gcse tril chem flashcards - deyes high school...limiting – use moles of mg: m = 40 x 0.21 = 8.3g...
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GCSE Chemistry Trilogy Science
Flashcards
1 - Atomic Structure and the Periodic Table
2 - Structure, Bonding and Properties
3 - Quantitative Chemistry: Calculations
4 - The Rate and Extent of a Chemical Reaction
5 - Chemical Changes: Salts and Electrolysis
6 - Energy Changes
7 - Organic Chemistry
8 - Chemical Analysis
9 - Chemistry of the Atmosphere
10 - Using Resources
Name: ………………………………………………..
1 - Atomic Structure and the Periodic Table
Describe the structure of an atom.
• Atoms contain a nucleus (made of protons and neutrons)
• surrounded by electrons which orbit around in
• shells
Why are atoms neutral? (2 marks)
• The number of protons = the number of electrons
• The charges cancel
Where are elements with similar properties found in the periodic table?
• The same group (vertical column) • E.g. group 1, group 2…
Which groups are the noble gases, the alkali metals and the halogens found in?
• Noble gases = group 0 • Alkali metals = group 1 • Halogens = group 7
In the periodic table, where are the mass
number and atomic number found and what do they tell you about an element?
• Mass number: protons + neutrons
• Atomic number: protons (same as the
number of electrons)
Draw an atom of chlorine (1 mark)
Write the electron configuration of sodium (1
mark)
• 2,8,1
(you need to be able to do this for every element up to Ca)
Describe and explain the trend in reactivity down group 1 ( 4 marks)
• Reactivity increases down group 1 • Atoms get bigger (more shells) • Outer electron gets further away from the
nucleus. • Attraction between nucleus and outer
electron is weaker. • Electron more easily lost.
Describe and explain the trend in reactivity down group 7 (4 marks)
• Reactivity decreases down group 7 • Atoms get bigger • Electron being gained is further from the
nucleus • Therefore attraction is weaker • So electron is harder to gain
Describe and explain the importance of the work of Mendeleev (3 marks)
• He left gaps for undiscovered elements • He ordered atoms in order of their atomic
weight • He organised elements into groups based
on their reactivity
Describe the process of filtration
• Used to separate an insoluble solid from a liquid e.g. to separate sand from water
Describe the process of evaporation
• Used to separate a soluble solid from a liquid e.g. to separate salt from saltwater
Describe the process of distillation
• Used to separate a soluble solid from a liquid and keep both the liquid and the solid.
Describe the process of chromatography and explain why it is used (Required Practical 6)
• Used to separate inks.
Method:
• Place a pencil line of a piece of chromatography paper (stationary phase)
• Use pencil so ink doesn’t run • Place dots of known inks and an unknown
ink on the link. • Place in the solvent (mobile phase) in a
beaker (below the pencil baseline) • Leave to develop • Remove and leave to dry. • Compare known with unknown to identify
what inks are in the unknown sample. • Calculate Rf values
Calculating Rf values:
• VALUE WILL ALWAYS BE LESS THAN 1
List the properties of transition metals
• Form coloured compounds • Conduct electricity • Conduct heat • Malleable (can be hammered into shapes) • Ductile (can be pulled into wires) • Hard • Strong • High melting points
2 - Structure, Bonding and Properties
Describe ionic bonding (4 marks)
1. Between a metal and a non-metal. 2. Transfer of electrons from the metal to the
non-metal. 3. Produces a positive metal ion and a negative
non-metal ion. 4. Oppositely charged ions held together by an
electrostatic interaction.
e.g. NaCl, CaCl2, MgO, Na2O… Make sure you use the example in the question eg: Na transfers one electron to chlorine to form Na+
and Cl-. Ions held together by an electrostatic interaction.
Draw HCl (2 marks)
Draw Cl2
Draw O2
Draw CO2
*You have to be able to draw the covalent bond
between a variety non-metals
Draw CH4
Draw NaCl
Draw MgO
*You have to be able to draw the ionic bond between a variety of metals and non-metals
Draw CaCl2
What is the formula of the ionic compound formed between magnesium and chlorine?
1. Write down the charges on your ions:
Group 1 = +1 Group 2 = +2 Group 3 = +3 Group 6 = -2 Group 7 = -1 Complex ions: Nitrate = NO3
-
Sulphate = SO42-
hydroxide = OH-
2. Magnesium = Mg2+ 3. Chloride = Cl- 4. Drop the charge, swap the number:
Mg2+ Cl-
Mg2 Cl = MgCl2
Describe the structure and bonding in a metal?
(2 marks)
• Lattice of positive metal ions • Surrounded by a sea of delocalised
electrons.
