Sample Questions Strong and Weak Bases

Q1: Explain why a sodium sulphate aqueous solution is neutral and a sodium carbonate aqueous solution is basic in nature.

Answer:

Aqueous sodium sulphate solution is hydrolyzed to create sodium hydroxide and sulphuric acid, both of which are strong bases and acids. As a result, the aqueous solution is pH neutral. When sodium carbonate is dissolved in water, it is partially hydrolyzed, yielding sodium hydroxide and carbonic acid. 

Sodium hydroxide is now a strong base that is fully ionised and produces a significant number of hydroxide ions [OH^– (aq)]. Carbonic acid, on the other hand, is a weak acid that is only minimally ionised and hence produces a modest number of hydrogen ions [H⁺ (aq)]. The combination is basic because it includes more hydroxide ions than hydrogen ions.

Q2: Is sodium hydroxide a base that isn’t very strong? Is there any reason to believe that?

Answer:

A strong base is sodium hydroxide, a chemical substance having the formula NaOH. This is due to the fact that when sodium hydroxide is dissolved in water, it almost completely ionises. The basic chemicals that do not totally ionise in water are known as weak bases. An example of a weak base is ammonia. When NH₃ is dissolved in water, it interacts with the water molecules and dissociates into ammonium cation and hydroxide anions. However, some ammonia in the solution stays unionised.

Q3: Why do acids like HCl, HNO₃, and others have acidic properties in aqueous solutions, but molecules like alcohol and glucose don’t?

Answer:

In aqueous solutions, ionised solutions such as HCl, HNO3, and others become acidic due to the presence of H+ ions. Because alcohol and glucose solutions do not generate any of these ions, they do not have acidic properties.

Q4: Why not keep curd and sour substances in brass and copper vessels?

Answer:

Acids in curd and sour things react with copper vessels and brass to generate hazardous chemicals.

Q5: Why does the colour of dry litmus paper not change when exposed to dry HCl gas?

Answer:

The acidic quality of dry HCl gas is not transmitted since it does not release H⁺ ions.

The citric acid in fruits like oranges and lemons, tartaric acid in tamarind, malic acid in apples, lactic acid in milk and milk products, and hydrochloric acid in gastric juices are just a few examples of acids and bases found in nature. Many bases, such as lime water, can also be found. Many of these acids are used in our daily lives, such as vinegar or acetic acid in the kitchen, boric acid in laundry, baking soda in cooking, washing soda in cleaning, and so on.

Many acids and bases that we do not use in our daily lives are utilised in laboratories and industries, such as HCl, H₂SO₄, and NaOH, KOH, among others. The neutralisation process results in the creation of salt and water when these acids and bases are mixed in the proper quantities.