Acids Bases and salts class 7 worksheets
Acids bases and salts. Download acids bases and salts class 7 worksheets based on the latest CBSE syllabus including fill in the blanks, short and long questions.
Acids, Bases and Salts (Points to remember)
Acids: A Substance that tastes sour.
Types of Acids: Mineral and organic acids, Concentrated and dilute acids
Properties of Acids: Acids have a sour taste
Acids turn blue litmus red.
All acidic solutions conduct electricity.
Alkalis: The bases that are soluble in water
Base: A substance that tastes bitter and feels slippery when touched.
Types of Bases: Strong and weak bases
Indicator: A substance that indicates whether the given solution is acidic or basic
Salts: The substance formed when an acid react with bases.
Neutralization: The reaction of an acid with a base to form a salt and water.
Curd, lemon juice, orange juice and vinegar taste sour. These substances taste sour because they contain acids. The chemical nature of such substances is acidic The word acid comes from the Latin word acere which means sour.
What about baking soda? Does it also taste sour? If not, what is its taste? Since, it does not taste sour it means, that it has no acids in it. It is bitter in taste. If you rub its solution between fingers, it feels soapy. Generally, substances like these which are bitter in taste and feel soapy on touching are known as bases.
Special type of substances are used to test whether a substance is acidic or basic. These substances are known as indicators. The indicators change their colour when added to a solution containing an acidic or a basic Turmeric, litmus, China rose petals (Gudhal), etc., are some of the naturally occurring indicators.
In neutralisation reaction a new substance is formed. This is called salt. Salt may be acidic, basic or neutral in nature.
When an ant bites, it injects the acidic liquid (formic acid) into the skin. The effect of the acid can be neutralised by rubbing moist baking soda (sodium hydrogen carbonate) or calamine solution, which contains zinc carbonate.
Did you know?
The most commonly used natural indicator is litmus. It is extracted from lichens