What are the different allotropes of carbon? (allotrope = different forms of the same
element)
• Diamond • Graphite • Graphene (one sheet of graphite) • Graphane • Fullerenes (football shaped) • Carbon nanotubes
Why are atoms neutral? (2 marks)
• Equal number of positive protons and
negative electrons • Cancel.
Why do graphite/grapheme/fullerenes/carbon nanotubes conduct electricity?
(3-4 marks)
• Delocalised electrons • Between the layers • Free to move • Carry charge • Each C has 3 bonds.
Why to atoms react? (1 mark)
• To gain a full outer shell.
Why is graphite slippery? / Why can graphite be used in pencils?
(asking the same thing!) (3 marks)
• Weak interactions/forces • Between the layers • Easy to break.
What is a covalent bond? (2-3 marks)
• Shared pair of electrons • Between 2 non-metals
HT answer:
• Electrostatic attraction between the • Positive nuclei and the • Shared pair of negative electrons
Why does silicon dioxide have a high melting point? / Why can silicon dioxide be used to line
furnaces? (asking the same thing!)
(4-5 marks)
• Each Si has 4 bonds and each O has 2 bonds.
• All bonds are covalent. • Giant covalent structure. • Many strong covalent bongs need to be
broken • So has a high melting point.
How does the covalent bond between HCl form? (3 marks)
• H has 1 outer shell electron • Cl has 7 outer shell electrons • Each share 1 electron to get a full outer shell.
Why can ionic compounds NOT conduct electricity when solid?
(2 marks)
• Ions • In fixed position in the ionic lattice • Cannot carry charge.
Why do simple molecules have low boiling
points? / Why is methane a gas a room temperature?
(asking the same thing!) (3 marks)
• Weak interactions/forces • Between molecules • Easy to break.
Why can ionic compounds conduct electricity when molten?
(2 marks)
• Ions • Free to move and carry charge
Why do simple molecules NOT conduct electricity? (2 marks)
• No delocalised electrons so • Cannot carry a charge.
Why does diamond NOT conduct electricity? (2 marks)
• No delocalised electrons so • Cannot carry a charge.
Why is diamond hard? (4-5 marks)
• Each carbon has 4 covalent bonds • Giant covalent structure • Strong bonds hard to break.
Why can metals conduct electricity? / Why is copper used in wires?
(asking the same thing!) (2-3 marks)
• Delocalised electrons • Free to move and carry charge through the
metal structure.
Why does diamond have haigh melting point? (4 marks)
• Each C has 4 bonds • All bonds are covalent. • Giant covalent structure. • Many strong covalent bongs need to be
broken • So has a high melting point.
Explain the difference in boiling point of HCl and NaCl. (6 marks)
** you can be asked to compare the boiling point of any two compounds so you need to make sure you
can work out what the bonding is!**
• HCl is simple covalent • Exists as molecules • Weak interactions between molecules • Easy to break
• NaCl is ionic • Exists in 3D ionic lattice • Strong electrostatic attraction • Between Na+ and Cl-/oppositely charged
ions • Need a lot of energy to break
• So NaCl has a higher boiling point than HCl
Draw the structure of a metal (2 marks)
Why can metals be hammered into shapes? (2 marks)
• Layers of metal ions • Slide over eachother. • This does not disrupt the structure of the
metallic bond.
How big are nanoparticles?
One billionth of a metre. Or 10-9m Or Very tiny
What is the difference between thermosetting and thermosoftening polymers?
Thermosetting polymers have cross-linked chains. They are formed by putting them into a mould and heating. The resulting structure cannot be reshaped.
Thermosoftening polymers have weak interactions between polymer chains. They can be reshaped when heated.
What are the environmental advantages and disadvantages of using nanoparticles?
• Advantages: long-lasting (e.g. using in tennis
balls), antibacterial properties (e.g. used in smelly socks).
• Disadvantages: Could be toxic if they entered
the bloodstream.
Draw and name the polymer formed by ethene (4 marks)
1 – for n before monomer 2 – for breaking double bond and drawing 2 bonds outside of brackets 3 – for brackets 4 – name = poly(ethene)
Sketch the structure of graphite ( 2 marks)
3 - Quantitative Chemistry: Calculations
What is the relative molecular mass, Mr? The sum of the mass numbers in a molecule or compound
What is the Mr of LiCl? 3 + 35.5 = 38.8
What is the Mr of Ca(OH)2
40 + (2x16) + (2x1) = 74
What equation links mass, molecular mass and moles? Mass = molecular mass x moles m = Mr x n
Rearrange m = Mr x n to calculate n. n = m / Mr
What equation links moles, concentration and volume? Moles = concentration (in mol/dm3) x volume (in dm3) n = c x v
What equation links mass, concentration and volume? Mass (in g) = concentration (in g/dm3) x volume (in dm3) m = c x v
What is the maximum mass of magnesium oxide that can be formed from 5 g of Magnesium and 12 g of oxygen? (4 marks) – Limiting reagent question! (They have given you information about both reactants)
2Mg + O2 à 2MgO
1. Work out the moles of Mg 2. Work out the moles of O2 3. Work out which moles are in excess and which
are limiting – the limiting you use in your reacting masses calculation.
