- Taste and Touch: Bases have a bitter taste and feel soapy or slippery to the touch.
- Indicator Reaction: Bases turn red litmus blue, methyl orange yellow, and phenolphthalein pink.
- Soapy Reaction: Bases like caustic soda react with skin oils to form soap.
- Electrolytes: Strong bases are good conductors of electricity (strong electrolytes).
- Corrosive Nature: Bases can cause mild burns or skin irritation.
Definitions [8]
Definition: Acid
Acids are defined as compounds which contain one or more hydrogen atoms and when dissolved in water, produce hydronium ions (H3O+) the only positively charged ions.
Define Acid.
An acid is a compound which when dissolved in water produces hydronium ion(H3O+), the only positively charged
ion and a negative ion.
Define a base.
A base is defined as a chemical compound that, when it reacts with a hydronium ion or H+ ions furnished by an acid, forms a salt and water only.
Define the term ‘basicity’ of an acid.
The basicity of an acid is defined as the number of hydronium ions (H3O+) that can be produced by the ionization of one molecule of that acid in aqueous solution.
Define an acid.
Acids are substances that ionise on dissolving in water, producing hydrogen ions. Acids are those chemical substances which have a sour taste.
Definition: Alkali
An alkali is a basic hydroxide which when dissolved in water produces hydroxyl (OH-) ions as the only negatively charged ions.
Definition: Bases
A base is either a metallic oxide or a metallic hydroxide or ammonium hydroxide which reacts with hydronium ions of an acid to form a salt and water only.
Define neutralization.
Neutralization: A chemical reaction in which a base or an alkali reacts, with an acid to produce salt and water only.
\[\ce{\underset{\text{sodium hydroxide}}{NaOH(aq)} +\underset{\text{hydro chloride acid}}{HCl(aq)}->\underset{\text{sodium cholride}}{NaCl(aq)}+\underset{\text{water}}{H2O}}\]
Key Points
Key Points: Physical Properties of Acids
- Taste & Safety: Acids taste sour; mineral acids are corrosive and should never be tasted.
- Physical State: Acids can be solids (e.g., boric acid) or liquids (e.g., HCl, H₂SO₄); some are volatile, others are not.
- Skin Effect: Strong acids cause burns; conc. H₂SO₄ chars skin, HNO₃ turns it yellow, HCl gives amber color.
- Indicators: Acids turn blue litmus red; also change colors of methyl orange and red cabbage extract.
- Conductivity: Acids conduct electricity in aqueous solutions, acting as electrolytes.
Key Points: Physical Properties of Bases
