March Mocks Flashcards
Definition of Element?
A substance made up of atoms that all contain the same number of protons (one type of atom) and cannot be split into anything simpler.
What is a Pure Substance?
Contains only one substance, with no other substances mixed together
Why does a Mixture’s boiling point vary?
Has a range of melting and boiling points as they consist of different substances that melt or boil at different temperatures
On a Chromotography Paper, would a more soluble dye be higher up or lower down on the paper?
Higher Up
Rf equation?
Rf value = distance moved by compound ÷ distance moved by solvent
Definition of an Atom?
The smallest particle of an element that consists of electrons surrounding a nucleus that contains protons and neutrons.
Definition of a Molecule?
A cluster of non metal atoms that are chemically bonded together
RAM?
Weighted average mass of one atom of an element, taking into account the abundances of all the isotopes of that element.
Ar equation
(% of Isotope 1 x mass of Isotope 1) + (% of isotope 2 x mass of isotope 2)/100
Definition of Simple Molecular Structure?
Consists of molecules in which the atoms are joined by strong covalent bonds.
Melting and Boiling Point of Simple compounds in relation to Molecular Mass:
As the relative molecular mass of a substance increases, the melting and boiling point will increase as well (positive correlation).
An increase in the relative molecular mass of a substance means that there are more covalent bonds in the structure, so there are more intermolecular forces of attraction that need to be broken down.
So larger amounts of heat energy are needed to overcome these forces, causing the compound to have a higher melting and boiling point
Melting and Boiling Point of Simple compounds in relation to Molecular Mass:
The relative molecular mass of a substance and the melting and boiling point are directly Proportional
An increase in the relative molecular mass of a substance means that there are more covalent bonds in the structure, so there are more intermolecular forces of attraction that need to be broken down.
So larger amounts of heat energy are needed to overcome these forces, causing the compound to have a higher melting and boiling point
Giant Covalent Structure
Non-metal atoms
joined to adjacent atoms by covalent bonds
forms a giant lattice structure.
Allotropes
Different atomic, molecular arrangements of the same element in the same physical state.
Properties of Carbon?
Hard
Each carbon atom is joined to four other carbon atoms, forming a giant covalent structure.
Strong covalent bonds are difficult to break.
High Melting and Boiling Point
Giant Covalent Structure so there are many strong covalent bonds that needs to be broken down.
Large amounts of heat energy is needed to overcome forces and break down bonds.
Does not Conduct Electricity
All four valence (outer-shell) electrons are used in covalent bonds so there are no delocalised electrons that are mobile to conduct electricity
Uses:
Cutting Tools
Jewellery
Properties of Graphite
Properties:
Soft and Slippery
Graphite is made up of two-dimensional layers of carbon atoms, which are held by weak van der Waal’s forces, lie on top of each other.
Forces of attraction between the layers are weak so the layers easily slide over one another and can easily be separated.
High Melting and Boiling Point
Within each layer, each carbon atom forms strong covalent bonds with three other carbon atoms in a giant covalent structure so there are many strong covalent bonds that needs to be broken down
Large amounts of heat energy is needed to overcome forces and break down bonds.
Conducts Electricity
Only three valence electrons are used in forming covalent bonds
Fourth electron is delocalised between the layers and free to move parallel to the layers to conduct an electric charge.
Uses:
Lubricant
Electrodes for Electrolysis
Properties of Fullerene?
Soft
Each carbon atom is joined to only three other carbon atoms so there are weak intermolecular forces of attraction between molecules.
Intermolecular bonds can be broken down easily making it soft.
Low Melting and Boiling Point
Each carbon atom is joined to only three other carbon atoms.
This means that there are weak intermolecular forces of attraction between molecules.
So small amounts of heat energy is needed to overcome forces and break down bonds.
Conducts Electricity
Only three valence electrons are used in forming covalent bonds.
Fourth electron is delocalised and is free to move to conduct an electric charge.
Uses:
Drug Delivery System in the Body (Nanotubes)
Lubricant
Catalyst
Explain the bonding of metallics?
Metal atoms are held strongly to each other by metallic bonding.
In the metal lattice, the atoms lose their valence electrons and become positively charged.