4. Write down the Mr of the limiting reagent and MgO
5. Work out the molar ratio 6. Work out the moles of MgO that would be
produced 7. Work out the mass of MgO
2Mg + O2 à 2MgO
m = 5g m = 12g Mr = 24 Mr = 16 n = 5/24 = 0.21
n = 12/16 = 0.75
0.21 moles of Mg needs 0.21/2 = 0.105 moles of O2 We have 0.75 g of O2, so O2 is in excess and Mg is limiting – USE MOLES OF Mg:
m = 40 x 0.21 = 8.3g Mr MgO = 24 + 16 = 40 n = 0.21 (as 1:1)
*you have to be able to do this for any equation with any ratio and any quantities given
What is the maximum mass of magnesium oxide that can be formed from 5 g of Magnesium? (3 marks)
2Mg + O2 à 2MgO 1. Work out the moles of Mg 2. Write down the Mr of Mg and MgO 3. Work out the molar ratio 4. Work out the moles of MgO that would be
produced 5. Work out the mass of MgO
2Mg + O2 à 2MgO
m = 5g m = 40 x 0.21 = 8.3g
Mr = 24 Mr = 24 + 16 = 40
n = 5 / 24 = 0.21 n = 0.21 (as 1:1)
*you have to be able to do this for any equation with any ratio and any quantities given
What is a titration? A neutralisation reaction used to find the unknown concentration of the acid or alkali using a known concentration of the other. (required practical 2)
Name the apparatus used in a titration.
Calculate the concentration of sodium hydroxide if 25 cm3 needed 23.25 cm3 of 0.1 mol/dm3 hydrochloric acid for neutralisation ( 3 marks) (HT only)
HCl + NaOH à NaCl + H2O
1. Write down the volumes in dm3 (cm3 /1000) of HCl and NaOH
2. Write down the concentration of HCl 3. Calculate the moles of HCl 4. Calculate the molar ratio 5. Calculate the concentration of NaOH
HCl + NaOH à NaCl + H2O
n = 0.1 x 0.02325 = 0.002325
n = 0.002325
c = 0.1 mol/dm3 c = 0.002325/0.025 = 0.093 mol/dm3
v = 0.02325 dm3 v = 0.025 dm3
*you have to be able to do this for any equation with any ratio and any quantities given
5 - Chemical Changes: Salts and Electrolysis
What is oxidation in terms of oxygen? (1 mark) Gain of oxygen
What is reduction in terms of oxygen? (1 mark) Loss of oxygen
What are oxidation and reduction in terms of electrons? (2 marks) Oxidation is loss of electrons Reduction is gain of electrons
Think OILRIG!
Are the following oxidation or a reduction?
1. Na+ + e- à Na Reduction
2. 2Cl- à Cl2 + 2e- (Can also be written 2Cl- - 2e-à Cl2)
Oxidation
Examples of acids: • Hydrochloric acid (HCl) • Sulphuric acid (H2SO4) • Nitric acid (HNO3)
Examples of alkalis:
• Metal hydroxide (e.g. sodium hydroxide, NaOH))
• Metal oxide (e.g. sodium oxide, Na2O)
Naming salts The salt produced is named from the acid used:
Acid used Metal salt produced Hydrochloric acid Chloride
Sulphuric acid Sulphate Nitric acid nitrate
What is the ionic equation for neutralisation? (1 mark)
• H+ + OH- à H2O
Acid + alkali à salt + water e.g. hydrochloric acid + sodium hydroxide à sodium chloride + water
• Neutralisation reaction
Acid + carbonate à salt + water +
carbon dioxide
e.g. nitric acid + lithium carbonate à lithium nitrate + water + carbon dioxide
Acid + metal à salt + hydrogen
e.g. sulfuric acid + potassium à potassium sulfate + hydrogen
What is a strong acid? (2 marks)
• Fully dissociates • In solution
e.g. HCl à H+ + Cl-
What is a weak acid? (2 marks)
• Partially dissociates • In solution
e.g. CH3OOH H+ + CH3COO-
What is the pH of a strong acid and a weak acid? Strong acid = pH 0-2 (red in universal indicator) Weak acid = pH 3-5 (orange/yellow in universal indicator)
How can you test to see whether a solution is neutral? Universal indicator turns green Or pH meter gives a reading of 7.0 (most accurate)
What is electrolysis? (1 mark)
• Splitting up ionic compounds using electricity
Describe and explain how crystals of copper sulfate can be produced (6 marks)
(Required practical 1)
1. Add an excess of copper oxide to sulphuric acid to react via the following equation:
Copper oxide + sulphuric acidàcopper sulfate + water CuO(s) + H2SO4(aq) à CuSO4 (aq) + H2O(l)
