ASEI Lesson Plan Format

Lesson Note on Chemistry

Subject: Chemistry

Theme: Acids Bases & Indicators

Topic: Acids Bases & Indicators II

Sub Topic: Reactivity Series of Metals using Dilute HCl

Date: dd/mm/yyyy

Class: S.S.S 2

Duration: 35 Minutes

No of Learners: 30

Learning Objectives:

By the end of the lesson learners should be able to:
  1. Arrange the metals A, B, and C in order of their reactivity after reacting with dilute HCl

  2. Metal A reaction with dilute acids was rapid, bubbles and hissing sounds are produced, the test tube becomes warm and a colourless solution was formed. Metal A is probably Magnesium.

    Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)↑

    Metal B reaction with dilute acids was more rapid than metal A, bubbles are produced, the test tube was hot/warm than that of metal A and a colourless solution was form. Metal B is probably Calcium.

    Ca(s) + 2HCl(aq) → CaCl2(aq) + H2(g)↑

    Metal C reaction with dilute acids was much less vigorous i.e very slow, with much smaller bubbles produced and pale green solutions formed when reaction went to completion, a yellow showery sparks and black solid were produced when the heat was applied. Metal C is probably Iron.

    Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g)↑

    Reactivity of Metals A, B, and C with dilute HCL is

    MOST REACTIVE Metal B → LESS REACTIVE Metal A → LEAST REACTIVE Metal C

  3. Define a reactivity series.

  4. The reactivity series of metals is a chart showing metals in order of decreasing reactivity. In general, the more reactive a metal is:

    • the more vigorous its reactions are
    • the more easily it loses electrons in reactions to form positive ions (cations)

Rationale:

Reactions of metals and acids are very important in everyday life. The speed of a reaction is crucial, for example, in industrial processes where a product ought to be obtained as fast and as cheaply as possible for economic reasons. Do reactions take place at the same speed? This activity will help learners to answer this question.

Prerequisite/ Previous knowledge:

Acids, metals and reactions of dilute acids with metals and the products, writing and balancing chemical reaction.

Learning Materials:

Four Test tubes per group, dilute hydrochloric acid, rubber bands, balloons, metal powder labelled as A, B and C, Magnesium ribbon

Reference Materials:

New School Chemistry. By Ababio



Lesson Development:

STAGE
TEACHER'S ACTIVITY
LEARNER'S ACTIVITY
LEARNING POINTS
INTRODUCTION
full class session (5mins)
The teacher asks the learners to write and balance the following reaction:
  1. Mg(s) + H2SO4(aq)
  2. Ca(s) + H2SO4(aq)
  3. Ca(s) + HCl(aq)
  4. Mg(s) + HCl(aq)
  5. Na(s) + H2O(l)
  6. CaCO3(s) + HCl(aq)
  7. Ca(OH)2(s) + HCl(aq)
  8. Fe(s) + HCl(aq)
The learners attempted the teacher's questions:
  1. Mg(s) + H2SO4(aq) → MgSO4(aq) + H2(g)
  2. Ca(s) + H2SO4(aq) → CaSO4(s) + H2(g)
  3. Ca(s) + 2HCl(aq) → CaCl2(aq) + H2(g)
  4. Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
  5. 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
  6. CaCO3(s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l)
  7. Ca(OH)2(s) + 2HCl(aq) → CaCl2(aq)+ 2H2O(l)
  8. Fe(s) + 2HCl(aq) → FeCl2(aq) + H2 (g)
Linking previous knowledge with the lesson
STEP 1
10 mins.
Development
The teacher writes on the whiteboard the topic and sub-topics.

Activity 1

Teacher shown learners the metal X and asked learners to identify its name.
The learners identify its name.
Magnesium ribbon
Pre-requisite knowledge
The teacher reacted the Metal X with acid and ask learners to state the observations. Learners observe the reaction of the metal with the acid and state the observations. (Hands and Minds-on activity)
Learners identify the products formed.
Learners suggest whether different metals react rapidly with acids. (Minds-on activity)
Observation of the reaction
  • Bubbles and hissing sounds are produced, test tube becomes warm.
  • Metals react with acid to produce Salt and Hydrogen gas.