The valence electrons no longer belong to any metal atom and are said to be delocalised.
They move freely between the metal ions like a sea of electrons.
Electrolyte?
A liquid that conducts electricity.
How to conduct an experiment of electrolysis of lead bromide?
Add Lead (II) Bromide into a beaker and heat so it will turn molten, allowing ions to be free to move to conduct an electric charge.
Add two graphite rods as the electrodes and connect this to a power pack or battery.
Turn on power pack or battery and allow electrolysis to take place.
Negative bromide ions move to the positive electrode (anode) and lose two electrons to form bromine molecules. There is bubbling at the anode as brown bromine gas is given off.
Positive lead ions move to the negative electrode (cathode) and gain electrons to form a grey lead metal that deposits on the surface of the electrode.
Ionic Half equation for Oxygen?
2H2O - 4e- –> O2 + 4H+
Electrolysis of Aqueous Solutions?
Add Aqueous solution into a beaker.
Add two graphite rods as the electrodes and connect this to a power pack or battery.
Turn on power pack or battery and allow electrolysis to take place.
How to find the products of Aqueous Electrolysis
An investigation into the products formed at each electrode can be done:
If a solid forms around the electrode, the metal ions have been deposited. Colour can give away what metal.
If the gas produced at the cathode burns with a ‘pop’ when a sample is lit with a lighted splint. This shows that the gas is hydrogen.
If the gas produced at the anode relights a glowing splint dipped into a sample of the gas. This shows that the gas is oxygen.
Exothermic Reaction definition?
Reaction in which thermal energy is given out to the surroundings
Delta H = -
Examples of an Exothermic Reaction?
Burning
Neutralisation
Reaction between Water and Calcium Oxide
Endothermic Reaction definition?
Reaction in which thermal energy is taken from the surroundings
Examples of Endothermic Reactions?
Electrolysis
Thermal Decomposition of Copper Carbonate
Reaction between Ethanoic acid and Sodium Carbonate
How do we know something is endothermic
If more energy is absorbed than it releases, this reaction is endothermic
More energy is required to break the bonds than make the bonds
Energy Change equation?
LHS - RHS
Calorimetry experiment for neutralisation, dissolving and neutralisation?
Using a measuring cylinder, place 25 cm3 of solution 1 into a polystyrene cup
Measure and record the temperature of solution 1
Add a measured amount of reactant (solid for dissolving, solution 2 for displacement and neutralisation) into the polystyrene cup and stir the mixture
Measure and record the highest temperature reached by the mixture
Calorimetry experiment for Combustion?
Using a measuring cylinder, put 100 cm3 of water into a copper can
Measure and record the initial temperature of the water
Fill the spirit burner with test substance and measure and record its mass
Place the burner under the copper can and light the wick
Stir the water constantly with the thermometer and continue heating until the spirit burner burns out
Measure and record the highest temperature of the water
What happens when acids react in water?
they produce hydrogen ions (H+).
These H+ ions make the aqueous solution acidic.
Dissociation of HCL
HCl (aq) → H+ (aq) + Cl– (aq)
What are acids usually produced from?
Metal Oxides
What happens with Weak acids?
ionizes partially/incompletely in water. In this case they form an equilibrium between the acid and the ions in solution.
Acid + Metal Carbonate
Acid + Metal Carbonate → Salt + Carbon Dioxide + Water
Metal Oxide + Acid?
Salt + Water
Metal Hydroxide + Acid?
Salt + Water
Ammonia + Salt
Ammonium Salt + Water
Are Metal Oxides, Ammonia and Metal Hydroxides Insoluble or Soluble in Water?
Yes
Describe an experiment to prepare a pure, dry sample of a soluble salt, starting from an insoluble reactant
Add dilute acid into a beaker and heat using a bunsen burner flame
Add the insoluble base, a little at a time, to the warm dilute acid and stir until the base is in excess
Filter the mixture into an evaporating basin to remove the excess base
Heat the solution to evaporate water and to make the solution saturated.
Check the solution is saturated by dipping a cold, glass rod to the solution and seeing if crystals form on the end.
