Practical & Qualitative Analysis

Learn and apply Practical & Qualitative Analysis in the published Chemistry course sequence.

GCE A-Level H2 Chemistry 9476-2027

Learning goals

Paper 4 Skills: P, MMO, PDO, ACE
Planning: Variables, Controls, Risk
Tables, Graphs, Uncertainty
Titration Skills and Error Sources
Qualitative Analysis: Cations (Table)
Qualitative Analysis: Anions and Gases
Organic Qualitative Tests: What to Know
Qualitative Analysis Notes
Gravimetric analysis
Gas collection and measurement
Thermochemistry practical techniques
Kinetics practical techniques
Simple organic synthesis and purification

What You’ll Learn

Plan a safe, logical investigation and explain how its data answer the question.
Apply the official P, MMO, PDO and ACE skill criteria.
Record measurements and observations at justified precision, then analyse and evaluate the evidence.
Apply gravimetry, gas collection, thermochemistry, kinetics, and organic synthesis and purification techniques in unfamiliar practical contexts.
Use the supplied cation, anion, gas and organic qualitative-analysis notes without overclaiming.

Paper 4 belongs to H2 Chemistry (9476) and contributes 20% of the qualification: Planning contributes 4%, while MMO, PDO and ACE together contribute 16%. H1 8873 has no Paper 4. H3 9813 is a separate syllabus, not a successor route.

Lessons (Recommended Order)

Paper 4 Skills: P, MMO, PDO and ACE — learn the official assessment language and technique range.
Planning: Variables, Controls and Risk — turn a question into a reproducible, safe method.
Tables, Graphs and Uncertainty — present and process evidence at justified precision.
Titration Skills and Error Sources — connect volumetric technique to error direction.
Qualitative Analysis: Cations — compare colour and excess-solubility evidence.
Qualitative Analysis: Anions and Gases — follow reagent order and confirm gases.
Organic Qualitative Tests — interpret functional-group evidence and practical exclusions.
Using the Qualitative Analysis Notes — integrate the supplied tables under exam conditions.

Practical technique deep dives

Gravimetric analysis — connect precipitation, washing and constant mass to error direction.
Gas collection — choose apparatus from gas properties and the measurement needed.
Thermochemistry experiments — obtain a defensible temperature change and convert it into an enthalpy change.
Kinetics experiments — plan continuous and clock methods that support a valid rate comparison.
Organic synthesis and purification — choose and justify separation, washing, drying and purification steps.

Quick Reference

Evidence task	Official skill	What a complete response contains
design a method	Planning (P)	defined problem, logical procedure, data-use plan, risk and precautions
perform and record	Manipulation, measurement and observation (MMO)	appropriate operation, detailed observations, justified precision, anomaly recognition
organise results	Presentation of data and observations (PDO)	suitable form, effective processing, decimal places/significant figures
interpret and improve	Analysis, conclusions and evaluation (ACE)	evidence-based conclusion, prediction, significant limitation, effect and targeted improvement
qualitative analysis	MMO + ACE	reagent/condition → observation → cautious inference

The technique range includes titration, gravimetry, gas collection, thermochemistry, kinetics, inorganic and organic qualitative analysis, and simple organic synthesis/purification.

Hub Quiz

Use the Practical and QA hub quiz for fast retrieval, then complete structured Practical and QA practice to rehearse full methods, data handling and evidence-based evaluation.

After each practical, log one error under the exact skill that caused it: P, MMO, PDO or ACE. Revisit the matching lesson before the next session.

Practise

Work through questions with marking and feedback as you learn.

About 10 minutes

Questions are picked at random each time you start. You'll see the answer after each question. It's for practice only and doesn't count towards mastery.

Recent attempts

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No completed attempts are saved yet.

This check needs JavaScript to record answers. The reviewed questions are listed below for study.

In an investigation in which temperature is a controlled variable, which statement about skill areas and controls is correct?