Predictions

STEP 2
10 mins.

Activity 2

Teacher explains the purpose of the activity as to investigate how fast metals A, B, and C react with dilute HCl.
The teacher explains the procedure and precautions to be taken care of by the learners.

Material/apparatus

  • Three test tubes
  • 10 ml measuring cylinder,
  • Dilute hydrochloric acid,
  • Balloons,
  • Rubber bands,
  • Metal powder labelled A, B and C,
  • Stop Watch

PROCEDURE:

  1. You are provided with three test tubes labelled A, B and C respectively. Using a 10 ml measuring cylinder provided, measure 8 cm3 of dilute hydrochloric acid and add into test tubes A, B and C.
  2. Put a spatula end full of metal powder labelled A, B and C into Balloons A, B and C respectively as shown below.


  3. Tie the mouth of each balloon to the mouth of a test tube using a rubber band and ensure that acid and the metal do not mix at this stage.


    Precaution: Make sure no acid spills on your skin or clothes.
  4. Simultaneously, lift the bottoms of the balloons so that the metals flow down into the test tube and react with the acid.
  5. Observe the test tubes and balloons for 5 minutes.

Learners go through the instructions written in the paper to familiarise themselves with the activities and collect apparatus/chemicals and do the experiment. (Hands-on activity).

Learners discuss and record the observations in their exercise books. (Minds-on activity)


Cautions: Handling of the acid.

Preparation of the experiments


Meniscus of measuring cylinder

STEP 3
(5 mins)
The teacher goes around to check on what learners are doing and assist where necessary. Learners arrange the metal A, B and C in the order of the speed of reaction.
Learners report on their observations and the order of the metals on the chalkboard.
Observation and group discussions

  1. Test tube B produced more bubbles and hissing sounds and became warm.
  2. Balloon B inflated most followed by A.
  3. Recording the observations
  4. The most reactive metal is B while the least is C.

STEP 4
5 mins
The teacher asks learners to identify Metals A, B, and C base on their observations. Learners identify Metals A, B, and C:

Metal A reaction with dilute acids was rapid, bubbles and hissing sounds are produced, the test tube becomes warm and a colourless solution was formed. Metal A is probably Magnesium.


Metal B reaction with dilute acids was more rapid than metal A, bubbles are produced, the test tube was hot/warm than that of metal A and a colourless solution was formed. Metal B is probably Calcium.


Metal C reaction with dilute acids was much less vigorous i.e very slow, with much smaller bubbles produced and pale green solutions formed when reaction went to completion, a yellow showery sparks and black solid were produced when the heat was applied. Metal C is probably Iron.

Interpretation of the observation on the reactions
EVALUATION
3mins
The teacher asks questions to the learners to evaluate the lesson.
  1. The reaction of metal with acid.
  2. Definition of Reactivity series
  3. Which metal will produce a large amount of hydrogen gas and give a reason.
  1. When a metal reacts with dilute acid, salt and hydrogen are formed.
  2. Metals react at different easiness with acids.
  3. Reactivity series: list of metals/elements in order of their reactivity
  4. Metal B test tube where most bubbles are seen and the largest expansion of balloon indicates that the largest volume of Hydrogen gas was produced and the fastest reaction took place.
Asking the learners questions to assess the achievement of the set objectives.
CONCLUSION
2mins
The teacher guides the learners so that they come up with the concepts from the observations drawn. (Bridging the activities to the concept). Metal B reacts faster than metal A and C in a given time. Application: expansion of the concept
ASSIGNMENT
  1. What did you observe to show that a gas was produced?
  2. Name and explain how that gas is tested in a chemistry laboratory
  3. Write a word equation on the reaction between the dilute hydrochloric acid and Zinc metal
Learners answer other questions. Improving their level of understanding on Reactivity Series of Metals using dilute HCl.