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प्रश्न
Which of the following salt has a blue colour and why?
CuSO4.5H2O or CuSO4
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उत्तर
The CuSO4.5H2O has a blue colour. The blue colour is due to the presence of water molecules in the structure. The colour of a salt crystal is usually given by the water of crystallisation. But anhydrous salts (without the water molecules) lose their colour and shape and become white. Thus, CuSO4, which does not have water molecules, appears white.
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संबंधित प्रश्न
From the list of the following salts choose the salt that most appropriately fits the
description is given in the following:
[AgCl, MgCl2, NaHSO4, PbCO3, ZnCO3, KNO3, Ca(NO3)2]
On heating this salt, a brown colored gas is evolved.
Write a balanced equation for the preparation of the following salts:
Copper sulphate from copper carbonate.
What are the two main ways in which common salt (sodium chloride) occurs in nature?
Name the salt which is used as a preservative in pickles, and in curing meat and fish.
Common salt is obtained from sea-water by the process of ______.
Explain why chlorine is used for sterilising drinking water supply.
Name three products of the chlor-alkali process. State two uses of each of these products.
What is meant by ‘hydrated’ salts? Explain with examples.
Write the names, formulae and colours of any two hydrated salts.
The products of chloro-alkali process are ______.
A salt whose aqueous solution will have a pH of more than 7 will be ______.
Define the following term:
Hygroscopy
Outline the steps required to convert hydrogen chloride to anhydrous iron (III) chloride. Write the equations for the reactions.
Name two carbonates which do not produce carbon dioxide on heating.
Copy and complete the following table which refers to the action of heat on some carbonates:
| Carbonate | Colour of residue on cooling |
| Zinc Carbonate | |
| Lead carbonate | |
| Copper carbonate |
Salts A, B, C, D and E undergo reactions (i) to (v) respectively. Identify the anion present in these salts on the basis of these reactions.
- When silver nitrate solution is added to a solution of A, a white precipitate, insoluble in dilute nitric acid, is formed.
- The addition of dilute hydrochloric acid to B produces a gas which turns lead acetate black on paper.
- When a freshly prepared solution of ferrous sulphate is added to a solution of C and concentrated sulphuric acid is gently poured from the side of the test tube, a brown ring is formed.
- When dilute sulphuric acid is added to D, a gas is produced which turns acidified potassium dichromate solution from orange to green.
- The addition of dilute hydrochloric acid to E produces effervescence. The gas produced turns lime water milky but does not affect acidified potassium dichromate solution.
The Salt Story
From: The New Indian Express 9 March 2021
The salt pans in Marakkanam, a port town about 120 km from Chennai are the third largest producer of salt in Tamil Nadu. Separation of salt from water is a laborious process and the salt obtained is used as raw materials for manufacture of various sodium compounds.
One such compound is Sodium hydrogen carbonate, used in baking, as an antacid and in soda acid fire extinguishers.
The table shows the mass of various compounds obtained when 1litre of sea water is evaporated.
| COMPOUND | FORMULA | MASS OF SOLID PRESENT /g |
| Sodium Chloride | NaCl | 28.0 |
| Magnesium Chloride | MgCl2 | 8.0 |
| Magnesium Sulphate | MgSO4 | 6.0 |
| Calcium Sulphate | CaSO4 | 2.0 |
| Calcium Carbonate | CaCO3 | 1.0 |
| TOTAL AMOUNT OF SALT OBTAINED | 45.0 | |
What is the pH of the acid which is used in the formation of common salt?
One of the constituents of baking powder is sodium hydrogencarbonate. The other constituent is :
You are provided with the list of chemicals mentioned below in the box:
| Sodium hydroxide solution, copper carbonate, zinc, hydrochloric acid, copper, dilute sulphuric acid, chlorine, iron |
Using suitable chemicals from the list given, write a balanced chemical equation for the preparation of the salt mentioned below:
Sodium zincate
