Year 7 Acids and Alkalis Worksheet - Intermediate

Year 7 Acids and Alkalis worksheet for Year 7 (Key Stage 3 / Year 7-9 (Ages 11-14)). Intermediate level science practice, aligned to the UK National Curriculum. Print-ready with answer key included.

Science•Key Stage 3 / Year 7-9 (Ages 11-14)•Acids and Alkalisintermediate

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Acids and Alkalis: pH, Reactions and Safety

Year 7 Science · Ages 11–12 · Intermediate

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Instructions: Work through each activity and use the information provided to support your answers. Write clearly in each answer box; include units or scientific terms where appropriate. For written explanations, use complete sentences.

The pH Scale and Indicators

Use the pH values and indicator information to answer each question. Remember: pH 7 is neutral, values below 7 are acidic, and values above 7 are alkaline. Universal indicator changes colour across the pH scale.

1. A solution has pH 3. Is it acidic, neutral or alkaline?

2. A solution has pH 7. What does this tell you about the solution?

3. A solution has pH 11. Is it acidic, neutral or alkaline?

4. Universal indicator is green in a sample. What is the sample's approximate pH?

Comparing Strong and Weak Acids

Use the particle descriptions to distinguish acid strength from acid concentration. At this level, a strong acid is described as ionising more completely in water than a weak acid. Answer using the evidence in each question.

1. In water, Acid A ionises almost completely, while Acid B ionises only partly. Which acid is strong?

2. Two solutions have the same concentration. One contains a strong acid and the other a weak acid. Which is expected to have the lower pH?

3. Does the word “strong” mean that an acid solution must be concentrated? Answer yes or no and give one reason.

4. A student says, “A weak acid cannot be hazardous.” Explain why this is not a safe conclusion.

Neutralisation Reactions

Complete each response using the idea that an acid and an alkali react to form a salt and water. For the word equations, name the salt formed from the acid and the alkali.

1. Complete the general word equation: acid + alkali → ___ + water.

2. Hydrochloric acid reacts with sodium hydroxide. Name the salt formed.

3. Sulfuric acid reacts with potassium hydroxide. Name the salt formed.

4. A gardener adds lime to acidic soil. Explain how this can help the soil become less acidic.

Acids and Alkalis in Everyday Life

Read the data, then answer the questions below. The pH values are approximate; products can vary. Use the table rather than assuming that every product in a category has exactly the same pH.

Sample	Approximate pH	Type
Lemon juice	2	Acidic
Vinegar	3	Acidic
Pure water	7	Neutral
Soap solution	10	Alkaline
Household bleach	12	Alkaline

1. Which sample in the table is most acidic?

2. Which sample is closest to neutral?

3. Name the two alkaline samples listed.

4. Give one everyday use of an acid or an alkali, and identify which it is.

Working Safely with Hazardous Chemicals

Choose the safest response to each situation. Treat unknown chemicals as potentially hazardous and follow your teacher’s instructions and the laboratory risk assessment.

1. A bottle is labelled “corrosive”. What should you do before handling it?

2. A chemical splashes onto your skin. What is the safest first action?

3. Why should you never taste a laboratory chemical?

4. You find an unlabelled container. What should you do?

Answer Key

Activity 1: 1. Acidic ; 2. Neutral ; 3. Alkaline ; 4. Approximately pH 7

Activity 2: 1. Acid A ; 2. The strong-acid solution ; 3. No; strength describes how completely the acid ionises, not how concentrated the solution is ; 4. Weak acids can still be hazardous, especially if concentrated or used improperly; follow safety instructions

Activity 3: 1. Salt ; 2. Sodium chloride ; 3. Potassium sulfate ; 4. Lime is alkaline and neutralises some of the acid in the soil

Activity 4: 1. Lemon juice ; 2. Pure water ; 3. Soap solution and household bleach ; 4. Answers vary; for example, vinegar is an acid used in cooking, or soap solution is alkaline and used for cleaning

Activity 5: 1. Follow the safety instructions and wear required protection ; 2. Tell the teacher and rinse the area with plenty of water ; 3. It might be hazardous ; 4. Do not use it; tell the teacher