Lesson Plan

4. Outline the reactions of acids with metals

KS3-15-04

Intent

Learning Intention

  • Understand the concept of the reaction between acids and metals; define the reaction between acids and metals and identify when a chemical reaction involves this reaction. 
  • Identify the reactivity series of metals, including their relative positions in the series and their reactions with acids
  • Develop problem-solving skills related to the reaction between acids and metals; apply knowledge of the reaction between acids and metals to solve problems related to chemical reactions involving acids and metals

National Curriculum

  • Learn that acids react with some metals to produce salts and hydrogen, and with carbonates to produce carbon dioxide
  • Learn that alkalis react with acids to produce salts and water

Working Scientifically

  • Select, plan and carry out the most appropriate types of scientific enquiry to test predictions, including identifying independent, dependent and control variables. Use appropriate techniques, apparatus, and materials during fieldwork and laboratory work, paying attention to health and safety

Learning Outcomes

  • Identify and write the word equation for the reaction of acids with metals
  • Predict the products of the reaction of magnesium and iron with hydrochloric acid
  • Carry out a simple experiment to observe the reaction of magnesium and iron with hydrochloric acid

Resources

Resources: 1M hydrochloric acid, pipette, metal sample: magnesium, iron, lead, zinc, aluminium, splint, candle matches, test tubes and rack and a boiling tube. 

Core Handout: Card cut-outs to accompany the 'Making Salts' activity and instructions for the reactivity activity. 

Rocket words

  • sulphuric acid
  • metal
  • hydrogen
  • salt
  • squeaky pop test

Implementation

Prior Learning 

Ensure that students have a good understanding of the properties of metals and non-metals, including their physical properties, reactivity and conductivity. Prior knowledge of the properties of acids and bases, including pH, can be helpful in understanding the reactions of acids with metals.

Starter

Recap the previous lesson on neutralisation reactions, focusing on the concept of acids and their properties. Ask the students to identify and write down the definition of a metal. Review the concept of chemical reactions and how they occur. 

Main Teaching

Introduce the concept of acid-metal reactions and explain how they occur. Provide examples of acid-metal reactions, including the reaction of hydrochloric acid with magnesium and iron. Demonstrate the experiment to observe the reaction of magnesium and iron with hydrochloric acid, step by step. Explain how to write the word equation for the reaction of hydrochloric acid with magnesium and iron, and the balanced chemical equation for the reaction with magnesium. Allow students to work in pairs to carry out the experiment using the magnesium and iron provided, and record their observations and results. Discuss the results and explain the products of the reaction of magnesium and iron with hydrochloric acid. Reinforce the importance of safety precautions when working with chemicals. 

Career Film: Anna works as a Graduate Programmes Consultant as part of the Human Resources Team for BP.

Expert Film: Watch Heather and Sam produce some hydrogen-filled bubbles through the reaction of a metal and an acid.

Mission Assignment

Acids and Metals

The students will be comparing the reactivity of different metals with acid.

Student Method

  1. Pipette 3 cm³ 0.1M hydrochloric acid into a test tube in a rack.
  2. Drop in a small piece of magnesium ribbon into the test-tube and cover with an inverted boiling tube.
  3. Observe the reaction taking place. Once the reaction is complete, remove the boiling tube while keeping it inverted and place a lit splint over the end of the boiling tube. If there is a "squeaky pop" then hydrogen gas is present.
  4. Repeat this process for other metals.

Once completed, rank the metals in order of reactivity, justifying your order.

Making salts card sort

Cut out the acid and metal cards from the handout. Make one pile for the metals and one pile for the acids with the writing face down. Shuffle the piles and then randomly select a piece of paper from each pile and, as quickly as possible, name the salt that would be formed. To extend this task, the students could also write down the balanced chemical equation for the reaction between the randomly chosen metal and salt.

This could also be done competitively in larger groups/teams with a simple scoring system for fastest to name the salt formed.

Differentiated tasks (Support/Challenge)

Support: 

  • Simplify the language used when explaining the concept of acid-metal reactions.
  • Provide step-by-step guidance when carrying out the experiment, including the use of the test tubes and bunsen burner.
  • Use visuals such as pictures and diagrams to help illustrate the topic.
  • Provide extra time for students to complete their work and ask questions.

Stretch: 

  • Provide a clear explanation of the concept of acid-metal reactions and how they occur.
  • Use practical demonstrations and examples to help reinforce the topic.
  • Challenge the students to predict the results of the experiment before carrying it out.
  • Encourage students to work in pairs or small groups to discuss and explain the concept of acid-metal reactions and their applications.
  • Provide extra challenge questions for students who demonstrate a good understanding of the topic.

Challenge: 

  • Provide a more in-depth explanation of the topic, including the scientific principles behind acid-metal reactions.
  • Encourage students to explore the topic further by researching and presenting on a specific aspect of acid-metal reactions and their applications.
  • Provide opportunities for students to design their own experiments related to acid-metal reactions and to explain their methodology and results.
  • Encourage independent thinking and critical analysis through open-ended questions and discussions.

Impact & Assessment Opportunities

Plenary

Ask the students to share their observations and results from the experiment. Review the learning objectives and ask students to reflect on whether they have achieved them. Preview the next lesson on acid-base titrations, which will build on the concepts learned in this lesson. 

Teacher Mastery

For the reaction of an acid and a metal we would expect there to be heat released (this is a physical change for the reaction and could be measured using a thermometer). We would also expect to see bubbles forming at the metal surface due to the production of hydrogen gas. How quickly the reaction proceeds (or how vigorously the reaction will bubble) depends on many factors, such as the reactivity of the metal.

For a reaction with a particular acid, an approximate reactivity series for metals is (from most reactive to least reactive): Potassium > Sodium > Calcium > Magnesium > Aluminium > Zinc > Iron > Tin > Lead > Copper > Silver > Gold > Platinum.

A laboratory test for hydrogen can be performed using a burning wooden splint. The burning wooden splint goes 'pop' if it is placed in a test tube filled with hydrogen (the flame ignites the hydrogen which makes a loud sound from burning explosively).

Salts produced from the reactions of acids and metals are named in the following way: the first part of the name derives from the metal that was used and the second part of the name derives from the acid that was used. Salts derived from hydrochloric acid (HCl) have chloride as the second part of their name, salts derived from sulphuric acid (H₂SO₄) have sulphate as the second part of their name and salts derived from nitric acid (HNO₃) have nitrate as the second part of their name. An example of a common salt is sodium chloride (NaCl) (table salt).

Other, less common, acids could also be used in the discussion. For example, salts derived from hydrobromic acid (HBr) have bromide as the second part of their name and salts derived from phosphoric acid (H₃PO₄) have phosphate as the second part of their name.