CIE Chemistry Paper-1: Specimen Questions 76 - 77 of 99
Question number: 76
What is the Chemical formula and chemical name of vinegar?
Nitric Acid - HNO₃
Lactic acid - CH₃CH (OH) COOH
Carbonic acid - H₂ CO₃
Acetic acid - CH₃COOH
Acetic acid has a chemical formula CH3COOH. Vinegar is roughly 3–9 % acetic acid by volume, making acetic acid the main component of vinegar apart from water. Vinegar is now mainly used as a cooking ingredient. Historically, as the most easily available mild acid, it had a great variety of industrial, medical and domestic uses, some of which (such as its use as a general household cleanser) are still promoted today.
Question number: 77
A solution of NaOH was taken in a test tube and phenolphthalein was added to it. The solution turned pink by doing so. Now HCl is added to it and the pink colour disappeared.
What reaction possibly would have taken place?
A neutralization reaction is when an acid and a base react to form water and a salt and involves the combination of H+ ions and OH- ions to generate water. The neutralization of a strong acid and strong base has a pH equal to 7.
This experiment shows that the addition of HCl destroys the alkaline nature of NaOH. On the other hand the addition of NaOH solution destroys the acidic nature of HCl. i. e. both NaOH and HCl appear to cancel the effect of each other.