A-Level Chemistry Revision — Acids & Bases (A-Level)
Revise Acids & Bases (A-Level) for A-Level Chemistry with a topic explanation, worked example and common mistakes. Check the board notes for specification differences.
At a glance
- What StudyVector is
- An exam-practice platform with board-aligned questions, explanations, and adaptive next steps.
- This topic
- Acids & Bases (A-Level) in A-Level Chemistry: explanation, examples, and practice links on this page.
- Who it’s for
- Students revising A-Level Chemistry for UK exams.
- Exam boards
- Check your course page and the topic board notes for supported specifications.
- Free plan
- Sign up free to use tutor paths and feedback on your answers. Free access is Free daily revision · No card required. Pricing
- What makes it different
- Syllabus-shaped practice and progress tracking—not generic AI answers.
This page includes a topic explanation and a worked example. Check your course for current practice coverage.
Next in this topic area
Next step: Electrode Potentials
Continue in the same course — structured practice and explanations on StudyVector.
Go to Electrode PotentialsTopic explanation
What is Acids & Bases (A-Level)?
A-Level Chemistry introduces the Brønsted-Lowry theory of acids and bases, where acids are proton donors and bases are proton acceptors. The concept of conjugate acid-base pairs is central. The topic delves into pH calculations for strong and weak acids and bases, using the acid dissociation constant, Ka, and the ionic product of water, Kw. Buffer solutions, which resist changes in pH, are also a key area of study, vital for biological systems and chemical applications.
Board notes: All boards require proficiency in pH, Ka, and buffer calculations. AQA often includes questions involving titration curves, asking students to identify buffer regions and choose appropriate indicators. Edexcel may focus on the application of buffers in biological systems, such as the carbonic acid-hydrogencarbonate buffer in blood. OCR frequently tests the calculation of pH for a variety of acidic and basic solutions, including diprotic acids.
Step-by-step explanationWorked examples
Worked example
Calculate the pH of a 0.100 mol dm-3 solution of ethanoic acid (CH3COOH), given that its Ka = 1.74 x 10^-5 mol dm-3. Step 1: Write the Ka expression: Ka = [H+][CH3COO-]/[CH3COOH]. Step 2: Make the approximation that [H+] = [CH3COO-] and that the equilibrium concentration of [CH3COOH] is approximately the initial concentration (0.100 M). Step 3: Rearrange to find [H+]: [H+] = sqrt(Ka * [CH3COOH]) = sqrt(1.74e-5 * 0.100) = 1.32 x 10^-3 mol dm-3. Step 4: Calculate pH: pH = -log10([H+]) = -log10(1.32e-3) = 2.88.
Practise this topic
Start with low-focus cards for Acids & Bases (A-Level), then move into full exam-style practice when you want the heavier session.
Common mistakes
- 1Confusing strong/weak with concentrated/dilute. A strong acid fully dissociates in water, whereas a weak acid only partially dissociates. Concentration refers to the amount of acid dissolved in a given volume of water.
- 2Incorrectly setting up Ka expressions. The expression for a weak acid HA is Ka = [H+][A-]/[HA], with concentrations being the equilibrium values, not the initial ones.
- 3Assuming the pH of a neutral solution is always 7. The pH of a neutral solution is only 7 at 298K (25°C). Since the autoionisation of water is endothermic, Kw increases with temperature, and the pH of a neutral solution decreases (e.g., to 6.77 at 313K).
Acids & Bases (A-Level) exam questions
Check the available question sets for Acids & Bases (A-Level). Use your course and exam board to confirm which practice is relevant.
Acids & Bases (A-Level) exam questionsGet help with Acids & Bases (A-Level)
Get a personalised explanation for Acids & Bases (A-Level) from the StudyVector tutor. Ask follow-up questions and work through problems with step-by-step support.
Open tutorSave your progress in Acids & Bases (A-Level)
Start a free account for low-focus question cards, feedback and Play routes across available topics. Free daily limits apply; no card required.
Continue your revision
A public question for Acids & Bases (A-Level) is still being reviewed. Your course page shows the topics currently available for practice.
Continue with Acids & Bases (A-Level)
Create a free account to keep your course choice and save your practice progress.
Start free low-focus cardsAlready have an account? Log in
Frequently asked questions
What is a buffer solution?
A buffer solution is a mixture that resists changes in pH when small amounts of acid or alkali are added. It is typically made from a weak acid and its conjugate base (e.g., ethanoic acid and sodium ethanoate), or a weak base and its conjugate acid.
How does a buffer solution work?
It contains a reservoir of the weak acid (to react with added alkali) and its conjugate base (to react with added acid). These reactions remove the added H+ or OH- ions, thus keeping the pH of the solution relatively stable.