Leave the filtrate in a warm place to dry and crystallise
Decant excess solution
Blot crystals dry
How to make an Insoluble Salt from Soluble Reactants?
Dissolve soluble salts in water and mix together using a stirring rod in a beaker
Filter to remove precipitate from mixture
Wash filtrate with water to remove traces of other solutions
Leave in an oven to dry
How to make Copper Sulfate?
Add dilute sulfuric acid into a beaker and heat using a bunsen burner flame
Add copper (II) oxide (insoluble base), a little at a time to the warm dilute sulfuric acid and stir until the copper (II) oxide is in excess (stops disappearing)
Filter the mixture into an evaporating basin to remove the excess copper (II) oxide
Leave the filtrate in a warm place to dry and crystallize
Decant excess solution
Blot crystals dry
How to make Lead Sulfate
Dissolve Lead (II) Nitrate and Potassium Sulfate in water and mix together using a stirring rod in a beaker
Filter to remove precipitate from mixture
Wash residue with water to remove traces of potassium nitrate solution
Leave in an oven to dry
Characteristics of Lithium reacting with Water?
Reaction slower than Na
H2 gas
Lithium’s melting point is higher and heat isn’t produced quickly, so the lithium doesn’t melt
Observations when Na reacts with Water?
Melts around in a tiny ball that dashes around the surface
Floats on Water because its less dense
Melts because Sodium has a low melting point and a lot of heat is made in this reaction
Hydrogen is evolved which causes the ball of sodium to move around the surface of the water
What happens when Rubidium is reacted with Water?
Explodes with Sparks
What happens when Caesium is reacted with Water?
Violent explosion due to rapid production of heat and Hydrogen
Trend of Reactivity in Group 1?
Reactivity of group 1 metals increases as you go down the group.
Each outer shell contains only one electron, when group 1 metals react, they will lose one outer electron to get a full outer shell of electrons.
As you go down group 1, the number of shells of electrons increases by 1 (period number increases down the periodic table).
This means that the outer electron is further away from the nucleus so there are weaker electrostatic forces of attraction.
This requires less energy to overcome the electrostatic forces of attraction between the negatively charged electron and the positively charged nucleus.
This allows the electron to be lost easily, making it more reactive as you go down the group.
Alchohols
Family of organic (carbon-based) compounds that all contain the -OH group that is responsible for their chemical properties and reactions.
Homologous Series?
Same general formula Same functional group Similar chemical reactions Physical properties show graduations Each member differs in molecular formula from the next by CH2
What does Functional Group mean?
A group of atoms bonded in a specific arrangement that controls the property of the homologous series
Addition Reaction definition?
A reaction in which one molecule combines with another to form a larger molecule with no other products
Incomplete Combustion Chemical Reaction?
CH4 + ½O2 → CO + 2H2O
Results of The Esterification Experiment and what can you do with this?
The distillate can be smelt to check whether an ester has been produced.
Small quantities of ethanoic acid, sulfuric acid and ethanol can also be collected in the process.
To remove acidic impurities, sodium carbonate solution can be added, until the mixture stops fizzing (no more carbon dioxide is evolved).
To remove ethanol, calcium chloride solution can be added.
Polyester unit?
See
Reaction of Ethanedioic acid & 1,2-Ethanediol
See
Reacivity Series
K - Please Na - Stop Li Ca Mg Al C Zn Fe H Cu Ag Au
Uses of Aluminium?
Aeroplane Bodies –> High Strength to Weight
Overhead Power Cables –> Good Conductors of Electricity
Saucepans –> Good Conductors of Heat
Food Cans –> Non-Toxic
Window Frames –> Resistant to Corossion
Uses of Iron?
Car Bodies (strong)
Iron Nails (strong)
Ships, Girders and Bridges (strong)
What is Low Carbon Steel’s use and most important property
Malleable (Car Body Panels)
High Carbon Steels uses and properties?
Cutting Tools –> Hard and Strong
Stainless Steel uses and properties?
Cutlery and Sinks –> Resistant to Corrosion
Why are Alloys hard?
Alloys are often harder than pure metal as they contain atoms of different sizes, which distorts the regular arrangements of atoms
This makes it more difficult for the layers to slide over each other, making it harder and stronger than pure metal (atoms in pure metals are the same size in regular arrangement so can slide over each other easily).
