Chemistry Paper 1

What are the rules for the anode in aqueous electrolysis

attract negative ions, is it a halogen; if no then oxygen is produced

What are the rules for the cathode in aqueous electrolysis

attract positive ions, is it less reactive than hydrogen;whatever is less reactive is formed

what is the rule that applies for molten electrolysis

OPPOSITES ATTRACT

Which electrode has electrons before the arrow in half equations

Cathode as CaRGe (cathode reduction gain electrons)

what are the 2 irregular half equations

2O²- →O2+4e-

2(halogen)→(halogen)2+2e-

During molten electrolysis what is the important acrostic

Oxidation

Is

Loss

Reduction

Is

Gain

define an ore

a naturally occurring rock containing enough metal or metal compounds to make it economically worthwhile to extract

What is dissolved when acids are dissolved in water

Hydrogen ions

What is dissolved when alkalis are dissolved in water

hydroxide ions

What are the characteristics of acids

more H ions lower the pH, factor of /10 for every pH you go up

What is a strong acid

higher concentration of H ions so fully ionises when dissolved in water (weak acids are opposite)

What is a concentrated acid

Has lots of acid and small volumes of water

What are the 4 key equations to remember

metal+acid→salt+hydrogen

metal oxide+acid→salt+water

metal hydroxide+acid→salt+water

metal carbonate+acid→salt+water+CO2

What are the key equations (there is 10)

Relative formula mass

n=m/mr

c=n/v

volume of gas=nx24

c(g/dm³)=c(mol/dm³)xMr

percentage yield=actual/theoretical x100

atom economy=(Mr of desired product/totalMr of all reactants)x100

Rf=distance travelled by substance/distance travelled by solvent

Energy change=bonds broken-bonds formed

percentage mass=(Ar x number of atoms/Mr of compound)x100

What are some of the characteristics of giant covalent structures

String covalent bonds between atoms, high melting and boiling point, solid at room temperature

What are the characteristics of Large covalent molecules (polymers)

many repeating unites joined together by covalent bonds to create a chain, long molecules, strong covalent bonds between atoms but separate chains are held together by weak intermolecular forces (stronger than in small molecules), mid boiling points (more than small molecules less than giant structures), solid at room temperature, stronger forces than smaller molecules

What are the characteristics of Large covalent molecules (polymers)

many repeating unites joined together by covalent bonds to create a chain, long molecules, strong covalent bonds between atoms but separate chains are held together by weak intermolecular forces (stronger than in small molecules), mid boiling points (more than small molecules less than giant structures), solid at room temperature, stronger forces than smaller molecules

What is the structure of an atom and their charge and mass

Nucleus-contains protons and neutrons

Protons-have a positive charge (+1) and a relative atomic mass of 1

Neutrons-have no charge and a relative atomic mass of 1

Electrons-have a negative charge (-1) and a very small mass

What are the calculation to figure out some parts of the atomic structure

Protons-number of protons equals the atomic number

Electrons-in a neutral atom, the number of electrons equals the number of protons

Mass number-total number of protons and neutrons

Neutrons-subtract the atomic number from the mass number

What is the definition of an isotope

Atoms of the same element that have a different number of neutrons. This means they have the same number of protons and electrons, so their chemical properties are similar, but their masses differ.

What is an ion

Atoms that have gained or lost electrons, resulting in a net electrical charge

What is a cation

Positively charged ions formed by losing electrons

What is an anion

Negatively charged ions formed by gaining electrons

In what order were the subatomic particles found and who discovered them

Electrons-J.J. Thompson (1897)

Protons-Ernest Rutherford (1919)

Neutrons-James Chadwick (1932)

What are the different atomic structure models

Dalton model (John Dalton)-Atoms are tiny, indivisible, solid spheres. Atoms of the same element are identical, and different elements have different atoms

Plum pudding model (J.J. Thompson)-A ball of positive charge with negative electrons embedded in it

Nuclear model (Ernest Rutherford)-A small, dense, positively charged nucleus at the center, with electrons orbiting it. This model was developed after the "gold foil" experiment, which showed that most of the atom is empty space

