To show that the reaction between HCl and NaOH is a neutralization reaction.
A neutralization reaction is a chemical reaction that occurs when an acid and a base react quantitatively to produce salt and water as products.
When an acid and a base react to produce water and salt by combining H+ and OH- ions, a neutralization reaction occurs. The pH of a strong acid and a strong base, when neutralized, is 7. When a strong acid and weak base are neutralized, the resultant pH is less than 7, and when a strong base neutralises a weak acid, the resulting pH is more than 7.
When you touch the tube right after it has been neutralized, it feels hot. In a neutralization, reaction heat is always produced. When an acid reacts with a base, a new substance is produced. This new substance is called salt. Salt may be acidic, basic, or neutral.
Consider the reaction between HCl and NaOH in aqueous medium
HCl(aq)acid+NaOH(aq)base⇋NaCl(aq)salt+H2O(l)water
The liquid phenolphthalein is colourless. When added to a basic solution, its colour changes to pink. There is no colour change with acids.
Depending on the amounts of acidic and basic solutions combined, the final solution can be acidic, basic, or neutral. When an acid solution and a base solution are combined in the proper proportions, both the base's basic and acidic properties are neutralized or eliminated. The finished product is neither acidic nor basic. It is neutral. To understand the changes, we us Indicators and it is defined as when it is in contact with acids and bases, an indicator is a type of "dye" that changes colour. If the colour of the substance changes, this indicates whether the substance is an acid or a base.
The three most popular indicators for testing acids and bases are phenolphthalein, methyl orange, and litmus.
| Indicator | Colour in acid(pH < 7) | Colour at pH = 7 | Colour in base(pH > 7) |
| Red cabbage water | Red, pink | Purple | Blue,green,yellow |
| Turmeric water | Yellow | Yellow | Red |
| Phenolphthalein | Colourless | Colourless | Pink,red |
| Universal indicator | Red, orange, yellow | Green | Blue, violet, purple |
Farmers use lime to neutralise acidic soils (calcium oxide). Hydrochloric acid is found in the gut, and too much of it causes indigestion. Antacid tablets contain bases such as magnesium hydroxide and carbonate to neutralise excess acid. To neutralise excess acid antacid tablets, contain bases such as magnesium hydroxide and magnesium carbonate.
Vinegar is used to treat wasp stings that are alkaline in nature. Baking powder is used to treat bee stings and ant bites that are acidic in nature. Toothpaste contains bases that neutralise the acid produced by bacteria in our mouth. Baking powder is commonly used to make cakes grow.
Students will be able to
