PAPER 1 GCSE Flashcards
Arrangement of solids
Particles are close together and regularly packed
Movement of solids
Particles vibrate around a fixed point
Energy of solids
Particles have less kinetic energy than both liquids and gasses
Arrangement of liquid
Particles are close together but irregular.
Movement of liquids
Particles are free to move
Energy of liquids
Particles have less kinetic energy than gasses but more than solids
Arrangement of gas
Particles are far apart and there are no forces between them
Movement of gas
Particles are free to move
Energy of gas
Particles have more kinetic energy than liquids and solids.
Melting
When a solid is heated, the energy makes the particles vibrate fast enough so that the forces of attraction between the particles break
Freezing
When a liquid is cooled, the particles move slow enough so that the forces of attraction between them will hold them into a solid
Boiling
When a liquid is heated strongly, the energy makes the particles move fast enough so that all forces of attraction are broken
Condensing
When a gas is cooled, the particles move slow enough so that the forces of attraction between them will hold them as a liquid
understand how the results of experiments involving the dilution of coloured solutions and diffusion of gases can be explained
Diffusion is the spreading out of particles in a gas or liquid. There is a net movement of particles from areas of high concentration to areas of low concentration until a uniform concentration is achieved
Solvent
the liquid in which it dissolves
Solute
the substance that dissolves
Solution
The liquid that forms after dissolving
Saturated solution
solution into which no more solute can be dissolved
What is the atom
An atom is the smallest part of an element.
Molecule
molecule is made of a fixed number of atoms covalently bonded together
Atomic number
The number of protons in an atom
Mass number
The number of protons and neutrons in an atom
Relative atomic mass
The average mass of an atom compared to 1/12th the mass of carbon-12
Isotopes
Atoms of the same element (same number of protons) but with a different number of neutrons
What is a mol
The mass of 1 mole of a substance is the relative formula mass (Mr) of the substance in grams
What is yield
Yield is how much product you get from a chemical reaction
Theoretical yield
the amount of product that you would expect to get
How to calculate the actual yield
Actual amount / theoretical amount
Finding the formula of a metal oxide experimentally
reacting a metal with oxygen and recording the mass changes.
Finding the formula of a salt containing water of crystallisation
When some substances crystallise from solution, water becomes chemically bound up with the salt. This is called water of crystallisation
The difference of mass before and after heating is the mass of the water lost
What is the empirical formula
shows the simplest whole-number ratio between atoms/ions in a compound
What is the molecular formula
shows the actual number of atoms of each type of element in a molecule.
What is a covalent bond
ESFOA between the nuclei and the shared pairs of electrons
How is covalent bond formed
A covalent bond is formed between two non - metal atoms by sharing a pair of electrons in order to fill the outer shell
Why do simple molecular substances have a low boiling point
between the molecules are weak intermolecular forces of attraction that require little energy to break
explain why the melting and boiling points of substances with simple molecular structures increase, in general, with increasing relative molecular mass
because larger molecules (molecules with more mass) have more forces of attraction between them. These forces, although weak, must be overcome if the substance is to boil, and larger molecules have more attractions which must be overcome.
why substances with giant covalent structures are solids with high melting and boiling points
it is a giant covalent structure with many strong covalent bonds that require a lot of energy to break.
Why is diamond hard
is a giant covalent structure with many strong covalent bonds that require a lot of energy to break
Why can graphite conduct electricity
because the delocalised electrons are free to move
each carbon atom has one electron not involved in a covalent bond, and these electrons form a sea of delocalised electrons between the layers
Why is graphite soft and slippery
Each layer is a giant structure, with weak forces of attraction between the layers. These layers can easily slide over each other
Why do covalent compounds usually not conduct electricity
Electric current is a flow of charged particles that can move.
Covalent compounds do not conduct electricity.
Percentage of nitrogen in air
78 percentage
Percentage of oxygen in air
21 percent
Percentage of argon in air
0.9
Percentage of CO2 in air
0.04
How to use carbon to determine the percentage of oxygen in air
The copper is in excess and uses up the oxygen to form copper oxide (CuO).
All the oxygen in the air is therefore used up, and so the volume of the air decreases by about 20% (the percentage of oxygen in air).
How to use iron to determine the percentage of oxygen in air
The iron reacts with the oxygen in the air (rusting).
As long as the iron and water are in excess, the total volume of air enclosed by the apparatus decreases by about a fifth (20%) over several days.
How to use phosphorus to determine the percentage of oxygen in air
The phosphorus is lit with a hot wire.
It reacts with the oxygen in the air and causes the water level in the bell jar to rise by about 20%.
How does magnesium react with oxygen (combustion)
producing a bright white flame leaving behind a white ash of magnesium oxid
How does hydrogen react with oxygen (combustion)
in an explosive reaction. This is the basis of the ‘squeak pop’ test for hydrogen in test tube. With larger quantities of hydrogen this explosion can be dangerous.