Explaining how a significant source of error affects the result and how to reduce it is assessed under ACE, and temperature is controlled by placing the reaction vessel in a thermostatted water bath.
Explaining the effect of an error and how to reduce it is assessed under PDO, and temperature is controlled with a thermostatted water bath.
Explaining the effect of an error and how to reduce it is assessed under ACE, and temperature is controlled by doing every experiment at the same time of day.
Explaining the effect of an error and how to reduce it is assessed under MMO, and temperature is controlled with a thermostatted water bath.

A calibration graph of absorbance against concentration is a straight line through (0, 0) and (0.050 mol dm⁻³, 0.80). A sample has an absorbance of 0.52. What is its concentration?

0.0325 mol dm⁻³
0.0769 mol dm⁻³
0.0260 mol dm⁻³
0.52 mol dm⁻³

A burette is rinsed with distilled water but not with the hydrochloric acid of known concentration that is then placed in it. The acid is titrated against aqueous NaOH in the flask. What is the effect?

The acid is diluted, so the titre is larger and the calculated concentration of NaOH is too high.
The acid is diluted, so the titre is smaller and the calculated concentration of NaOH is too low.
There is no effect, because the number of moles of acid in the burette is unchanged.
The titre is larger, so the calculated concentration of NaOH is too low.

Aqueous NaOH is added dropwise and then in excess to separate solutions containing Cu²⁺, Fe²⁺ and Fe³⁺. Which set of observations is correct?

Cu²⁺: pale blue ppt, insoluble in excess; Fe²⁺: green ppt, insoluble in excess, turning brown on standing; Fe³⁺: red-brown ppt, insoluble in excess
Cu²⁺: blue ppt, soluble in excess giving a deep blue solution; Fe²⁺: green ppt; Fe³⁺: red-brown ppt
Cu²⁺: pale blue ppt; Fe²⁺: red-brown ppt; Fe³⁺: red-brown ppt
Cu²⁺: pale blue ppt; Fe²⁺: red-brown ppt; Fe³⁺: green ppt

A solution is acidified with dilute nitric acid, and aqueous silver nitrate is added, giving a pale cream precipitate that is partially soluble in aqueous ammonia. Which conclusion is correct?

Br⁻ is present.
Cl⁻ is present.
I⁻ is present.
CO₃²⁻ is present, because nitric acid was not needed.

Which test result distinguishes cyclohexene from cyclohexane correctly?

Cyclohexene decolourises orange bromine water at room temperature in the dark; cyclohexane does not.
Cyclohexane decolourises bromine water rapidly in the dark; cyclohexene does not.
Both decolourise bromine water, because both are hydrocarbons.
Cyclohexene gives an orange precipitate with 2,4-DNPH.

Which statements are correct? (1) 0.120 g of magnesium (Ar 24.3) reacting with excess hydrochloric acid gives 237 cm³ of hydrogen at r.t.p. (24.0 dm³ mol⁻¹). (2) The magnesium should be kept apart from the acid until the flask is sealed to the gas syringe, so that no hydrogen escapes. (3) A hydrogen volume lower than expected could be caused by the magnesium being coated with oxide. (4) In gravimetric analysis of sulfate as BaSO₄, failing to wash soluble impurities from the precipitate gives a calculated mass of sulfate that is too high.

(2), (3) and (4) only
(1), (2), (3) and (4)
(2) and (4) only
(3) only

In a displacement reaction in a polystyrene cup, the temperature is recorded every 30 s before and after mixing, and the cooling line after the maximum is extrapolated back to the time of mixing. Why?

To estimate the temperature rise that would have occurred with no heat loss, because the mixture loses heat to the surroundings while the reaction is still taking place.
To find the initial temperature of the solution more precisely.
To correct for the heat absorbed by the polystyrene cup, which takes most of the heat released.
Because the highest temperature recorded is always too high.

In an iodine clock experiment, the time t for the blue-black colour to appear is measured for different starting concentrations. Why is 1/t used as a measure of the initial rate?

