NIOS CLASS 10 SCIENCE 212 CHAPTER - 8 (ACIDS, BASES & SALTS) IMPORTANT NOTES FOR EXAM

NIOS CLASS 10 SCIENCE (212) IMPORTANT CHAPTER WISE NOTES FOR EXAM

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Important Terms to Remember: 

• Acids are the substances which taste sour, change blue litmus red, are corrosive to metals and furnish H⁺ ions in their aqueous solutions.
• Bases are the substances which taste bitter change red litmus blue, feel slippery and furnish OH^- ions in their aqueous solutions.
• Acids are presents in many unripe fruits, vinegar, lemon, sour milk etc., while bases are present in lime water, window pane cleaners, many drain cleaners etc.
• Aqueous solutions of acids and bases both conduct electricity as they dissociate on dissolving in water and liberate cations and anions which help in conducting electricity.
• Strong acids and bases dissociate completely in water.
• Weak acids and bases dissociate partially in water.
• Acids and bases react with each other to produce salt and water. Such reactions are called neutralization reactions.
• If pH of rain water falls below 5.6, it is called acid rain and is quite harmful.

Acids present in plant materials & animals are called Organic acids. Some naturally occurring acids,

Vinegar	Acetic acid
Sour milk (curd)	Lactic acid
Oranges	Citric acid
Lemons	Citric acid
Tamarind	Tartaric acid
Ant sting	Formic acid
Apples	Malic acid
Tomatoes	Oxalic acid.

Some common acids that are found in laboratories are

• Hydrochloric acid (HCl),
•  Sulphuric acid (H2SO4) and
•  Nitric acid (HNO3).

Some of the lesser used acids are

1. Acetic acid (CH3COOH),
2.  Hydrofluoric acid (HF), Hydrofluoric acid is a highly corrosive acid and is used to etch glass.
3.  Carbonic acid (H2CO3).

Characteristics / General properties of Acids:

1. Tastes sour
2.  Reacts with metals such as zinc, magnesium etc. liberating hydrogen gas.
3.  Changes the colour of litmus from blue to red.
4.  Conducts electricity.

Characteristics / General properties of Bases

1. Have a soapy feel,
2.  May also burn the skin
3.  Common examples are soaps & detergents.
4.  Commonly found bases in laboratories and in our daily life are: Caustic soda, NaOH; Caustic potash, KOH; Milk of magnesia, Mg(OH)2; Liquor ammonia, NH3; Washing powder, Tooth paste.

Chemical Properties of Acids

1. Turns blue litmus red
2.  Taste sour
3.  Acids corrodes metals
4.  Positively charged hydrogen ions(H+)
5.  Acids have pH values of less than 7

Chemical Properties of Bases

1. Turn red litmus blue
2.  Taste bitter
3.  Negatively charged hydroxide ions (OH-)
4.  Feel Slippery
5.  Most Hand Soaps and drain cleaners are bases
6.  Strong bases are caustic

Important Compounds

       1. Baking Soda (NaHCO₃)

               Raw Materials:

1. Lime Stone (CaCO₃)
2.  Concentrated NaCl Solution (brine)
3.  Ammonia (NH₃)

              Uses:

1. Cooking (Baking Powder)
2.  In medicine
3.  Fire Extinguisher

      2.  Washing Soda (Na₂CO₃.10H₂O)

              Uses:

1. Removing permanent hardness of water
2.  Domestic purpose (cleaning)
3.  Manufacture of NaOH, glass borax etc.

       3. Plaster of Paris

              Uses:

1. For making toys and statues
2.  Fire proof materials
3.  Chalk, in medicine
4.  Homes (design)

        4. Bleaching Powder (CaOCl₂)

             Uses:

1. Bleaching of cotton and linen
2. Manufacture CHCl₃
3.  Germicide
4.  Oxidising agent

            Also Read: NIOS CLASS 10 HINDI (201) CHAPTER - 17 IMPORTANT NOTES FOR EXAM

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