2. An excess of copper oxide is added to ensure all of the sulphuric acid reacts.
3. Filter off any unreacted CuO(s) ß insoluble. 4. Pour the copper sulfate solution (blue) into
an evaporating dish. 5. Heat using a Bunsen burner to remove half
the water and start crystallisation. 6. Leave to evaporate, leaving crystals of pure
copper sulfate (CuSO4)
Why does the electrolyte need to be molten or in solution for electrolysis to work? (2 marks)
• So the ions • Can move
Label a diagram showing the set-up of equipment used in electrolysis
(Required practical 4)
Describe and explain how crystals of copper lead iodide using the following equation
(4 marks) Pb(NO3)2(aq) + 2KI(aq) à PbI2(s) + 2KNO3(aq)
1. Add lead nitrate to potassium iodide solution in a 1:2 ratio.
2. Solid lead iodide (yellow) is produced. 3. Filter off the solid, insoluble lead iodide
from the unreacted lead nitrate and potassium iodide and potassium nitrate solution products.
4. Wash with distilled water. 5. Leave to dry.
Describe the electrolysis of brine/sodium chloride solution/ NaOH(aq) and explain why
three products are made (6 marks)
• Ions in solution = Na+, Cl-, H+ and OH- • Na+ and Cl- from sodium chloride • H+ and OH- from the water (solution) • H+ moves to negative electrode to produce
hydrogen gas (H2) o Half equation: 2H+ + 2e- à H2
• Cl- moves to positive electrode to produce chlorine gas (Cl2)
o Half equation: 2Cl- à Cl2 + 2e- • Na+ and OH- left in solution form sodium
hydroxide (NaOH). •
**THE MOST REACTIVE POSITIVE ION STAYS IN SOLUTION
Describe the process of electrolysis of aluminium oxide (Al2O3), stating the products and explaining how they are formed (6 marks)
• Heated until molten (melted) • Cryolite added to lower melting point • Ions = Al3+ and O2- • Al3+ moves to negative electrode to produce
aluminium (Al) o Half equation = Al3+ + 3e- à Al
• O2- moves to positive electrode to produce oxygen (O2)
o Half equation = 2O2- à O2 + 4e- • O2 reacts with carbon electrodes to form
carbon dioxide (CO2) o C(s) + O2(g) à CO2(g)
• Carbon electrodes therefore need to be replaced frequently as they ware away.
State the chemical tests for the products of electrolysis of NaOH(aq) and describe their uses
(6 marks) Test for products:
• Cl2 – bleaches litmus paper • H2 – lit splint pops • NaOH (pH 14) – turns universal indicator
paper blue Uses of products:
• Cl2 – bleach • H2 – making margarine • NaOH - making soap
2 types of electrolysis: 1. Molten Look at the
e.g. PbBr2 (l) state symbol!
Ions present: Pb2+ Br- 2. Aqueous
e.g. CaCl2(aq)
Ions present: Ca2+ Cl- H+ OH-
**In aqueous electrolysis, THE MOST REACTIVE + ION STAYS IN SOLUTION and the LEAST REACTIVE FORMS THE PRODUCT at the cathode. At the anode, if NO3
-, OH- or SO42- are present,
oxygen is produced. Writing half-equations:
1. Look at the charge on the ion 2. Swap it around to write the number of
electrons e.g. Ca2+ +2e- à Ca e.g. 2O2- -4e- à O2
The Reactivity Series (learn!)
A more reactive element can displace a less reactive element within a compound. e.g. CuSO4 + Mg à MgSO4 + Cu
List the metals that can be extracted using carbon (reduction). Zinc Iron Tin Lead Copper
Which metals do not need to be extracted and why?
Gold Platinum Are unreactive and so exist native. They exist as pure elements and do not need to be extracted from compounds.
Which elements need to be extracted by electrolysis and why?
Potassium Sodium Calcium Magnesium Aluminium They are too reactive and therefore cannot be displaced by carbon from their compounds
6 - Energy Changes
Define exothermic (2 marks)
• Gives out heat energy • To the surroundings
ΔH is negative
Describe how you could determine the point of
neutralisation in an acid-base reaction by measuring the temperature.
