Acids
Acids are chemicals that react with bases to generate salts and water, taste sour, and turn blue litmus paper red. The Latin word “acidus,” which means sour.
Characteristics of Acids:
1.Taste: The taste of acids is sour. Citrus fruits, such as oranges and lemons, contain citric acid, whereas vinegar contains acetic acid.
2. pH Value: The pH of acids is lower than 7. The degree to which an acid’s pH deviates from 7 indicates how strong it is.
3. Reaction with Metals: Hydrogen gas is created when acids react with metals such as magnesium and zinc. For example:
Zn + 2HCl → ZnCl2 + H2↑
4. Electrical Conductivity: Because of the free ions they contain, acids in aqueous solutions transmit electricity.
5. Corrosiveness: Strong acids like sulfuric acid (H2SO4) are highly corrosive.
Types of Acids:
1.Based on Origin:
Organic Acids: Found in plants and animals (e.g., acetic acid in vinegar, citric acid in citrus fruits).
Inorganic Acids: Found in minerals (e.g., hydrochloric acid (HCl), nitric acid (H N O3).
2. Based on Strength:
Strong Acids: Completely dissociate in water (e.g.,
HCl, H2SO4).Weak Acids: Partially dissociate in water (e.g., acetic acid (C H3 COOH).
Bases
Bases are compounds that turn red litmus paper blue, have a bitter taste, and feel polished. They create salts and water by neutralising acids.
Characteristics of Bases:
1.Taste: Bases have a bitter taste, like baking soda.
2. pH Value: Bases have a pH greater than 7.
3. Reaction with Acids: Bases react with acids to form salts and water in a neutralisation reaction. NaOH + HCl → NaCl + H2O
4. Electrical Conductivity: Aqueous solutions of bases conduct electricity due to the presence of hydroxide ions (OH−).
Types of Bases:
1.Strong Bases: Fully ionize in water (e.g., sodium hydroxide (NaOH), potassium hydroxide (KOH).
2. Weak Bases: Partially ionize in water (e.g., ammonium hydroxide (N H4 OH).
Uses of Bases:
Sodium hydroxide is used in soap making.
Calcium hydroxide (slaked lime) is used in cement and to neutralise acidic soils.
Ammonium hydroxide is used in household cleaners.
Salts
Ionic molecules called salts are created when an acid and a base neutralise one another. They are made up of negatively charged ions from the acid (anions) and positively charged ions (cations) from the base.
Characteristics of Salts:
1.Taste: Salts usually have a characteristic taste. Common salt (NaCl) is salty.
2. Solubility: Many salts are soluble in water, though some, like barium sulfate (BaSO4), are not.
3. pH Nature: Salts can be neutral, acidic, or basic depending on their parent acid and base.
Types of Salts:
1.Neutral Salts: Formed from a strong acid and a strong base (e.g., NaCl).
2. Acidic Salts: Formed from a strong acid and a weak base (e.g., ammonium chloride (N H4 Cl).
3. Basic Salts: Formed from a weak acid and a strong base (e.g., sodium carbonate (Na2CO3).
Uses of Salts:
Sodium chloride (NaCl) is used in cooking and food preservation.
Calcium carbonate (CaCO3) is used in the manufacture of cement and lime.
Potassium nitrate (K N O3) is used in fertilizers and fireworks.
Neutralisation Reaction
Neutralisation is the process by which an acid and a base combine to form salt and water. In both biological and industrial processes, it is an essential response. For example:
HCl + NaOH → NaCl + H2O
Applications in Daily Life
1.Acids:
Citric acid in food preservation.
Sulfuric acid in vehicles batteries.
2. Bases:
Sodium bicarbonate in baking.
Ammonium hydroxide in cleaning solutions.
3. Salts:
Epsom salt (MgSO4) in therapeutic baths.
Common salt (NaCl) as is used in cooking and food preservation.
Key words to know :- pH (potential of Hydrogen)
A measure of how acidic or basic a substance or solution is. pH is measured on a scale of 0 to 14. On this scale, a pH value of 7 is neutral, which means it is neither acidic nor basic. A pH value of less than 7 means it is more acidic, and a pH value of more than 7 means it is more basic.
Note :-
Everything from the food to our daily consumable items even used in our businesses that available on planet are depend on acids, bases, and salts.
Their characteristics and responses not only broadens our knowledge but also enables us to efficiently utilise their potential. These materials serve as daily reminders for us to have gifts from God, whether it’s the washing properties of soap or the sour trace of a lemon.
In aqueous solutions, acids are compounds that produce hydrogen ions (H+). They turn blue litmus paper red and have a sour taste. Acids are categorised according to:
Origin:
Organic acids: Found in plants and animals (e.g., citric acid, acetic acid).
Inorganic acids: Found in minerals (e.g., hydrochloric acid, sulfuric acid).
Strength:
Strong acids: Fully dissociate in water (e.g., HCl, H2SO4).
Weak acids: Partially dissociate in water (e.g., CH3COOH).
Bases are substances that release hydroxide ions (OH−) in aqueous solutions. Key characteristics are:
Bitter taste and slippery texture.
Turning red litmus paper blue.
Reacting with acids to form salts and water (neutralisation reaction).
Having a pH greater than 7.
The pH scale measures the acidity or basicity of a substance:
Acids: pH less than 7 (e.g., lemon juice has a pH of about 2).
Neutral substances: pH of 7 (e.g., pure water).
Bases: pH greater than 7 (e.g., sodium hydroxide has a pH around 13).
Salts are ionic compounds formed from the neutralization reaction between an acid and a base. For example:
HCl + NaOH → NaCl + H2O
Here, sodium chloride (NaCl) is the salt formed. Salts consist of the cation from the base and the anion from the acid.
Acidic salts: Ammonium chloride (N H4 Cl) – formed from a strong acid and a weak base.
Basic salts: Sodium carbonate (Na2CO3) – formed from a weak acid and a strong base.
Neutral salts: Sodium chloride (NaCl) – formed from a strong acid and a strong base.
Acids:
Citric acid in food preservation.
Sulfuric acid in car batteries.
Bases:
Sodium hydroxide in soap making.
Ammonium hydroxide in household cleaners.
Salts:
Sodium chloride (NaCl) as table salt.
Calcium carbonate (CaCO3) in cement production.