A-Level Chemistry

Introduction

Chemistry

• Assumes a good knowledge of GCSE chemistry – you need to be confident with all that work!
• Splits into three sections:
• Organic
• Inorganic
• Physical
• The full specification and information about assessment can be found on the exam board website:
• www.aqa.org.uk/subjects/science/as-and-a-level/chemistry-7404-7405/specification-at-a-glance

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Chemistry Assessment

• 3 two-hour exams at the end of the course
• Mixture of longer answer, short answer and multiple choice questions (no essays)
• 15% of exam marks are about practical work
• 20% of exam marks on mathematical skills (GCSE Higher Content)

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Chemistry Practical Work

• Many of your lessons will involve a practical or demonstration element as part of teaching the theory
• Practical skills are assessed during at least 12 compulsory experiments – separate pass/fail grade (practical endorsement)
• Practical work is written up in laboratory book – moderated by exam board

• scientific calculator required for all lessons
• if you are not taking A Level maths, do not panic!

20% of marks are for Level 2 (GCSE) maths skills

Look out for this guide if you think you will need some extra support with the maths aspects of the course.

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Useful revision guides and textbooks available for the course (AQA A Level Chemistry)

Summer Work

Part 1 – learn about mass spectrometry

Part 2 – your own consolidation

• Use your GCSE revision guide or textbook to review the GCSE course in advance of September. All basics must be understood.
• You may wish to consider the CGP guide below which is very useful but not required (can buy online)

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�Calculations. Use your notes to have a go at these mole calculations

1. The relative atomic mass (Ar) of H = 1, C = 12, O = 16, Na = 23, S = 32, Cl = 35.5, Ca = 40, Fe = 56.

What is the relative formula mass or molecular mass (Mr) of a) H₂O b) NaCl c) CaCO₃ d) C₂H₅OH e) FeSO₄ ?

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2. Ar C = 12. How many moles of carbon are there in a) 12g b) 24g c) 6g d) 1.2g e) 0.06g ?

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3. Consider the reaction CaCO₃ 🡪 CaO + CO₂ then answer the following questions (use Ar values in Q1).

a) What is the maximum number of moles of CaO that can be produced from 1 mole of CaCO₃?

b) Starting from 10g of CaCO₃ i) how many moles of CaCO₃ is this?

ii) what is the maximum number of moles of CaO that this could produce?

iii) what is the maximum mass of CaO that can be produced?

iv) if a student actually produced 3.6g of CaO in this reaction,

what is the % yield?

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4. Research activity.

In the reaction C₂H₄ + H₂O 🡪 C₂H₆O the atom economy is said to be 100%.

Explain what this means and why it is an important consideration in industrial processes.

Is the atom economy for the reaction in Q3 also 100%? How do you know?

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1. a) 18 b) 58.5 c) 100 d) 46 e) 152

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• a) 1 b) 2 c) 0.5 d) 0.1 e) 0.005 (5 x 10^-3)

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• a) 1 mole

b) i) 0.1

ii) 0.1

iii) 5.6

iv) 64.3%

Chemistry Induction – Calculation answers

Induction Lesson

1. Using the ions given, write down the formulae for the following

ionic compounds (make sure the charges are balanced).

1. sodium chloride b) potassium hydroxide c) magnesium bromide

d) copper sulphate e) iron(II) nitrate f) iron(III) sulphate g) calcium carbonate h) lithium nitrate

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2. Complete and then balance the following ionic equations;

1. Ag⁺ + CO₃^2- 🡪 ________ b) Cu²⁺ + OH^- 🡪 ________ c) Fe²⁺ + CO₃^2- 🡪 _______
4. Pb²⁺ + I^- 🡪 ________ e) Al³⁺ + OH^- 🡪 ________ f) Ba²⁺ + SO₄^2- 🡪 _______

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3. Copy, complete and balance the equations for the following precipitation reactions, including state symbols;

1. NaCl + AgNO₃ 🡪 _____ + _____ b) Na₂SO₄ + BaCl₂ 🡪 ______ + ______ c) Pb(NO₃)₂ + KI 🡪 _____+_____

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4. Write ionic equations (including state symbols) for the precipitation reactions in Q3. You will need to look up which product is the insoluble precipitate (soluble spectator ions are not written in ionic equations).