(Required practical 4)
• Add 25 cm3 of acid to a polystyrene cup (for insulation)
• Record the start temperature • Add 5 cm3 of alkali and record the temperature • Add 5 cm3 of alkali until you have added 40 cm3
in total, recording the temperature each time. • Plot a graph of volume of alkali added (x axis)
against temperature (y axis) • Draw two lines of best fit. • Find the intersect of the two lines and read the
value off the x-axis: This is the volume of alkali needed to neutralise the 25cm3 of acid.
Volumeofalkaliadded**Use the values in the question (the values here are just an example) Acid/alkali may be the other way around – read the question!
Define endothermic (2 marks)
• Take in heat energy • From the surroundings
ΔH is positive
Describe a simple experiment you could do to find out whether a reaction is exothermic or
endothermic.
• Measure the change in temperature. • If the temperature increases (gets hotter) =
exothermic • If the temperature decreases (gets colder) =
endothermic
Enthalpy change (ΔH) using bond enthalpies: ΔH = Sum of bonds broken – sum of bonds made
Calculate the enthalpy change of the following reaction using the following bond enthalpies:
CH4 + 2O2 à CO2 + 2H2O
ΔH = [(4x412) + (2x498)] - [(2x743) + (4x463) = [1648 + 996] - [1486 + 1852) = 2644 – 3338 = -694 kJ/mol ** you have to be able to do this for any equation
Bond Mean bond enthalpy (kJ/mol) C-H 412 O=O 498 C=O 743 O-H 463
What equation can be used to calculate the heat energy released by a reaction?
q = m x c x ΔΤ
heat energy (J) = mass of water x specific heat capacity of water (4.2) x change in temperature
What equation allows us to calculate the enthalpy change of a reaction in kJ/g?
ΔH = q / mass of fuel burned (g) What equation allows us to calculate the enthalpy change of a reaction in kJ/mol?
ΔH = q / moles of fuel burned (moles)
**Remember moles = mass / Mr!!
1.5 g of ethanol (C2H5OH) was burned. This caused the temperature of 50 cm3 of water to rise by 14 oC. Calculate the enthalpy change for the reaction in kJ/mol. q = mcΔT = 50 x 4.2 x 14 = 2940 J n = m/Mr = 1.5/((12x2)+16+6) = 1.5 / 46 = 0.0326 moles of ethanol ΔH = q/n = 2.940 KJ / 0.0326 ß don’t forget to convert q to kJ = - 90.18 kJ/mol ß add – sign as reaction gets hotter so is exothermic
1.2 g of ethanol (C2H5OH) was burned. This caused the temperature of 100 cm3 of water to rise by 8 oC. Calculate the enthalpy change for the reaction in kJ/g. q = mcΔT = 100 x 4.2 x 8 = 3360 J ΔH = q/m = 3.360 KJ / 1.2 ß don’t forget to convert q to kJ = - 2.8 kJ/mol ß add – sign as reaction gets hotter so is exothermic
7 - The Rate and Extent of a Chemical Reaction
What is meant by the term ‘rate of reaction’ (2 marks)
• The speed at which reactants • are converted into products
How does increasing the concentration affect the rate of reaction? Explain your answer.
(4-5 marks) *you also have to be able to explain decreasing the
concentration*
• increases the rate of reaction • more particles • in same volume • more collisions • that are successful
How does increasing the temperature affect the
rate of reaction? Explain your answer. (4 marks)
*you also have to be able to explain decreasing the temperature*
• increases the rate of reaction • particles have more energy • move more • more collisions • that are successful
How does increasing the pressure affect the rate of reaction? Explain your answer.
(4-5 marks) *you also have to be able to explain decreasing the
pressure*
• increases the rate of reaction • same number of particles • in a smaller volume • more collisions • that are successful
How does decreasing the surface area affect
the rate of reaction? Explain your answer. (4 marks)
*you also have to be able to explain increasing the surface area*
• decreases the rate of reaction • less surface available for particles to react on • so less collisions • than are successful.
How does adding a catalyst affect the rate of reaction? Explain your answer.
(4 marks)
• speeds up the reaction • provides another route for the reaction • that requires less energy • is not changed itself so can be reused.
What is collision theory? (2 marks)
• particles must collide • with enough energy for a reaction to happen.
What five factors can affect the rate of a chemical reaction?
• Temperature • Pressure • Catalyst • Concentration • Surface area
How does the rate of reaction change with time at 40 oC
(3 marks)
• Fast initially • Slows • Then stops
Explain your answer (3 marks)
• because the reactants are used up • So the concentration decreases • So there is less chance of successful collision
Time
Amou
ntofp
rodu
ct
evolved
20°C
30°C
40°C
Define Le Chalelier’s Principle A system at equilibrium will move to oppose the change created by any external conditions that are applied
Define dynamic equilibrium
A reversible reaction in a closed system (nothing can get in or out). The concentration of reactants and products remains constant unless an external change in conditions is applied
What is the symbol used in a reversible reaction (an equilibrium)?
