Question

State one relevant observation for each of the following reactions:
(i) Flame test is performed with calcium nitrate.
(ii) Water is added to anhydrous copper sulphate.
(iii) Copper carbonate is decomposed on heating.
(iv) Dil. ${H_2}S{O_4}$ is added to zinc sulphide.
(V) Addition of silver nitrate solution to sodium chloride solution.​

Answer 1

Hint : A chemical reaction occurs when one or more compounds, known as reactants, are changed into one or more distinct substances, known as products. Chemical elements or compounds are examples of substances. The component atoms of the reactants are rearranged in a chemical reaction, resulting in the formation of various substances as products.

Complete Step By Step Answer:
(i) Flame test is performed with calcium nitrate.
Calcium nitrate generates an orange-red flame when observed visually. The colour of flames is determined by the element's distinctive emission spectrum.
(ii) Water is added to anhydrous copper sulphate.
Anhydrous copper(II) sulphate and water react to form anhydrous copper(II) sulphate, which is used to test for water. In the presence of water, the white solid becomes blue.
$CuS{O_4} + 5{H_2}O \to CuS{O_4}.5{H_2}O$
(iii) Copper carbonate is decomposed on heating
When green copper carbonate is heated, copper oxide and carbon dioxide are formed. This is a reaction of decomposition. While heating, a rapid effervescence of carbon dioxide gas is emitted. When heat is given to a pure material, the particles reorganise into two or more new products, which is known as decomposition.
$CuC{O_3} \to CuO + C{O_2}$
(iv) Dil. ${H_2}S{O_4}$ is added to zinc sulphide.
Zinc is more reactive than hydrogen, and it binds to hydrogen in dilute acids. Zinc combines with dilute sulphuric acid to produce zinc sulphate, which emits hydrogen gas. This is a single non-metal displacement reaction by a metal.
$Zn + {H_2}S{O_4} \to ZnS{O_4} + {H_2}$
(V) Addition of silver nitrate solution to sodium chloride solution.​
During a chemical process, precipitation is the creation of a solid in a solution or within another solid. When the concentration of dissolved ions in a solution exceeds the solubility product, this process occurs.
$AgN{O_3} + NaCl \to NaN{O_3} + AgCl \downarrow$ .

Note :
Reactants or reagents are the chemicals (or substances) that are initially involved in a chemical reaction. Chemical reactions normally involve a chemical change and the formation of one or more products with characteristics distinct from the reactants. The information on the particular path of action is part of the reaction mechanism, which frequently consists of a succession of distinct sub-steps, referred to as elementary reactions. Chemical reactions are represented symbolically by chemical equations, which show the beginning ingredients, end products, and occasionally intermediate products, as well as the reaction circumstances.