This PSEB 7th Class Science Notes Chapter 5 Acids, Bases and Salts will help you in revision during exams.
PSEB 7th Class Science Notes Chapter 5 Acids, Bases and Salts
→ We eat many foods with different tastes in our daily life.
→ Some foods taste bitter, sour, sweet, and salty.
→ The sour taste of the substance is due to the acid present in them.
→ The word acid is derived from the Latin word ‘acere’, which means sour.
→ Substances that have a bitter taste and are soapy to touch, are called the base.
→ Indicators are substances that give different colours to substances or solutions of acidic and basic nature.
→ They are used to test the acidic or alkaline nature of substances.
→ Turmeric, litmus, and China rose petals (Gudhal) are natural indicators.
→ Neutral solutions do not change the color of litmus red or blue because they are neither acidic nor basic.
→ Phenolphthalein is a synthetic indicator that is prepared in the laboratory.
→ Some acids are strong and some are weak.
→ The reaction between an acid and a base is called Neutralisation.
→ Antacids are used to treat indigestion.
→ Solution of baking soda (Sodium hydrogen carbonate) rubbed to treat the effects of insect bites.
→ The basicity of the soil is eliminated by the use of organic matter.
→ The acidity of the soil is treated with bases like a quick (calcium oxide) or slaked lime (Calcium hydroxide).
→ Waste products from factories should be released into the water only after treatment with basic substances.
→ Acids: Substances that have a sour taste and which react with blue litmus solution to make its color red are called acids.
→ Bases (Alkali): Substances that have a bitter taste and which react with red litmus solution to make it blue are called bases.
→ Neutralisation: The reaction between an acid and an alkali is called neutralisation.
→ Neutral solution: A solution that is neither acidic in nature nor alkaline in nature is called a neutral solution or solution which does not change the color of the indicator is called a neutral solution.
→ Indicators: Indicators are substances that show different colours by reacting with different acids, salts, and bases.