Describe and explain how the yield of C would change if the pressure of the following reaction
was increased (3 marks)
A + 2B C + D
• The yield of C would increase • There are 3 moles on the left and 2 on the right • The equilibrium would shift to the right (to the
side with less moles) to try and reduce the pressure.
Describe and explain how the yield of C would change if the temperature of the following
reaction was increased (3 marks)
A + 2B 2C + D ΔH = -190 kJ/mol
• The yield of C would decrease • The forwards reaction is exothermic • The reaction would move to the left in the
endothermic direction to try and reduce the increase in temperature.
Describe and explain how the yield of C would change if the pressure of the following reaction
was increased (3 marks)
A + 2B 2C + D ΔH = -160 kJ/mol
• The yield of C would stay the same • There are the same number of moles on each
side. • The equilibrium position would not change
Describe and explain how the yield of D would change if the concentration of C in the
following reaction was increased (2 marks)
A + 2B C + D ΔH = -120 kJ/mol
• The yield of D would decrease • The equilibrium would move to the left to try and
reduce the increased amount of C
Describe and explain how the yield of C would change if a catalyst was added to the following
equilibrium (3 marks)
A + 2B 6C + D ΔH = +90 kJ/mol
• The yield of C would not change • The equilibrium would be established quicker as
the catalyst would speed up the rate of reaction in both directions equally.
• The position of equilibrium would not change.
7 - Organic Chemistry
What is crude oil and how is it formed?
Crude oil is a mixture of hydrocarbons (1 mark) It formed millions of years ago when plankton became trapped under layers of sediment and did not decompose. This has turned into crude oil over time. (1 mark)
What is a hydrocarbon ( 1 mark)
A compound that contains carbon and hydrogen only
What is an alkane? (1 mark)
A hydrocarbon that contains single bonds only
What is an alkene? (1 mark)
A hydrocarbon that contains double bonds
Name and draw the first four alkanes
Name and draw the first four alkenes
Explain why ‘methene’ does not exist (2 marks)
• Methene would only have one carbon • Therefore it could not contain a C=C double
bond
What is the general formula of an alkane (1 mark)
CnH2n+2
What is the general formula of an alkene (1
mark)
CnH2n
What is the general formula of an alcohol (1 mark)
CnH2n+1OH
Define saturated and unsaturated
• Saturated = contains single bonds only • Unsaturated = contains double bonds
Describe the chemical test for unsaturation (double bonds/alkenes) (2 marks)
• Bromine water • Orange to colourless
What is the general formula of a carboxylic
acid (1 mark)
CnH2n+1COOH
Define homologous series
A group of compounds with the same general formula
Draw and name the first four alcohols
Draw ethyl ethanoate and state what homologous series this molecule belongs to
This is an ester
Draw and name the polymer formed by ethene (4 marks)
1 – for n before monomer 2 – for breaking double bond and drawing 2 bonds outside of brackets 3 – for brackets 4 – name = poly(ethene)
Explain how fractional distillation separates crude oil into useful fractions (4 marks)
• Crude oil is evaporated by heating • The molecules move up the fractionating
column with the temperature gradient – hot at the bottom and cooler at the top)
• Different fractions condense at their boiling point.
• Different fractions have different boiling points:
• Large molecules have higher boiling points and are found at the bottom
• Small molecules have higher boiling points and condense at the top.
What is cracking (1 mark)
Large hydrocarbons are broken down into smaller, more useful fractions
Describe the process of cracking (2 marks)
• Heat to vaporise • Pass over a catalyst
State the differences between fractional distillation and cracking
• Fractional distillation is a physical process,
cracking is a chemical change • Fractional distillation separates a mixture,
cracking breaks large molecules into small ones
Write an equation to show how decane, C10H22, is broken down into butane, propane and
propene
C10H22 à C4H10 + C3H8 + C3H6
Define complete combustion
• Complete combustion is when a fuel is completely burned in oxygen.
• The products are carbon dioxide and water
e.g. CH4 + 2O2 à CO2 + 2H2O
Define incomplete combustion
• Complete combustion is when a fuel is completely burned in oxygen.
• The products are carbon monoxide or carbon and water
e.g. CH4 + 1.5O2 à CO + 2H2O CH4 + O2 à C + 2H2O
8 - Chemical Analysis
Define a ‘pure’ substance (1 mark)
Contains only one type of atom/molecule
What is a formulation? (1 mark)
A mixture of chemicals with a consistent composition so all products are the same
What is the chemical test for oxygen? (2 marks)
• Glowing splint • Relights
What is the chemical test for hydrogen? (2 marks)
• A lit splint • pops
What is the chemical test for carbon dioxide?