The colour appears when a fixed small amount of iodine has formed, so the rate over that short time is proportional to 1/t while very little reactant has been used.
Because the rate is directly proportional to t.
Because 1/t is equal to the rate constant.
Because times cannot be measured accurately, so they must be inverted.

Crude ethyl ethanoate, containing ethanoic acid and sulfuric acid, is shaken with aqueous sodium carbonate in a separating funnel. Which statement is correct?

Sodium carbonate neutralises the acids, releasing CO₂, so the funnel is inverted and the tap opened often to release pressure; the ester forms the upper layer, and it is later dried with an anhydrous drying agent before distillation.
Sodium carbonate removes the ester’s impurities by reacting with the ester itself.
The ester forms the lower layer, which is run off and kept.
The funnel stays stoppered with the tap closed throughout shaking.

Practise after feedback

After a check, practise the skills it showed you need to work on.

About 10 minutes

Questions are picked at random each time you start. You'll see the answer after each question. It's for practice only and doesn't count towards mastery.

Recent attempts

History is stored only in this browser.

No completed attempts are saved yet.

This check needs JavaScript to record answers. The reviewed questions are listed below for study.

In an investigation in which temperature is a controlled variable, which statement about skill areas and controls is correct?

Explaining how a significant source of error affects the result and how to reduce it is assessed under ACE, and temperature is controlled by placing the reaction vessel in a thermostatted water bath.
Explaining the effect of an error and how to reduce it is assessed under PDO, and temperature is controlled with a thermostatted water bath.
Explaining the effect of an error and how to reduce it is assessed under ACE, and temperature is controlled by doing every experiment at the same time of day.
Explaining the effect of an error and how to reduce it is assessed under MMO, and temperature is controlled with a thermostatted water bath.

A calibration graph of absorbance against concentration is a straight line through (0, 0) and (0.050 mol dm⁻³, 0.80). A sample has an absorbance of 0.52. What is its concentration?

0.0325 mol dm⁻³
0.0769 mol dm⁻³
0.0260 mol dm⁻³
0.52 mol dm⁻³

The acid is diluted, so the titre is larger and the calculated concentration of NaOH is too high.
The acid is diluted, so the titre is smaller and the calculated concentration of NaOH is too low.
There is no effect, because the number of moles of acid in the burette is unchanged.
The titre is larger, so the calculated concentration of NaOH is too low.

Aqueous NaOH is added dropwise and then in excess to separate solutions containing Cu²⁺, Fe²⁺ and Fe³⁺. Which set of observations is correct?

Cu²⁺: pale blue ppt, insoluble in excess; Fe²⁺: green ppt, insoluble in excess, turning brown on standing; Fe³⁺: red-brown ppt, insoluble in excess
Cu²⁺: blue ppt, soluble in excess giving a deep blue solution; Fe²⁺: green ppt; Fe³⁺: red-brown ppt
Cu²⁺: pale blue ppt; Fe²⁺: red-brown ppt; Fe³⁺: red-brown ppt
Cu²⁺: pale blue ppt; Fe²⁺: red-brown ppt; Fe³⁺: green ppt

A solution is acidified with dilute nitric acid, and aqueous silver nitrate is added, giving a pale cream precipitate that is partially soluble in aqueous ammonia. Which conclusion is correct?

Br⁻ is present.
Cl⁻ is present.
I⁻ is present.
CO₃²⁻ is present, because nitric acid was not needed.

Which test result distinguishes cyclohexene from cyclohexane correctly?

Cyclohexene decolourises orange bromine water at room temperature in the dark; cyclohexane does not.
Cyclohexane decolourises bromine water rapidly in the dark; cyclohexene does not.
Both decolourise bromine water, because both are hydrocarbons.
Cyclohexene gives an orange precipitate with 2,4-DNPH.

