylinder
because some of the electrons are delocalised and can move along the cylinder
when a voltage is applied. They are superconductors at low temperatures. - They have vey high melting points (about 3500oC) because of strong covalent
bonds thoughout the structure. - Good heat conductance.
- Multi-walled nanotubes exist, where several concentric tubes lie within each
other. The inner tubes can rotate and slide within the outer tube with negligible
friction.
Properties of a crystalline solid which is a giant molecular
- It is hard due to very strong covalent bonds.
- Has a high melting and boiling point because the very strong silicon-oxygen
covalent bonds have to be broken throughout the structure before melting
occurs. - It does not conduct electricity. There are no delocalised electrons and no ions.
- It is insoluble in water and organic solvents. There are no possible attractions
which could occur between solvent molecules and silicon or oxygen atoms
resulting in overcoming the covalent bonds in the structure
Properties of graphene
- Graphene is extremely strong for its mass. (One square hammock made of
graphene could support a 4kg cat but would weigh only as much as the cat’s
whisker.) - Graphene conducts electricity and heat much better than graphite.
- Graphene is the most chemically reactive form of carbon. Single sheets if
graphene burn at very low temperatures and are much more reactive than
graphite.
Allotropes of carbon
Graphene
nanotube
fullerene
diamond
graphite
Factors affecting the strength of metallic bonds
- Number of protons/strength of nuclear attraction.
-The more the protons the stronger the force of attraction between the positive ions and the delocalised electrons - NUmber of delocalised electrons per atoms-the more the stronger
- Size of atoms-the smaller the stronger
Advantages of recycling
- less wastes.
- Cheaper than extracting the metals form
ores. - Saves energy and ores