(2 marks)
• Limewater • Turns cloudy
What is the chemical test for chlorine? (2 marks)
• Litmus paper • Bleaches white
What are the advantages and disadvantages of
instrumental methods
Advantages: • Quick • Sensitive (can use a very small sample) • Accurate
Disadvantages:
• Expensive • Special training needed to use equipment • Results need to be compared with spectra of
known substances
9 - Chemistry of the Atmosphere
State the composition of the atmosphere today (3 marks)
• Nitrogen – 78 % • Oxygen – 21 % • Carbon dioxide – 0.03 %
Describe the main differences between the early atmosphere and the atmosphere today
• Lots more nitrogen (none in early
atmosphere vs 78 % now) • Lots more oxygen (none in early
atmosphere vs 21 % now) • Less carbon dioxide (0.03 % now vs 96 %
then)
Describe and explain the change in the concentration of carbon dioxide in the Earth’s
atmosphere over time (3 marks)
• It has decreased because:
• Photosynthesis of plants • Dissolved in the oceans • Formed carbonate rocks (eg calcium
carbonate/limestone) • Locked up in fossil fuels
Describe and explain the change in the concentration of oxygen in the Earth’s
atmosphere over time (2 marks)
• It has increased because:
• Photosynthesis of plants
Explain how carbon dioxide cause global warming/ Describe how carbon dioxide helps
to maintain temperatures on Earth. (3 marks) (grade 9)
• Carbon dioxide allows short wavelength
radiation to pass through the atmosphere to the Earth’s surface
• Carbon dioxide absorbs outgoing long wavelength radiation
• This traps the heat in the atmosphere.
State the main greenhouse gases
• Carbon dioxide – CO2 • Methane – CH4
Write an equation for the incomplete combustion of ethane to form a gaseous product (2 marks – 1 for formulae, 1 for
balancing)
C2H6(g) + 2.5O2(g) à 2CO(g) + 3H2O (l)
Write an equation for the incomplete combustion of propane to form a solid product
(2 marks – 1 for formulae, 1 for balancing)
C3H8(g) + 2O2(g) à 3C(s) + 4H2O (l)
State the environmental effects of the products of combustion
Gas Effect
Carbon dioxide - CO2 Global warming Methane – CH4 Global warming
Carbon monoxide – CO Toxic Particulates - C Global dimming
Sulfur dioxide – SO2 Acid rain Nitrogen oxides - NOx Acid rain
Write an equation for the combustion of propanol (2 marks – 1 for formulae, 1 for
balancing)
C3H7OH(g) + 5O2(g) à 3CO2(s) + 4H2O (l)
What are the four main contributions to global warming made by humans?
• Deforestation • Burning fossil fuels • Animal farming • Decomposition of landfills
What is a carbon footprint?
A carbon footprint is an estimate of the impact that activities have on climate change – such as making a product, living a lifestyle or running a company.
10 - Using Resources
Define finite (1 mark)
• Resources that are being used up faster than they can be replaced.
• These resources will eventually run out (e.g fossil fuels)
Define renewable (1 mark)
• Can be replaced at the same rate at which they are being used up.
• E.g. Crops grown to make biofuels and wood are examples of these types resources.
Define potable (1 mark)
• Water that is safe to drink
Describe and explain the stages involved in making saltwater/seawater potable – 2
methods (3 marks each)
• Desalination using distillation: • Heat the saltwater to evaporate the water,
leaving the salt behind. • Condense the water by cooling. • Collect freshwater and add chlorine to kill
bacteria
• Reverse osmosis • Apply pressure to saltwater • Force it through a semi-permeable
membrane, which will not let salt through • Collect freshwater and add chlorine to kill
bacteria
Define pure (1 mark)
1. A substance that contains one type of particle
2. e.g. Neon contains only Na atoms 3. e.g. Carbon dioxide contains only CO2
molecules
Describe and explain the stages involved in making freshwater potable (3 marks)
1. Filter to remove large particles 2. Add aluminium sulphate to cause smaller
particles to clump together 3. Filter through a sand bed 4. Add chlorine to kill bacteria and
microorgnisms
Evaluate the two methods of treating saltwater
Advantages of distillation: • Pure water at the end • Quick
Disadvantages of distillation:
• High energy cost Advantages of reverse osmosis:
• No heating, so lower energy cost than distillation
Disadvantages of reverse osmosis:
• Still some energy cost in applying pressure • Salt can erode the membrane over time so it
will need to be replaces • Process only removes 98 % of salt.