(2), (3) and (4) only
(1), (2), (3) and (4)
(2) and (4) only
(3) only

To estimate the temperature rise that would have occurred with no heat loss, because the mixture loses heat to the surroundings while the reaction is still taking place.
To find the initial temperature of the solution more precisely.
To correct for the heat absorbed by the polystyrene cup, which takes most of the heat released.
Because the highest temperature recorded is always too high.

In an iodine clock experiment, the time t for the blue-black colour to appear is measured for different starting concentrations. Why is 1/t used as a measure of the initial rate?

The colour appears when a fixed small amount of iodine has formed, so the rate over that short time is proportional to 1/t while very little reactant has been used.
Because the rate is directly proportional to t.
Because 1/t is equal to the rate constant.
Because times cannot be measured accurately, so they must be inverted.

Crude ethyl ethanoate, containing ethanoic acid and sulfuric acid, is shaken with aqueous sodium carbonate in a separating funnel. Which statement is correct?

Sodium carbonate neutralises the acids, releasing CO₂, so the funnel is inverted and the tap opened often to release pressure; the ester forms the upper layer, and it is later dried with an anhydrous drying agent before distillation.
Sodium carbonate removes the ester’s impurities by reacting with the ester itself.
The ester forms the lower layer, which is run off and kept.
The funnel stays stoppered with the tap closed throughout shaking.

Check what I know

Start here to see which parts you already know.

About 8 minutes

Answer 10 short questions. It shows what to work on next and doesn't count towards mastery.

Recent attempts

History is stored only in this browser.

No completed attempts are saved yet.

This check needs JavaScript to record answers. The reviewed questions are listed below for study.

A student plans to find how the solubility of potassium nitrate varies with temperature by dissolving different masses of KNO₃ in 10.0 cm³ of hot water and recording the temperature at which crystals first appear on cooling. Which statement is correct?

The independent variable is the mass of KNO₃ in 10.0 cm³ of water, the dependent variable is the temperature at which crystals appear, the volume of water is controlled, and hot solutions are handled with tongs to avoid scalds; writing this method is assessed as Planning (P).
The independent variable is the temperature at which crystals appear, and the dependent variable is the mass of KNO₃.
The variables are identified correctly, but writing this method is assessed under Analysis, Conclusion and Evaluation (ACE).
The volume of water need not be controlled, because solubility is a fixed property of potassium nitrate.

A titre of 24.50 cm³ is found from an initial and a final burette reading, each with an uncertainty of ±0.05 cm³. What is the percentage uncertainty in the titre?

0.41 %
0.20 %
0.0041 %
0.10 %

A student records these titres: rough 25.40 cm³, then 24.85 cm³, 24.60 cm³ and 24.70 cm³. Which mean titre should be used in the calculation?

24.65 cm³
24.72 cm³
24.89 cm³
24.60 cm³

Aqueous NaOH is added dropwise and then in excess to an unknown solution, giving a white precipitate that dissolves to a colourless solution. Aqueous NH₃ added dropwise and then in excess gives a white precipitate that does not dissolve. Which record is correct?

Observations: white ppt, soluble in excess NaOH(aq) giving a colourless solution; white ppt, insoluble in excess NH₃(aq). Inference: Al³⁺ is present; Zn²⁺ is absent.
Observations as recorded; inference: Zn²⁺ is present.
Observation: Al³⁺ present, because the precipitate dissolved in excess NaOH(aq).
Observations as recorded; inference: Ca²⁺ is present.

A solution may contain CO₃²⁻ or SO₄²⁻. Adding dilute nitric acid gives no effervescence; aqueous barium nitrate is then added, giving a white precipitate. Which deduction is correct?

SO₄²⁻ is present and CO₃²⁻ is absent: the acid shows there is no carbonate, and a white precipitate of BaSO₄ forms in the acidified solution.
CO₃²⁻ is present, because BaCO₃ is a white precipitate.
Both CO₃²⁻ and SO₄²⁻ are present.
Neither ion can be identified, because barium ions precipitate many anions.

