Grade 6 ↓
Acids, Bases and Salts
Chemistry is all around us. It's in the air we breathe, the food we eat, and even the cleaning supplies we use around the house. An essential part of chemistry involves acids, bases, and salts. In this lesson, we're going to explore these fascinating substances, which play a big role in chemistry and our daily lives.
What are acids?
Acids are chemicals that taste sour. Did you know that the lemon juice you drink in your lemonade is acidic? It contains citric acid. Other common acids include vinegar, which contains acetic acid, and hydrochloric acid which is found in our stomach and helps us digest food.
Common acids and their chemical formulas:
- Citric acid: C₆H₈O₇
- Acetic acid: CH₃COOH
- Hydrochloric acid: HCl
Properties of acids
- Acids generally taste sour.
- They can turn blue litmus paper red.
- Acids can conduct electricity when dissolved in water.
- They can react with metals to produce hydrogen gas.
- Acids can neutralise bases to form water and salt.
An important use of acids in everyday life is in the production of fertilizers, which help plants grow. For example, sulfuric acid is used to make phosphate fertilizers.
What are the bases?
Bases are chemicals that taste bitter and are slippery to the touch. They are often found in cleaning products because they can help break down grease and dirt. A common household base is sodium bicarbonate, also known as baking soda.
Common bases and their chemical formulas:
- Sodium bicarbonate: NaHCO₃
- Ammonia: NH₃
- Sodium hydroxide: NaOH
Properties of bases
- Bases have a bitter taste.
- They can turn red litmus paper blue.
- The base feels slippery or soapy to the touch.
- They can conduct electricity in solution.
- Bases can neutralise acids to form water and salt.
Baking soda or sodium bicarbonate is often used in cooking and cleaning. When used in cakes and cookies, it helps them rise by producing carbon dioxide gas when heated.
What are salts?
Salts are formed when acids and bases react with each other and are neutralized. The process of forming salts is called neutralization. Salts are found everywhere, from the table salt used on chips to Epsom salts dissolved in hot water.
Common salts and their chemical formulas:
- Table salt: NaCl (formed from hydrochloric acid and sodium hydroxide)
- Epsom salt: MgSO₄ (formed from magnesium and sulfuric acid)
Properties of salts
- Salts are usually solid and crystalline at room temperature.
- They can dissolve in water and form ions, allowing the solution to conduct electricity.
- Unlike acids and bases, salts do not change the colour of litmus paper.
An everyday example of salt is table salt, and its chemical name is sodium chloride (NaCl). It is used to make food taste good and to preserve it by preventing bacteria from growing.
Fail
The reaction between an acid and a base to form salt and water is called neutralization. This reaction is important because it can help balance or neutralize the pH level, which measures how acidic or alkaline a substance is.
Example of neutralization:
HCl + NaOH → NaCl + H₂O (Hydrochloric acid + Sodium hydroxide → Sodium chloride + Water)
Ph scale
The pH scale measures how acidic or alkaline a solution is. The scale runs from 0 to 14, with 7 being neutral. Substances with a pH less than 7 are acidic, while substances with a pH greater than 7 are alkaline.
For example, lemon juice has a pH of about 2, which is acidic, and household ammonia has a pH of about 11, which is alkaline. Pure water is neutral with a pH of 7.
Practical applications in everyday life
Acids, bases and salts have various uses in our daily life. Here are some examples:
- Acids: Used in food preservation (vinegar), cleaning products and car batteries (sulfuric acid).
- Alkali: Used in household cleaners, soap making, and baking (baking soda).
- Salts: Used as Epsom salts for cooking, water softening, and muscle relaxation.
Conclusion
Understanding acids, bases, and salts is very important in chemistry because they are part of countless reactions. These substances are important not only in laboratories and industries but also in our homes. By learning more about how they work and their properties, we can better understand the chemistry around us in our daily routine.