2021-22 GRADE 7 A SCIENCE CH PHYSICAL AND CHEMICAL CHANGES (TOPICS TAUGHT AND HOMEWORK)

 2021-22 SCIENCE CH  PHYSICAL AND CHEMICAL CHANGE

(TOPICS TAUGHT AND HOMEWORK)






DATE: 13/8/2021

GRADE: 7 A

CHAPTER: PHYSICAL AND CHEMICAL CHANGES

TOPICS TAUGHT: 

REVISED THE TOPICS OF CHANGES AROUND US

STATES OF MATTER,PROPERTIES,SOLUTE,SOLUTION,SOLVENT,SATURATED SOLUTION, PHYSICAL CHANGE

HOMEWORK: FIND MORE EXAMPLES OF PHYSICAL CHANGES AND COMPLETE THE TUNE IN GIVEN IN T.B


DATE: 16/8/2021

GRADE: 7 A

CHAPTER: PHYSICAL AND CHEMICAL CHANGES

TOPICS TAUGHT: 

PHYSICAL CHANGE-LEARN DEFINE

PHYSICAL PROPERTIES 

CHARACTERISTICS OF PHYSICAL CHANGE

CRYSTALLIZATION--- ACTIVITY 1

https://www.youtube.com/watch?v=QdwKhbtzsug

HOMEWORK: REVISE THE TOPICS TAUGHT



DATE: 18/8/2021

GRADE: 7 A

CHAPTER: PHYSICAL AND CHEMICAL CHANGES

TOPICS TAUGHT: 

CHEMICAL CHANGE-LEARN DEFINE

CHEMICAL PROPERTIES 

CHARACTERISTICS OF CHEMICAL CHANGE

ACIDS, BASES, SALTS, LITMUS PAPER

CHEMICAL REACTIONS

https://www.youtube.com/watch?v=QdwKhbtzsug

HOMEWORK: REVISE THE TOPICS TAUGHT

Acids and Bases Definition

An acid is any hydrogen-containing substance that is capable of donating a proton (hydrogen ion) to another substance.  A base is a molecule or ion able to accept a hydrogen ion from an acid.

Acidic substances are usually identified by their sour taste. An acid is basically a molecule which can donate an H+ ion and can remain energetically favourable after a loss of H+. Acids are known to turn blue litmus red.

Bases, on the other hand, are characterized by a bitter taste and a slippery texture. A base that can be dissolved in water is referred to as an alkali. When these substances chemically react with acids, they yield salts. Bases are known to turn red litmus blue.


Properties of Acids and Bases

1. Properties of Acids

  • Acids are corrosive in nature.
  • They are good conductors of electricity.
  • Their pH values are always less than 7.
  • When reacted with metals, these substances produce hydrogen gas.
  • Acids are sour-tasting substances.
  • Examples: Sulfuric acid [H2SO4], Hydrochloric acid [HCl], Acetic acid [CH3COOH].

2. Properties of Bases

Some properties, like a bitter taste, are owned by all bases. The bases feel slippery, too. Dream on what slippery soap looks like. And this is a foundation. Furthermore, when immersed in water, bases conduct electricity because they consist of charged particles in the solution.

  • They are found to have a soapy texture when touched.
  • These substances release hydroxide ions (OH– ions) when dissolved in water.
  • In their aqueous solutions, bases act as good conductors of electricity.
  • The pH values corresponding to bases are always greater than 7.
  • Bases are bitter-tasting substances which have the ability to turn red litmus paper blue.
  • Examples: Sodium hydroxide [NaOH], milk of magnesia [Mg(OH)2], calcium hydroxide [Ca(OH)2].

3. Neutral Substances

The neutral substance is a substance which has no acid or base properties, has the same amount of hydrogen and hydroxyl ions, and does not modify the colour of the litmus surface.

  • These substances do not display any acidic or basic characteristics.
  • Their pH values approximate to 7.
  • Neutral substances have no effect on red or blue litmus paper.
  • The pH of pure water is exactly 7.
  • Examples: Water, Common salt (NaCl)

Difference between Acids and Bases

AcidsBases
Acid gives off hydrogen ions when dissolved in water.Bases give off hydroxyl ion when dissolved in water.
It turns blue colour litmus paper into red.It turns red colour litmus paper into blue.
It has a sour taste.It has bitter taste and soapy to touch.
Its pH value ranges from 1 to 7.Its pH value ranges from 7 to 14.
Example: HCl, H2SO4 etc.Example: NaOH, KOH etc.




Uses of Acids and Bases

The various uses of acids and bases are listed in this subsection.

1. Uses of Acids

  • Vinegar, a diluted solution of acetic acid, has various household applications. It is primarily used as a food preservative.
  • Citric acid is an integral part of lemon juice and orange juice. It can also be used in the preservation of food.
  • Sulfuric acid is widely used in batteries. The batteries used to start the engines of automobiles commonly contain this acid.
  • The industrial production of explosives, dyes, paints, and fertilizers involves the use of sulfuric acid and nitric acid.
  • Phosphoric acid is a key ingredient in many soft drinks.

2. Uses of Bases

  • The manufacturing of soap and paper involves the use of sodium hydroxide. NaOH is also used in the manufacture of rayon.
  • Ca(OH)2, also known as slaked lime or calcium hydroxide, is used to manufacture bleaching powder.
  • Dry mixes used in painting or decoration are made with the help of calcium hydroxide.
  • Magnesium hydroxide, also known as milk of magnesia, is commonly used as a laxative. It also reduces any excess acidity in the human stomach and is, therefore, used as an antacid.
  • Ammonium hydroxide is a very important reagent used in laboratories.
  • Any excess acidity in soils can be neutralized by employing slaked lime.




DATE: 23/8/2021

GRADE: 7 A

CHAPTER: ACIDS, BASES AND SALTS

TOPICS TAUGHT: 

ACIDS, BASES -TYPES,PROPERTIES, USES

INDICATORS



HOMEWORK: REVISE THE TOPICS TAUGHT

MULTIPLE ASSESSMENT(5 MARKS) MANDATORY

TO BE SUBMITTED TILL 10/9/2021

To create a concept map representing Acids, bases and salts.

CHOOSE ANY ONE TOPIC FROM BELOW-

→ Acids (properties, types, examples) 

→ Bases (properties, types, examples)

 → Indicators (use, types, examples) 

→ Neutralisation (reaction, applications in everyday life)

MATERIALS REQUIRED- a chart paper, sketch pens, glue, pictures relevant to the topics and subtopics (optional)

 To read the Chapter 5: Acids, Bases and salts. 

•  To prepare a concept map for the chapter.

 Can use- a hierarchical system or spider type approaches based on your creativity of how to best display the connection between the topics and subtopics.) 

• Can stick pictures or draw pictures relevant to the topics and subtopics and paste them in the concept map. 

 •  To create a concept map using lines or arrows to connect topics and sub topics.

 •  → limit the amount of information while making the map as much as possible → use bigger fonts such that the contents of the chart are visible, if placed on any wall of the class room later → use/paste pictures wherever required 

• Once the concept map is completed, CAN MAKE A VIDEO EXPLAINING IT AND WILL BE SHARED IN THE CLASS ( to share and reflect on how they each made the connections between concepts)




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