4th Form Flashcards
Why do high surface area increase rate of reaction?
More of the solid is exposed to the other particles
So there are more particles per unit volume
So the collision frequency is higher
So there are more successful collisions per unit time
Why does a higher concentration increase rate of reaction?
There are more particles per unit volume
So the collision frequency is higher
So there are more successful collisions per unit time
Why does a higher temp increase rate of reaction?
The particles have more kinetic energy
So the percentage of collisions with energy above activation energy is higher
So there are more successful collisions per unit time
Why does a catalyst increase rate of reaction?
They provide an alternative route with a lower activation energy
So the percentage of collisions with energy above activation energy is higher
So there are more successful collisions per unit time
Define covalent bonding
The electrostatic attraction between protons in two nuclei and a shared pair of electrons between them
Why do simple molecular covalent substances boil easily?
Although simple molecules contain very strong covalent bonds, there are also weak intermolecular forces (IMFs) between the molecules.
When simple molecular substances boil, it’s the weak IMFs which break
Why can a simple molecular substance not condunt electricity?
Electrical conductivity requires charged particles that can move freely
But in a simple molecular substance, there aren’t any charged particles
Why does diamond have a high melting point?
Covalent bonds are very strong
There are lots of bonds in the giant lattice
Lots of energy is required to break all the bond
Why can diamond not conduct electricity, but graphite can, since they are both types of carbon?
Diamond cannot conduct electricity, as there are no free moving charged particles, as all the electrons are stuck inside an atom or a bond. Graphite has free moving charged particles between the layers, so it can.
Name the structure and essential properties of an ionic bond.
Giant lattice
High mp/bp
Insulator when solid
Conductor when liquid
Conductor when in an aqeous solution
Name the structure and essential properties of a convalent bond.
Simple molecular substance
Low mp/bp
insulator
Name the structure and essential properties of a metallic bond
Giant lattice
High mp/bp
Conductor
What happens when halogens (group 7) react with metals?
Form ionic compounds
Why is it harder for halogens lower down the group to bond?
Atoms have more electron shells
The extra electron is further from the nucleus
So its attraction to the nucleus is weaker
(Harder for the atom to pull in an extra electron.)
Chlorine test
Damp blue litmus paper → turns white
As you go down in groups halogens get ……. …………..
As you go down in groups noble gases get ……. …………
Less reactive
More reactive
How to calculate RFM?
By adding the relative atomic masses (RAMs) of the atoms or ions
How to find percentage by mass of an element in a compound?
(Mass of element/RFM)x100
equation for moles
mass/RFM
table to calculate moles:
Element 1 Element 2
Mass:
RFM:
Moles:
Ratio:
How to calculate mole ratio in a formula?
Only look at big numbers: eg
2Na+S
If you were asked to find the mole ratio of Na to S, it would be 2:1 respectivly
Describe a metallic structure
A sea of delocalised electrons
A lattice of positive metal ions
How can metals conduct electricity?
Delocalised electrons can pass through the lattice
Define metallic bonding
The electrostatic attraction between the positive metal ions and the negative delcalised electrons.
Table of reactivity
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Zinc
Iron
Copper
Structure of Diamond
Every carbon makes 4 covalent bonds
Tetrahedral
Structure of graphite
Layers of Carbon
Every carbon makes 3 covalent bonds
Weak inter molecular forces between layers
Delocalised electrons between layers
Isotope definition
Atoms of the same element with different numbers of neutrons
What colour change occurs when copper carbonate is heated
Green to black
Discuss the differences between diamond and graphite. Refer to bonding,structure, electrical conductivity, and hardness.
Diamond (structure):
Tetrahedral structure
Graphite (structure)
Hexagonal structure made up of layers
Diamond (conductivity)
Diamond does not conduct electricity (1)
Because it has no delocalised electrons (1)
Graphite (hardness)
Graphite is malleable (1)
Because it has layers that can slide over each other (1)
Why does C60 fullerene have a much lower melting point than diamond and graphite
C60 fullerene has weak intermolecular forces
which are easily overcome
whereas diamond has strong covalent bonds
which require lots of energy to overcome
What obervations would you see when magnesium reacts to form magnesium oxide
bright white light
effervesence
chromatography experiment
- Draw a start line in pencil near the bottom of the paper
- Place the samples on the start line
- Put the paper in the beaker with the start line above the water level
- Mark the solvent front
HCL Formula, name of Salt, Anion formula
HCL, Chloride Cl-
Nitic Formula, name of salt, and Anion Formula
HNO3, Nitrate, No3-
Sulphuric formula, name of Salt, and Anion formula
H2So4, Sulphate, So4-
Ethanoic formula, name of salt and Anion formula
CH3COOH, Ethanate, Ch3COO
Sodium Hydroxide
NaOh
Potassium hydroxide
KOH
Ammonium Hydroxide
NH4OH
Molecular and structural formula of Methane
CH4, CH4
Molecular and structural formula of Ethane
C2H6, CH3CH3
Propane molecular formula and structural formula
C3H8, CH3CH2CH3
Butane Molecular formula and structural formula
C4H10,CH3CH2CH2CH3
Pentane
C5H12,CH3CH2CH2CH2CH3
Define homologous series
a collection of compounds with the same general formula that only changes with the Carbon chain lengh.
List the order for Cracking
refinery gases
gasoline
kerosene
diesel
bitumen
fuel oil
What is the catalyist in cracking reactions
aluminium Dioxide
What temperature is cracking performed at
650 degrees C
Give the general formula for alkanes
CnH2n
use of kerosene
jet fuel
use of bitumen
road surfacing
give a reason for the importance of a catalytic cracking reaction
shorter chain molecules are in higher demand (eg for petrol)
unsautrated in alkenes meaning
they contain a double carbon bond
test for unsaturation
bromine water turns from orange to colorless
Ammonium test
Add NaOH
Damp red litmus paper will turn blue
