Secondary Catalogue
Series: Acids, Bases, and Salts
Acids and Bases
Acids are sour in taste, while bases are bitter in taste and feel soapy. Acids and bases are present in a variety of things around us.
Caustic Soda
Sodium hydroxide is produced by the electrolysis of sodium chloride solution. During electrolysis, hydrogen gas gets evolved at the cathode and chlorine gas gets evolved at the anode.
Hydrated Salts
Hydrated salts are crystalline salts that contain water molecules within their structure. This water of crystallisation gives shape and colour to the crystal. On heating, hydrated salts lose their water of crystallisation and become anhydrous.
Natural Indicator: Turmeric and China Rose
A turmeric indicator changes the colour of a basic solution to red, and an acidic solution to pale yellow. A China rose indicator changes the colour of a basic solution to green, and an acidic solution to pink.
Neutralisation in Everyday Life
When an acid and a base react to form water and a salt, it is known as a neutralisation reaction. Neutralisation reactions have different applications - - in homes, in medicines, in agriculture and in Industries.
Reaction Between Acids and Bases
Acids react with bases to form the corresponding salt and water. For example, sodium hydroxide reacts with hydrochloric acid to form sodium chloride and water. Antacids, like milk of magnesia, provide relief from acidity and are basic in nature.
Reaction of Metal Oxides with Acids
Metal oxides react with acids to form their corresponding metal salts and water. Metal oxides and hydroxides are basic in nature and reactions of metal oxides and hydroxides with acids are considered similar to neutralisation reactions.
Strength of Acids
All acids have hydrogen, and, when dissolved in water, they produce hydronium ions. Strong acids completely ionise in an aqueous solution, while weak acids only partially ionise in an aqueous solution.
Strength of Bases
Most bases have hydroxide ions as their constituent element. Strong bases completely ionise in an aqueous solution while weak bases only partially ionise in an aqueous solution.
The Importance of pH in the Human Body
The pH in the human body tells about the value of the acidity or basicity of an aqueous solution. Acidity produced in the stomach, due to overeating, can be reduced by having an antacid, like the syrup milk of magnesia.
Uses of Bases
Many substances which are basic in nature are used in our daily lives. For example, toothpastes contain aluminium hydroxide, cleansing agents contain ammonium hydroxide, and antacid contains magnesium hydroxide.
What Acids Have in Common
All acids contain hydrogen. On reacting with metals, all acids produce hydrogen gas. All acids produce hydrogen ions in water. Compounds that contain hydrogen but do not generate hydrogen ions in aqueous medium are not acidic.