Lesson Plan of Properties and Uses of Acids (Acids, Alkalies and Salts)
General Science Grade VIII
Students’ Learning Outcomes
· Define acid in its own words.
· Describe the properties of acids.
· Explain the uses of acids in daily life.
Information for Teachers
· Acids are the chemical substances which give H’ ion in aqueous solution.
· Acids have sour taste.
· Hydroelectric acid is found in our stomach.
· Citric acid in vitamin c.
· They change blue litmus paper to red.
· Acids react with bases to form salt and water (neutralization)
· Acidic solutions are good electrical conductors. Due to ionization in solution they form free mobile ions which conduct electricity.
· Acids are used in the production of metal, paper, paint, detergent and fertilizers.
· Nitrite acid is used to make fertilizers like ammonium nitrate. Sulfuric acid is used as home cleaner and also in car batteries.
· Source of Acids:
· Aqua Regina can dissolve gold. It is made by adding one part concentrated nitrite acid to three parts of concentrated hydroelectric acid.
· Sulfuric acid is used in almost all car batteries and also known as “Oil of Vitriol”.
· The ‘fizz’ in soft drinks is produced by adding carbolic acid (H2 CO3)
· Acetic acid is extensively used in food industry as a preservative.
· Acid have a pH less than 7.
Material / Resources
For each group you require: blue litmus papers, vinegar, beakers, lemon juice, water, stirrer, and pH
Worm up activity
· Write the word, “Acidic solution”, on the board and ask students to give their ideas about it.
· Write all their ideas on the board.
· Divide students in groups and instruct them to:
o Dip blue litmus paper in vinegar.
o Observe what happens to the blue litmus paper.
· Now ask these questions:
o What is the change in color of blue litmus paper?
o Vinegar is an edible acid; can you predict its taste? (Don’t allow children to taste anything in laboratory)
· After getting students response, conclude the activity by telling them that vinegar changes the blue litmus paper into red because it is acidic in nature & it is sour in taste.
· Divide students in pairs and instruct them to :
o Take small amount of lemon juice in beaker A and water in beaker B.
o Dip blue litmus paper in both the solutions.
o Observe what happens to the blue litmus on dipping in the two solutions.
· Now ask the following questions:
o Did you see any change in the color of blue litmus paper?
o What is the color difference of two litmus papers dipped in different solutions in beaker A and B?
· Conclude the activity by telling that beaker ‘A’, turned blue litmus paper into red as lemon juice is acidic in nature while beaker ‘B’, doesn’t affect the blue litmus paper because contains water that is neutral.
· Divide students in small groups and instruct them to:
o Take two beakers, label them A and B .
o Half fill the two beakers with water.
o Add one teaspoon of vinegar in beaker A.
o Add 5 teaspoons of vinegar in beaker B.
o Stir these mixtures.
o Dip the strips of pH paper in the two solutions.
o Note the pH values of both the solutions.
· Now, ask the following questions:
o What are the pH values of two solutions?
o Which of the two solutions (A and B) has smaller pH value and why?
· Conclude the activity by telling the students that the solution in beaker ‘A’, is dilute and solution in beaker ‘B’ is concentrated. PH value of concentrated solution is less than pH value of dilute solution.
Sum up / Conclusion
· Teacher can conclude the lesson by telling children that they leant about:
o Acids give H’ ions in aqueous solutions and turn blue litmus paper red.
o Acids are of great use in fertilizers, car batteries and industries etc.
o Acidic solutions are good electrical conductors in solutions.
· Why does acid rain destroy buildings especially those made from limestone (a form of calcium carbonate)?
(Expected response: Acid rain contains oxides of sulfur (SO2), which forms sulfuric acid on reacting with water. Acids have a corrosive effect and can cause limestone building to dissolve).
· Name a fruit and a vegetable that is acidic in nature. How did you guess it?
(Expected response: Fruit: Oranges Vegetable: Lemon. They have sour taste.)
· Haynes has some transparent liquid, which she claims to be an acid. How can you prove or disprove her claim?
(Expected response: Dip a blue litmus paper in transparent liquid. it becomes red which proves that it is an acid)
· Ask the students to prepare a booklet on acids. The booklet should contain colorful pictures related to the sources, uses and properties of any two acids of your choice.