Chemistry Notes 24X7

A form of a chemical element in which the atoms have the same number of protons (part of the nucleus of an atom) but with a different number of neutrons.  For example : Carbon 12, Carbon 13, and Carbon 14 are isotopes of carbon.

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.  For example when HCl (Hydrochloric acid), a strong acid, reacts with NaOH, a strong base, the resulting salt is sodium chloride and water.

A homologous series is a group of organic compounds having similar structures and similar chemical properties in which the successive compounds differ by (CH2). Meaning of Homologous Series A homologous series refers to a series of carbon compounds which have a different number of carbon atoms. However, they contain the same functional group. In this series, a group of compounds share similar basic chemical makeup. Also, in such a series, the compounds show a difference in the number of iterations of a certain aspect of their structure. Properties of Homologous Series  Repeating unit is the most important characteristic of a homologous series. An example can be the alkaline group which consists of the CH2 repeating unit. What this means is that the compounds are identical with the notable exception of the number of CH2 units existing in the compound. Organic compounds certainly have functional groups. Moreover, these groups define the fundamental and basic properties of the compound. M

example of rancidity Some examples of rancidity are - Food when exposed to atmospheric air for a long duration becomes rancid. Butter changes its taste and smell when kept in an open atmosphere for a longer duration. Some precaution to prevent rancidity : Food should be kept in sealed containers. Food that needs to be refrigerated. Foods containing fat and oil can be packaged in nitrogen gas to prevent rancidity. To avoid rancidity, food should be stored away from light. Antioxidants can be added to food.

The oxidation of oils or fats in food resulting in a bad taste and smell is called rancidity.  OR It is a condition in which aerial oxidation of unsaturated fat present in food gives it an unpleasant flavour and odour. Rancidity makes food undesirable for consumption. This process is also called rancidification.

Answer :  Baking soda (NaHCO 3 ) liberates carbon dioxide gas on heating, confirmed by passing it in lime water. Whereas on heating washing soda Na 2 CO 3 .10H 2 O water of crystallisation is given out, the salt becomes anhydrous. Reaction: 2NaHCO 3  → Na 2 CO 3  + H 2 O + CO 2 Na 2 CO 3 .10H 2 O → Na 2 CO 3  + 10 H 2 O