Use solutions of known solution acidity/alkalinity in order to deduce a Exploring: obtained from Using red cabbage as an colour chart for an indicator. indicator this process is Explain why litmus is purple in neutral A two-part practical: students first then used to solutions. extract the colour from red cabbage test a variety of Exceeding leaves by crushing, dissolving and household Evaluate the effectiveness of different filtering. The solution obtained from chemical indicators. this process is then used to test a substances, variety of household chemical allowing substances, allowing students to students to classify these as acids or alkalis. classify these as acids or alkalis. Explaining: Laboratory indicators Set up a row of test tubes in pairs, with a different indicator in each pair. Demonstrate what happens when the indictors are mixed together. Plenary: Thinking skills Odd One Out: vinegar, orange juice. (Possible answers: water is the only neutral substance or not an acid.) Lesson 7Fc: Acidity and alkalinity Learning objectives Exemplar teaching activities Differentiation Resources skills Practical skills Developing Starter: How strong? Exploring: Resources n/a Students test Describe how universal indicator is Introduce the idea of a numerical Testing the pH of from 7Fc substances used to distinguish between acidic, scale to indicate how acidic or alkaline substances Exploring universal alkaline and neutral solutions. a substance is, by comparing two Ask students to Science. indicator Describe the main features of the pH different dilutions of hydrochloric acid write a short solution or scale (numbered scale that shows how using litmus and marble chips. paragraph about paper. acidic or alkaline a solution is, with why a numerical solutions below pH 7 being acidic, Exploring: Testing the pH of scale is Have prepared those above pH 7 being alkaline and substances preferable based a set of test those at pH 7 being neutral). on subjective tubes with
Use solutions of known acidity/alkalinity in order to deduce a colour chart for an indicator. Explain why litmus is purple in neutral solutions. Exceeding Evaluate the effectiveness of different indicators. Exploring: Using red cabbage as an indicator A two-part practical: students first extract the colour from red cabbage leaves by crushing, dissolving and filtering. The solution obtained from this process is then used to test a variety of household chemical substances, allowing students to classify these as acids or alkalis. Explaining: Laboratory indicators Set up a row of test tubes in pairs, with a different indicator in each pair. Demonstrate what happens when the indictors are mixed together. Plenary: Thinking skills Odd One Out: vinegar, orange juice. (Possible answers: water is the only neutral substance or not an acid.) solution obtained from this process is then used to test a variety of household chemical substances, allowing students to classify these as acids or alkalis. Lesson 7Fc: Acidity and alkalinity Learning objectives Exemplar teaching activities Differentiation Resources skills Practical skills Developing Describe how universal indicator is used to distinguish between acidic, alkaline and neutral solutions. Describe the main features of the pH scale (numbered scale that shows how acidic or alkaline a solution is, with solutions below pH 7 being acidic, those above pH 7 being alkaline and those at pH 7 being neutral). Starter: How strong? Introduce the idea of a numerical scale to indicate how acidic or alkaline a substance is, by comparing two different dilutions of hydrochloric acid using litmus and marble chips. Exploring: Testing the pH of substances Exploring: Testing the pH of substances Ask students to write a short paragraph about why a numerical scale is preferable based on subjective Resources from 7Fc Exploring Science. n/a Students test substances universal indicator solution or paper. Have prepared a set of test tubes with
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