Bohr model (Niels Bohr)-An improvement on the nuclear model, it places electrons in fixed orbits or energy levels around the nucleus

Modern model-The currently accepted model, based on Bohr's work, where a nucleus containing protons and neutrons is surrounded by electrons in shells. The number of particles can be calculated using the atomic and mass numbers

What are all the forms of separation and what are they used for

Filtration-Used to separate an insoluble solid form a liquid

Evaporation-Used to separate a soluble solid from a solvent (like salt from water)

Simple distillation-Used to separate a solvent from a soluble solid or to separate two liquids with significantly different boiling points

Fractional Distillation-Used to separate a mixture of liquids with similar boiling points

Crystallisation-Used to obtain a pure solid from a solution

Chromatography-Used to separate different colour dyes in a mixture

Separating funnel-Used to separate liquids that do not mix

All information about the groups in the periodic table

Definition-Vertical columns in the periodic table

Key feature-Elements in the same group have the same number of electrons in their outermost shell, also called valence electrons

Significance-This results in elements within the same group having similar chemical properties and reactivity

All information about periods in the periodic table

Definition-Horizontal rows in the periodic table

Key feature-Elements in the same period have the same number of electron shells

Significance-The properties of elements change predictably as you move across a period, from left to right

How are the elements arranged

They are arranged in order of increasing atomic number it also means the layout allows for predictions of an element’s properties based on its position

What is the reactivity of the group 1 elements (alkali metals)

Increased as you go down the group because the outer electron is easier to lose as it is further from the nucleus and is shielded by more inner electrons.

Examples:Lithium reacts slowly, while potassium reacts very vigorously, melting and burning with a lilac flame

What is the reactions with water of the group 1 elements (alkali metals)

Lithium floats and fizzes gently, sodium melts into a ball and fizzes more strongly, and potassium melts, moved rapidly, and it’s hydrogen gas ignites, causing a lilac flame

What is the reactivity of the group 7 elements (halogens)

Decreases as you go down the group as it is more difficult to lose an electron with fluorine being the most reactive and iodine as the least reactive

What are the physical properties of the group 7 elements (alkali metals)

They exist as diatomic molecules (F2,Cl2,Br2,I2) their boiling point increase down the group as the molecules get larger and have stronger intermolecular forces

What is the reactivity of the group 0 elements (noble gases)

They are unreactive as they have a full outer shell of electrons so they don’t need to lose, gain or share electrons (they are single atoms)

What are the physical properties of transition metals

They have high melting and boiling points as they have strong metallic bonds (mercury is an exception as it is a liquid at room temperature). They are hard strong metals, they are also great electricity conductors, they aren’t very malleable but are shiny

What are the chemical properties of transition metals

Many transition metals and their compounds are effective catalysts (speed up chemical reactions).Their coloured compounds are Potassium chromate is yellow and potassium permanganate is purple, they can form ions with more than one possible charge, for example iron can form Fe2+ and Fe3+ ions, they are generally less reactive than group 1 metals and react slowly with water or oxygen

All ionic bonding relevant information

Definition:the electrostatic attraction between oppositely charged ions formed by the transfer of electrons.

It happens when a metal atom transfers electrons to a non metal atom (the metal becomes a positive ion and the non metal becomes a negative ion)

Properties of Ionic bonding

Structure:giant ionic lattice structure

High melting and boiling point as it requires a lot of energy to break the string electrostatic forces in the lattice, they are also brittle as strong forces mean the lattice is rigid, but a hard blow can shatter it, it conducts electricity when molten or dissolved in aqueous solution

All covalent bonding relevant information

Definition:A bond formed by the sharing of electron pairs between two atoms

It happens when two or more non metal atoms share electrons so that each atom has a full outer shell

Properties of Covalent bonds

Structure:Can be simple molecular or giant covalent structures e.g. diamonds and graphite

Simple molecular:Low melting and boiling points due to weak forces between molecules, they are poor conductors of electricity as there are no ions or delocalised electrons

Giant covalent:very high melting and boiling points as many strong covalent bonds need to be broken, poor conductors of electricity expect graphite

