Concentration of Solutions — GCSE Chemistry Revision
Revise Concentration of Solutions for GCSE Chemistry. Step-by-step explanation, worked examples, common mistakes and exam-style practice aligned to AQA, Edexcel, OCR, WJEC, Eduqas, CCEA, Cambridge International (CIE), Pearson Edexcel International, OxfordAQA International, SQA, IB, AP.
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Go to Percentage YieldWhat is Concentration of Solutions?
Concentration tells us how much of a substance (solute) is dissolved in a certain volume of a solvent. It is usually measured in grams per decimetre cubed (g/dm³) or moles per decimetre cubed (mol/dm³). A concentrated solution has a large amount of solute in a small amount of solvent.
Board notes: Concentration calculations are a higher-tier topic for all exam boards. You must be comfortable with both g/dm³ and mol/dm³ and be able to convert between them. Titration calculations also rely heavily on this knowledge.
Step-by-step explanationWorked examples
Worked example 1: Core method
To find the concentration in mol/dm³ of a solution made by dissolving 4g of NaOH (Mr = 40) in 250 cm³ of water: 1. Moles of NaOH = 4g / 40 = 0.1 mol. 2. Volume in dm³ = 250 cm³ / 1000 = 0.25 dm³. 3. Concentration = 0.1 mol / 0.25 dm³ = 0.4 mol/dm³.
Worked example 2: Exam variation
Now change one detail in the question and keep the same structure: name the Concentration of Solutions idea being tested, show the method or evidence, then explain why it answers the command word. This helps GCSE Chemistry students avoid memorising one surface pattern.
Worked example 3: Mark-scheme check
Finish by checking the answer against marks: one point for the correct Concentration of Solutions idea, one for accurate working or evidence, and one for a precise final statement. If any step is vague, rewrite it before moving to timed practice.
Mini lesson for Concentration of Solutions
1. Understand the core idea
Concentration tells us how much of a substance (solute) is dissolved in a certain volume of a solvent. It is usually measured in grams per decimetre cubed (g/dm³) or moles per decimetre cubed (mol/dm³).
Can you explain Concentration of Solutions without copying the notes?
2. Turn it into marks
To find the concentration in mol/dm³ of a solution made by dissolving 4g of NaOH (Mr = 40) in 250 cm³ of water: 1. Moles of NaOH = 4g / 40 = 0.
Underline the method, evidence, or command-word move that would earn credit in GCSE Quantitative Chemistry.
3. Fix the likely mark leak
Watch for this mistake: Forgetting to convert volumes from cm³ to dm³. Remember that 1 dm³ = 1000 cm³, so you must divide cm³ by 1000.
Write one correction rule before doing another practice question.
Practise this topic
Jump into adaptive, exam-style questions for Concentration of Solutions. Free to start; sign in to save progress.
Mini quiz: Concentration of Solutions
Three quick checks for revision practice. They are original StudyVector prompts, not official exam-board questions.
Question 1
In one GCSE sentence, explain what Concentration of Solutions is testing.
Answer: Concentration tells us how much of a substance (solute) is dissolved in a certain volume of a solvent. It is usually measured in grams per decimetre cubed (g/dm³) or moles per decimetre cubed (mol/dm³).
Mark focus: Precise definition and topic focus.
Question 2
A Concentration of Solutions question uses an unfamiliar context. What should the answer do before adding detail?
Answer: It should name the process, variable, equation, particle model, or evidence being tested, then explain the result using precise scientific vocabulary.
Mark focus: Method selection and command-word control.
Question 3
A student makes this mistake: "Forgetting to convert volumes from cm³ to dm³. Remember that 1 dm³ = 1000 cm³, so you must divide cm³ by 1000." What should their next repair task be?
Answer: Do one Concentration of Solutions question and review the mistake type.
Mark focus: Error correction and next-step practice.
Concentration of Solutions flashcards
Core idea
What is the main idea in Concentration of Solutions?
Concentration tells us how much of a substance (solute) is dissolved in a certain volume of a solvent. It is usually measured in grams per decimetre cubed (g/dm³) or moles per decimetre cubed (mol/dm³).
Common mistake
What mistake should you avoid in Concentration of Solutions?
Forgetting to convert volumes from cm³ to dm³. Remember that 1 dm³ = 1000 cm³, so you must divide cm³ by 1000.
Practice
What is one useful practice task for Concentration of Solutions?
Answer one Concentration of Solutions question and review the mistake type.
Exam board
How should you use board notes for Concentration of Solutions?
Concentration calculations are a higher-tier topic for all exam boards. You must be comfortable with both g/dm³ and mol/dm³ and be able to convert between them.
Common mistakes
- 1Forgetting to convert volumes from cm³ to dm³. Remember that 1 dm³ = 1000 cm³, so you must divide cm³ by 1000.
- 2Confusing the terms solute, solvent, and solution. The solute is what dissolves, the solvent does the dissolving, and the solution is the final mixture.
- 3Using the wrong formula. For concentration in g/dm³, use Mass / Volume. For mol/dm³, use Moles / Volume.
Concentration of Solutions exam questions
Exam-style questions for Concentration of Solutions with mark-scheme style solutions and timing practice. Aligned to AQA, Edexcel, OCR, WJEC, Eduqas, CCEA, Cambridge International (CIE), Pearson Edexcel International, OxfordAQA International, SQA, IB, AP specifications.
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Step-by-step method
Step-by-step explanation
4 steps · Worked method for Concentration of Solutions
Core concept
Concentration tells us how much of a substance (solute) is dissolved in a certain volume of a solvent. It is usually measured in grams per decimetre cubed (g/dm³) or moles per decimetre cubed (mol/dm³…
Frequently asked questions
What is a saturated solution?
A saturated solution is one in which the maximum amount of solute has been dissolved in a solvent at a given temperature. No more solute can be dissolved.
How does temperature affect concentration?
For most solid solutes, increasing the temperature of the solvent increases the amount of solute that can dissolve, allowing for a more concentrated solution to be made.