How does the Viscosity vary with Hydrocarbon length?
Viscosity increases with Hydrocarbon Length
How does Hydrocarbon vary with volatillity
As their molecular size increases, hydrocarbon liquids become less volatile
Different Fractions
Refinery Gases –> Bottled Gas
Gasoline –> Car
Kerosene –> Aircraft Fuel
Diesel –> Lorries
Fuel Oil –> Ships for power stations
Bitumen –> Roads
How does Surface Area increase Rate of Reaction?
Increase in the surface area of the marble chip, the rate of reaction will increase
This is because more surface area particles of the marble chips will be exposed to the dilute hydrochloric acid so there will be more frequent and successful collisions, increasing the rate of reaction
How does Concentration increase RoR?
Increase in the concentration of hydrochloric acid, the rate of reaction will increase
This is because there are more particles of hydrochloric acid per volume so there will be more frequent and successful collisions, increasing the rate of reaction
How does Catalyst Increase Rate of Reaction?
The catalyst will provide an alternative pathway requiring lower activation energy so more colliding particles will have the necessary activation energy to react
This will allow more frequent and successful collisions per second, increasing the rate of reaction
Describe the industrial process used to seperate crude oil into fractions
M1 (use) fractional distillation / fractionating column /
fractionating tower
M2 (crude oil) heated / vaporised
M3 column is cooler at top / hotter at the bottom / idea
of temperature gradient
M4 fractions condense/collected at different heights
OWTTE
OR fractions have different boiling point (ranges)
How does increasing pressure increase the rate of reaction?
M1 particles/molecules are closer together
M2 therefore more (successful) collisions per unit time
Equations for the Rate of Reaction?
Amount of reactant used up/ Time Taken
Amount of Product obtained/ Time Taken
Volume of gas produced/ Time Taken
How does an increase in temperature increase the rate of reaction?
Increase in the temperature, the rate of reaction will increase
This is because the particles will have more kinetic energy than the required activation energy, therefore more frequent and successful collisions will occur, increasing the rate of reaction
How does increasing the concentration increase the rate of reaction?
Increase in the concentration of a solution, the rate of reaction will increase
This is because there will be more reactant particles in a given volume, allowing more frequent and successful collisions, increasing the rate of reaction
How does an increase in surface area increase the rate of reaction?
Increase in the surface area of the solid, the rate of reaction will increase.
This is because more surface area particles will be exposed to the other reactant so there will be more frequent and successful collisions, increasing the rate of reaction.
Energy Profile Diagram showing how Catalysts increase the rate of reaction?
See
Energy Profile Diagram with no catalysts?
See
Explain one mistake a student may have made to cause an anomalous result?
timer started too late / stopped too early
OR
thermometer (scale) read incorrectly / timer read
incorrectly
Why are results least accurate at high temperatures?
Time to measure is very short
HEAT LOSS IS GREATEST AT HIGHER TEMPERATURES
Explain another way temperature can increase the rate of reaction?
Particles have energy equal to or greater to the activation energy
More successful collisions per second
What effect does a Catalyst have on Enthalpy Change?
No Change
How does Concentration increase the Rate of Reaction?
More molecules in a given volume
More collisions per unit time
What Separation Technique is used to separate Pure Water from Sea Water?
Simple Distliation
What Separation Technique is used to separate Ethanol from a mixture of ethanol and water?
Fractional Distllilation
Why is it important for the solvent level to be below the spots?
So the spots aren’t dissolved in water
How would a student know when she has added an excess of zinc carbonate ?
When Solid Stops disappearing
Why do Crystals form when the hot saturated solution is cooled (when trying to make hydrated copper sulfate from Copper II Oxide and Sulfuric Acid)?
Crystals are less soluble in water
What separation technique should be used to obtain pure water from a mixture containing salt, sand and water?
Simple Distillation
What method of separation should be used to obtain copper (II) Sulfate from a mixture containing Hydrated Copper Sulfate?
Crystallisation
How should one do the Chromatography experiment?