Describe and explain the stages involved in treating waste water (4 marks)
1. Filter to remove large impurities 2. Sedimentation to remove sludge 3. Biological treatment with bacteria to kill
microbes 4. Sedimentation to remove secondary sludge 5. (3 and 4 can be repeated) 6. Add chlorine to kill bacteria 7. Put water back into rivers
What is an ore? (1 mark)
A rock that contains enough metal to be extracted economically
What happens to the sludge produced in the treatment of waste water?
Pros:
• Dried to form a ‘cake’ which can be used as a fuel
• Can be used as a fertiliser Cons:
• Can go to landfill
Why can we not always treat freshwater (even though it is the simplest form of water
treatment?
• Some hot countries have a very limited supply of freshwater as it evaporates from lakes and reservoirs
• Seawater must be used instead.
What is phytomining and explain how it is used to extract copper?
Extraction of copper from contaminated ground containing low grade copper ore using plants.
• Plants are grown on land containing low grade copper ore.
• The plants absorb Cu2+ ions through their roots.
• The plants are burned, producing ash containing copper oxide (CuO)
• The ash is dissolved in sulphuric acid (H2SO4)
• The copper is extracted from the solution using electrolysis.
* remember it needs to be in solution so the ions can move!
What is the difference between low grade and high grade ore?
• High grade ore contains enough metal
oxide to extract the metal economically using reduction using carbon/smelting.
• Low grade ore only contains very small amounts of metal oxide – not enough to extract it profitably.
Explain how scrap iron can be used to extract
copper
• Iron is more reactive than copper • It will displace copper in a compound
leaving an iron compound and copper
e.g. 2Fe + 3CuO à 3Cu + Fe2O3
What is bioleaching explain how it is used to extract copper?
Extraction of copper from low grade ores using bacteria
• Bacteria is added to low grade ore and
absorb copper compounds • The bacteria produces a solution called a
leachate that contains copper ions.
Evaluate bioleaching and phytomining as methods of extracting copper (6 marks)
• Advantages are that both phytomining and
bioleaching can be used to extract Cu from low grade ores.
• Disadvantage is that both are slow. • Advantage is phytomining can be made
quicker by using fast growing plants • Advantage is phytomining can be used on
contaminated ground. • Advantage of bioleaching is it can be used
on waste from quarries. • Disadvantage of bioleaching is it produced
toxic chemicals that can flow into rivers.
What is an LCA?
• A Life Cycle Assessment • An assessment of the impact a product has
on the environment throughout its whole life
What are the 5 stages in a LCA?
• Raw materials • Production • Transportation • Product use • Disposal
What is a value judgement?
• A subjective opinion on the impact of a
process on the environment.
• e.g. We can quantify (objectively) the amount of CO2 released into the atmosphere. We cannot quantify (put a number on) the impact this has on the level of global warming/the effect it has on the atmosphere (subjective)
Evaluate the limits of LCAs (6 marks)
We can quantify: • How much water is used • How many resources are used • How much energy used • How much waste is produced This is objective and scientific We cannot quantify:
• The effect of pollutants on the atmosphere • The effect of extracting resources on the
environment We have to use value judgements These are subjective and based on opinion
• LCAs can be abbreviated to quote facts a company wants to advertise but leave out other facts. E.g. The product can be reused which is good for the environment, but leave out the fact the transportation of the product to shops causes global warming through burning fuels.
• LCAs need to be peer-reviewed in order to be trusted.
What is the importance of peer-reviewing in science?
• Allows scientific claims to be checked and
verified by someone not linked to the company.
• Removes bias.
Required Practicals
Practical Activity 1
Preparation of a pure, dry sample of a soluble salt from an insoluble oxide or carbonate, using a Bunsen burner to heat dilute acid and a water bath or electric heater to evaporate the solution.
Practical Activity 2 (Triple only)
Determination of the reacting volumes of solutions of a strong acid and a strong alkali by titration.
Determination of the concentration of one of the solutions in mol/dm3 and g/dm3 from the reactive volumes and known concentration of the other solution
Practical Activity 3
Investigate what happens when aqueous solutions are electrolysed using inert electrodes. This should be an investigation involving developing a hypothesis
Practical Activity 4
Investigate the variables that affect temperature changes in reacting solutions such as, eg acid plus metals, acid plus carbonates, neutralisations, displacement of metals
Practical Activity 5
Investigate how changes in concentration affect the rates of reactions by a method involving measuring the volume of a gas produced and a method involving a change in colour or turbidity. This should be an investigation involving developing a hypothesis.
Practical Activity 6
Investigate how paper chromatography can be used to separate and tell the difference between coloured substances. Substances should be able to calculate Rf values.
Practical Activity 7 (Triple only)
Use of chemical tests to identify the ions in unknown single ionic compounds covering the ions from sections Flame tests through to Sulfates
Practical Activity 8
Analysis and purification of water samples from different sources, including pH, dissolved solids and distillation
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