How does sulphur react with oxygen (combustion)
reacts with oxygen producing a blue flame
What happens if you heat metal carbonates
On heating metal carbonates thermal decompose into metal oxides and carbon dioxide.
CO2 is a greenhouse gas which
absorbs infra-red radiation and therefore warms the atmosphere. This leads to global warming.
This may cause climate change.
Test for hydrogen
Use a lit splint
gas pops
Test for oxygen
use a glowing splint
relights
Test for CO2
Bubble the gas through limewater
limewater turns cloudy
Test for ammonia
Turns damp red litmus paper blue
Test for chlorine
Bleaches moist litmus paper
How to carry out a flame test
A platinum or nichrome wire is dipped into hydrochloric acid to remove any impurities.
The wire is dipped into the salt being tested
The wire and salt are held in a (roaring) bunsen burner flame.
The colour is observed
Lithium flame colour
red
Sodium flame colour
yellow
Potassium flame colour
lilac
Calcium flame colour
orange - red
Copper II flame colour
blue - green
Describe tests for the cation NH4+ (ammonium)
add sodium hydroxide and warm
will turn damp litmus paper blue
Describe tests for the cations Cu2+, Fe2+ and Fe3+ (copper, iron)
First, add sodium hydroxide (NaOH), then observe the colour:
blue precipitate forms
green precipitate forms
brown precipitate forms
Describe tests for Halide ions (Cl–, Br– and I–)
add nitric acid to remove impurities then add silver nitrate solution Chloride - white precipitate Bromide - cream precipitate Iodine - yellow precipitate
Describe tests for anions: Sulfate ions (SO42–)
Add hydrochloric acid to remove impurities
add barium chloride solution
white precipitate will form
Describe tests for anions: Carbonate ions (CO32-)
add hydrochloric acid
fizzing will occur
describe a test for the presence of water using anhydrous copper(II) sulfate
Add anhydrous copper (II) sulfate (CuSO4) to a sample.
If water is present the anhydrous copper (II) sulfate will change from white to blue.
how can the rate of reaction be measured
The rate of a chemical reaction can be measured either by how quickly reactants are used up or how quickly the products are formed.
if surface area increases
rate of reaction increases
increases surfaces for collisions
more frequent successful collisions
if concentration increases
rate of reaction increases
increases number of particles in a given area
more frequent successful collisions
if temperature increases
rate of reaction increases
particles have more energy so move quicker
more particles have the required activation energy
more frequent successful collisions
what is a catalyst
a substances that increases the rate of reaction but remains chemically unchanged at the end by providing an alternate pathway with lower activation energy
what is crude oil
a mixture of hydrocarbons
how does fractional distillation work
Crude oil is separated by fractional distillation.
Crude oil is heated and the oil evaporates.
It then goes into the tower. As the vapours rise up the tower the temperature falls.
Different sized fractions condense at different heights because they have different boiling points.
Smaller molecules condense high up the tower. Larger molecules condense low down in the tower.
The fractions are collected
refinery oil
bottled gas
gasoline
fuel for cars
kerosene
fuel for planes
diesel oil
fuel for lorries
fuel oil
fuel for ships
bitumen
road surfacing
The boiling point increases as
the number of carbon atoms (chain length) increases.
The viscosity increases as
the number of carbon atoms (chain length) increases.
the darker in colour that fraction is
The greater the number of carbon atoms (chain length)
what is a fuel
a substance that when burned releases heat energy
Complete Combustion happens when
there is enough oxygen available, producing carbon dioxide (CO2) and water (H2O)
Incomplete Combustion happens when
there is not enough oxygen available, with possible products being carbon monoxide (CO), carbon (C, soot), carbon dioxide (CO2) and water (H2O)
Carbon monoxide is poisonous because
it reduces the capacity of the blood to carry oxygen.
nitrogen oxides are produced when
in car engines the temperature reached is high enough to allow nitrogen and oxygen in the air to react
sulfur dioxides are produced when
some impurities in hydrocarbon fuels combust
how sulfur dioxide and oxides of nitrogen oxides contribute to acid rain
sulfue dioxide and nitrogen oxides can react with water to make acids
Acids formed in the atmosphere can fall as acid rain. killing trees and fish in lakes.
the acid rain also corrodes limestone buildings and marble statues since these are both made of calcium carbonate
some metals such as iron are also attacked by acid rain.
cracking is
the thermal decomposition of long-chain alkanes into shorter-chain alkanes and alkenes:
the conditions of cracking
600 - 700 degrees
catalyst - silica/alumina
why cracking is necessary
Crude oil contains a surplus long chains.
Shorter chain hydrocarbons are in greater demand, e.g. petrol.
Cracking also produces alkenes which are used in making polymers and ethanol.
the general formula for alkanes
CnH2n+2
saturated hydrocarbons
A molecule containing only single bonds between carbon atoms (alkanes)
Alkanes react with bromine (halogens)
In the presence of UV light, e.g. sunlight.
A hydrogen atom in the alkane is replaced by a bromine atom.
This is known as substitution.
methylbromine + hydrogen bromide