Place four spots on the paper
Place Paper in a beaker
The solvent level should be below spots
Leave until spots separate
If an Insoluble Solid and a Liquid react, what does it form?
Mixture
If a Soluble Solid and a Liquid react, what does it form?
Solution
What does a Solute mean?
A solute is a substance that can be dissolved by a solvent to create a solution
Benefits of Evaporation?
Quick and Easy
Process of Crystallisation?
Heat it gently with a Water bath
You can Dip a Glass rod into the solution to see if the crystals form
Once we see crystals forming we stop heating it and leave it to cool
Crystals start to form at colder temperatures as solids are less soluble at colder temperatures
Filter out Crystals
Dry Crystals
What does Simple Distillation separation separate?
Separates a liquid from a solution
What does Fractional Distillation separate?
Mixtures of Liquids with Similar Boiling Points
Why is it good to add a lid in a Chromatography experiment?
Stops the Solvent from evaporating
Equation lining moles, 24,000 and volume?
Volume = Moles x 24,000 (cm3)
Explain in terms of bond breaking and bond making, why a reaction may give out energy?
- Breaking bonds is endothermic
- Making Bonds is Exothermic
- More heat energy given out then taken in
Catalyst?
A substance that increases the rate of reaction without being chemically changed.
(no change in mass!!!!!!!!!!!”)
Why does Diamond have a high melting point?
M1 – giant covalent / giant structure/lattice/network
M2 – strong (covalent) bonds/many (covalent)
bonds
M3 – lot of (thermal/heat) energy required
M4 – to break bonds
Covalent Bonding of Ethene?
SAVEMYEXAMS
Explain how two atoms in a chlorine molecule are held together?
Strong attraction between shared pair of electrons and the nuclei of both atoms
Describe the metallic structure of molybdenum?
giant structure of positive ions surrounded by a sea of delocalised electrons
State why Co2 is a gas at room temperature?
Weak forces of attraction between molecules
Why is Cracking carried out?
Greater Supply of Hydrocarbons
High Demand
Alkenes used to make Polymers
Name the Organic Product from the reaction with Methane and Bromine?
Bromomethane
What is a solid product formed from incomplete combustion of propane?
Carbon
What other product is formed when Ethane is cracked into Ethene?
Hydrogen
What is the feature of Saturated compounds?
It contains single bonds ONLY between the Carbon atoms
Definition of Biodegradable?
Can be naturally broken down by microorganisms
Explain how the formula of ethene and ethane show they are a part of a different series?
They both have different general formulas
C2H4 + Br2 –>?
C2H4Br2
Are smaller Hydrocarbons more or less Viscous?
The smaller the Hydrocarbon the less viscous it is
How to test for chlorine?
Get a piece of damp blue litmus paper and it will turn white
Briefly turns red before turning white (because the chlorine dissolves in the water on the damp paper to form H)
Colours of Acids and ALkalis in Methyl Orange
Yellow: Alkali
Orange: Acid
Why is a burette used instead of a pipette for adding acid?
Different Volumes can be measured
How to go from Cm3 to dm?
Divide by 1000
Why may a reaction not be able to react in the atmosphere?
X reacts with O2, N2, Co2 or Argon
What colours are methyl orange?
Yellow
Orange
What can a student do to ensure accurate Titration Results?
Use Pipette
Concordant Results. REPEAT
Add Acid DROPWISE
Rinse flask with H2O
Arrangement and movement of particles in a gas molecule?
Irregular Far apart Move Freely and Collide with each other No Force between Particles No fixed shape or volume
Why is Catalytic Cracking useful?
Cracking converts long chain hydrocarbons into short chain … Crude oil contains a surplus long chains. … Cracking also produces alkenes which are used in making polymers and ethanol.
How can impurities cause environmental damage?
Fossil fuels such as coal, gas and oil are derived from crude oil.
These fuels are hydrocarbons, but also include impurities such as sulfur.
When the fuels are burned, sulfur dioxide is produced which can escape into the atmosphere:
How does Surface Area increase the Rate of Reaction?
If the surface area of a reactant is increased: more particles are exposed to the other reactant. there is a greater chance of particles colliding, which leads to more successful collisions per second. the rate of reaction increases
