Predicting and Identifying Reactions | OCR GCSE Chemistry A, Foundation tier (J248)
Predicting and Identifying Reactions
- 113 questions
- 9 subtopics
- Paper 2
- Paper 2
Predicting and Identifying Reactions is examined in Chemistry A Paper 2.
It covers groups 1, 7 and 0, and why they behave as they do, transition metals, predicting reactivity from the Periodic Table, reactivity of metals with water and acids, tests for oxygen, hydrogen, carbon dioxide and chlorine, tests for aqueous cations and anions, flame tests, and identifying metal ions, identifying a species from test results and instrumental methods of analysis.
Sample questions from Predicting and Identifying Reactions
Answer each one closed book first, then open the answer.
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Groups 1, 7 and 0, and why they behave as they do
In what form do the elements of Group 7 exist?
Show the answer
As diatomic molecules of two atoms sharing a pair of electrons, such as Cl₂ and Br₂. -
Transition metals
What colours are solutions containing copper(II) ions, iron(II) ions and iron(III) ions?
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Copper(II) solutions are blue, iron(II) solutions are pale green and iron(III) solutions are orange-brown. -
Predicting reactivity from the Periodic Table
Predict the formula of the compound formed between potassium and iodine.
Show the answer
KI, because potassium loses one electron and iodine gains one. -
Reactivity of metals with water and acids
Compare how magnesium reacts with cold water and with steam.
Show the answer
It reacts extremely slowly with cold water, but burns vigorously in steam to form magnesium oxide and hydrogen. -
Tests for oxygen, hydrogen, carbon dioxide and chlorine
Describe the test for chlorine and its positive result.
Show the answer
Hold damp blue litmus paper in the gas; chlorine turns it red and then bleaches it white. -
Tests for aqueous cations and anions
What is seen when sodium hydroxide solution is added to a solution containing zinc ions?
Show the answer
A white precipitate forms first, and it dissolves in excess sodium hydroxide to give a colourless solution. -
Flame tests, and identifying metal ions
Why is a blue flame used for a flame test rather than a yellow one?
Show the answer
A yellow flame is already coloured, so it would hide the colour produced by the metal ions. -
Identifying a species from test results
A green solid gives a green precipitate with sodium hydroxide and fizzes with dilute acid, giving a gas that turns limewater milky. Name the solid.
Show the answer
Iron(II) carbonate.
The 9 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Groups 1, 7 and 0, and why they behave as they do | The physical properties of the Group 1 metals and their reaction with water, the states, colours and diatomic molecules of chlorine, bromine and iodine, why the noble gases are unreactive and their properties, the outer electrons and ions of Groups 1 and 7, why reactivity rises down Group 1 and falls down Group 7, predictions for rubidium and astatine, halogen displacement, and noble gas boiling points. | 16 |
| Transition metals | How transition metals compare with Group 1 metals in melting point, density and reactivity, ions with different charges and the Roman numerals that show them, the colours of copper and iron ions, nickel as the catalyst for margarine, and copper for water pipes. | 9 |
| Predicting reactivity from the Periodic Table | Where metals and non-metals sit, why a group reacts alike, caesium in water, the formulae of potassium iodide and calcium chloride, chlorine displacing iodine, why argon does not react, and recognising a Group 1 metal. | 11 |
| Reactivity of metals with water and acids | Why metals form positive ions when they react with water or acid, the products with acid, why potassium reacts faster than calcium, the metals that react with cold water, magnesium with steam, why copper does not react with acid while zinc and iron react slowly, ordering metals by fair tests and displacement, the temperature rise, cleaning with emery paper, and aluminium's oxide layer. | 16 |
| Tests for oxygen, hydrogen, carbon dioxide and chlorine | The tests and positive results for oxygen, hydrogen, carbon dioxide and chlorine, why the litmus paper must be damp, what turns limewater milky, telling oxygen from hydrogen with a splint, what chlorine looks and smells like and why it is tested in a fume cupboard, and identifying a gas from its test results. | 10 |
| Tests for aqueous cations and anions | Using sodium hydroxide solution to identify calcium, copper(II), iron(II), iron(III) and zinc ions by their precipitates, telling calcium from zinc with excess reagent, the acid test for carbonate ions, acidified silver nitrate for chloride, bromide and iodide ions, the barium chloride test for sulfate ions, and why acid is added first in the halide and sulfate tests. | 15 |
| Flame tests, and identifying metal ions | The wire loop and how it is cleaned, the Bunsen flame used and why, picking up a solid sample, why mixtures give unreliable results, and the flame colours of lithium, sodium, potassium, calcium and copper. | 14 |
| Identifying a species from test results | Why a cation test and an anion test are both needed, naming salts from flame colours and precipitates with sodium hydroxide, silver nitrate and barium chloride, and why silver nitrate without acid is unsafe. | 8 |
| Instrumental methods of analysis | The sensitivity, accuracy and speed of machine methods, their cost and need for trained operators and reference data, why they suit mixtures and tiny samples, and reading a mass spectrum. | 14 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
OCR GCSE Chemistry A, Foundation tier Active Recall Guide
Every topic, not just this one. 1,070 questions with their answers.