Which pair of tests, used together, distinguishes propan-1-ol, propanal and propanone from one another?

2,4-DNPH, then Tollens’ reagent
2,4-DNPH only
Tollens’ reagent, then Fehling’s solution
Aqueous sodium carbonate, then Tollens’ reagent

Which statements are correct? (1) To find x in MgSO₄·xH₂O, the sample is heated, cooled and weighed repeatedly until two consecutive masses agree, so that all the water has been removed. (2) If 2.50 g of MgSO₄·xH₂O leaves 1.22 g of anhydrous MgSO₄ (Mr 120.4), then x = 7. (3) Hydrogen can be collected over water or in a gas syringe to measure its volume, because it is only slightly soluble in water. (4) Carbon dioxide volumes are measured most accurately by collecting the gas over water.

(1), (2) and (3) only
(1), (2), (3) and (4)
(2) and (3) only
(1) only

25.0 cm³ of 2.00 mol dm⁻³ HCl is mixed with 25.0 cm³ of 2.00 mol dm⁻³ NaOH in a polystyrene cup, and the temperature rises by 13.2 °C. Assuming a density of 1.00 g cm⁻³ and c = 4.18 J g⁻¹ K⁻¹, what is the enthalpy change of neutralisation?

−55.2 kJ mol⁻¹
−27.6 kJ mol⁻¹
−110 kJ mol⁻¹
+55.2 kJ mol⁻¹

A gas syringe records the volume of gas against time. The tangent to the curve at t = 0 passes through (0 s, 0 cm³) and (20 s, 50 cm³); the curve itself reaches 50 cm³ at 40 s. What is the initial rate?

2.5 cm³ s⁻¹
1.25 cm³ s⁻¹
0.40 cm³ s⁻¹
50 cm³ s⁻¹

Ethanol is oxidised to ethanoic acid using excess acidified potassium dichromate(VI). Which procedure is correct?

Heat under reflux so that volatile ethanol and ethanal condense and return to the flask until oxidation to ethanoic acid is complete, then distil to separate the acid.
Distil the mixture as soon as it is heated.
Heat the mixture in an open beaker.
Heat under reflux with a stopper fitted in the top of the condenser.

Check my progress

When you feel ready, answer on your own to show what you can do.

About 10 minutes

Answer 10 questions. You'll see your score, the answers and explanations at the end. Your result can count towards your course progress.

Recent attempts

History is stored only in this browser.

No completed attempts are saved yet.

Check again

After practising what your progress check showed, check those skills again.

About 10 minutes

Answer 10 questions. You'll see your score, the answers and explanations at the end. Your result can count towards your course progress.

Recent attempts

History is stored only in this browser.

No completed attempts are saved yet.

Review

Come back later to see whether your learning has lasted.

About 10 minutes

Answer 10 questions. You'll see your score, the answers and explanations at the end. A scheduled review counts towards your course progress only when it is due.

Recent attempts

History is stored only in this browser.

No completed attempts are saved yet.

Using practical skills across the course

Use this family throughout the H2 course rather than leaving it until the final Paper 4 revision block.

Weak method logic → Planning.
Weak precision or observations → MMO and Titration.
Weak tables, graphs or uncertainty → PDO and Data.
Generic limitations or unsupported conclusions → ACE.
Slow table use or inference-only answers → the three QA lessons.

Return to H2 Chemistry to choose the content topic behind the practical context, or use the Exam Skills hub for command-word practice.

Practical & Qualitative Analysis

What You’ll Learn

Lessons (Recommended Order)

Practical technique deep dives

Quick Reference

Hub Quiz

Practise

Practice complete

Your answers

Practise after feedback

Practice complete

Your answers

Check what I know

Starting check complete

Your answers

Check my progress

Progress check complete

Your answers

Check again

Progress check complete

Your answers

Review

Review complete

Your answers

Using practical skills across the course