All metallic bonding relevant information

Definition:The electrostatic attraction between a lattice of positive metal ions and a sea of delocalised electrons

It happens in a metal, the outer electrons are not associated with a single atom but are free to move throughout the entire structure

Properties of metallic bonds

Structure:A giant lattice structure

High melting and boiling points as they have strong electrostatic forces between the positive ions and delocalised electrons, the delocalised electron is free to move and carry the charge through the lattice structure so does conduct electricity, layers of atoms can slide past eachother

How is the reactivity series used

Displacement reactions:A more reactive metal will displace a less reactive metal from its compound

Reactions with acid:Metals above hydrogen in the series will react with acids to produce hydrogen gas

Reactions with water:Metals at the top of the series react with water, the reaction rate decreases as you go down the series

All relevant information for acid+metals

Products:salt and hydrogen gas

Reactivity:the metal must be more reactive than hydrogen in the reactivity series for the reaction to occur

Chemical process:This is a redox reaction, where the metal is oxidised (lose electrons) and hydrogen ions are reduced (gain electrons)

All relevant information for acid+base (neutralisation)

Products:Salt and water

Chemical process:A neutralisation reaction, where the acids hydrogen ions (H+) react with the bases hydroxide ions (OH-) to form water

Rule:all alkalis are bases but not all bases are alkalis, alkalis are soluble bases that contain hydroxide ions

All relevant information for acid+carbonate

Products:Salt, water and carbon dioxide

Chemical process:a neutralisation reaction

Key terms for electrolysis

Electrolysis:using electricity to split a compound

Electrolyte:a liquid or solution that contains freely moving ions and conducts electricity

Cathode:the negative electrode where positive ions are attracted

Anode:the positive electrode where negative ions are attracted

How electrolysis works

1)An ionic compound must be melted or dissolved in water so its ions are free to move

2)An electric current is passed through the electrolyte, positive ions (cations) move to the negative cathode, and negative ions (anions) move to the positive anode

3)Discharge at the electrodes:

a)Cathode:Positive ions gain electrons to become neutral atoms or molecules, this is a reduction reaction

b)Anode:Negative ions lose electrons to become neutral atoms or molecules, this is an oxidation reaction

4)The result is the decomposition of the ionic compound into it’s constituent elements, which are then discharged at the electrodes

What are the key concepts of oxidation and reduction reactions

Redox reactions:A reaction where both oxidation and reduction occur simultaneously

Oxidation:gain of oxygen but the loss of electrons

Reduction:loss of oxygen but the gain of electrons

All relevant information for exothermic reactions

Definition:Release energy to the surroundings causing the temperature to rise

Bonding:more energy is released when new bonds are formed in the products than is needed to break bonds in the reactants

Examples:Combustion, Neutralisation reactions, Many oxidation reactions

Everyday uses:Self-heating cans and hand warmers

All relevant information for endothermic reactions

Definition:take in energy from the surroundings causing the temperature to fall

Bonding:more energy absorbed to break bonds in the reactants than is released when new bonds are formed in the products

Examples:thermal decomposition, reaction of citric acid with hydrogen carbonate

Everyday uses:sport injury packs

Key concepts of energy hanged during chemical reactions

Energy conservation:energy is conserved in chemical reactions, meaning the total energy in the universe before and after a reaction is the same

Reaction profiles:Diagrams that show the relative energy of reactants, products, activation energy, and the overall change of a reaction

Bond breaking/making:energy is supplied to break new bonds and energy is released when new bonds are made

What is the definition of activation energy

the minimum amount of energy required for a chemical reaction to take place. If a catalyst is added it speeds up the reaction lowering the activation energy as it provides an alternate pathway

Explain the titration practical

1-using a pipette measure out 25cm³ of (what’s in the q or first reactant) into a conical flask-place on a white tile

2-add a few drops of phenolphthaleine

3-fill the burette with dilute hydrochloric acid and take the start reading from the meniscus

4-Add HCl acid from the burette to the sodium hydroxide in the conical flask, swirling the contents at all times

5-add the acid drop wise near the end point until there is a permanent colour change

6-measure the volume added

7-repeat until 3 results within 0.1cm³ of eachother and calculate a mean