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5. Balance the following equations;

1. Mg + HCl 🡪 MgCl₂ + H₂ b) N₂ + H₂ 🡪 NH₃ c) C₂H₆ + O₂ 🡪 CO₂ + H₂O
4. Pb(NO₃)₂ 🡪 PbO + NO₂ + O₂ e) Al + O₂ 🡪 Al₂O₃ f) C₃H₅N₃O₉ 🡪 CO₂ + H₂O + N₂ + O₂

Extension: research the state symbols for these reactions.

Induction Lesson - answers

1. a)NaCl b) KOH c) MgBr₂ d) CuSO₄ e) Fe(NO₃)₂ f) Fe₂(SO₄)₃ g) CaCO₃ h) LiNO₃

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2. a) 2Ag⁺ + CO₃^2- 🡪 Ag₂CO₃ b) Cu²⁺ + 2OH^- 🡪 Cu(OH)₂ c) Fe²⁺ + CO₃^2- 🡪 FeCO₃

d) Pb²⁺ + 2I^- 🡪 PbI₂ e) Al³⁺ + 3OH^- 🡪 Al(OH)₃ f) Ba²⁺ + SO₄^2- 🡪 BaSO₄

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3. a) NaCl(aq) + AgNO₃(aq) 🡪 AgCl(s) + NaNO₃(aq) b) Na₂SO₄(aq) + BaCl₂(aq) 🡪 BaSO₄(s) + 2NaCl(aq)

c) Pb(NO₃)₂(aq) + 2KI(aq) 🡪 PbI₂(s) + 2KNO₃(aq)

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4. a) Ag⁺ (aq) + Cl^- (aq) 🡪 AgCl(s) b) Ba²⁺ (aq) + SO₄^2- (aq) 🡪 BaSO₄(s) c) Pb²⁺ (aq) + 2I^- (aq) 🡪 PbI₂ (aq)

5. a) Mg + 2HCl 🡪 MgCl₂ + H₂ b) N₂ + 3H₂ 🡪 2NH₃

c) C₂H₆ + 3.5 O₂ 🡪 2CO₂ + 3H₂O (or x2 to remove ½ i.e. 2C₂H₆ + 7O₂ 🡪 4CO₂ + 6H₂O – both correct)

d) 2Pb(NO₃)₂ 🡪 2PbO + 4NO₂ + O₂

e) 4Al + 3O₂ 🡪 2Al₂O₃

f) 4C₃H₅N₃O₉ 🡪 12CO₂ + 10H₂O + 6N₂ + O₂

(nitroglycerine)

Addional activities

1. Explain what is meant by a) the empirical formula and b) the molecular formula of a compound

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• Give the empirical formula of a compound with molecular formula a) C₆H₆ b) C₄H₆Cl₂ c) C₃H₆

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• The family of organic compounds called the Alkanes are all hydrocarbons. They have a general formula of C_nH_(2n+2)

a) What is meant by a hydrocarbon?

b) Using the general formula (where n = 1, 2, 3…etc.), write down the molecular formula for the first 4 alkane compounds and name them

c) Give the molecular formula for the alkane which contains 14 C atoms

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4. There are 5 possible alkanes all with the same molecular formula C₆H₁₄ . Draw out these structures and show the arrangement of all the atoms and bonds (displayed formula)

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• Research activity

Limonene is a hydrocarbon that can be extracted from the peel of citrus fruits. There are two possible arrangements for the atoms in the limonene molecule (isomers) . One of these molecules smells of oranges and the other smells of lemons.

Find out what the difference between the molecules is and why they have different smells.

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Additional activities - answers

1. a) the empirical formula is the simplest ratio of atoms of each element present in a compound

b) the molecular formula gives the actual number of atoms of each element in one molecule of the compound

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2. a) C₆H₆ (CH) b) C₄H₆Cl₂ (C₂H₃Cl) c) C₃H₆ (C₃H₆)

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3. a) compounds that contain hydrogen and carbon ONLY

b) CH₄ methane, C₂H₆ ethane, C₃H₈ propane, C₄H₁₀ butane

c) C₁₄ H₃₀

4. (shown as skeletal formulae not displayed formulae – you should put in all the atoms and bonds)

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