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प्रश्न
What is meant by ‘hydrated’ salts? Explain with examples.
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उत्तर
The water molecules which form part of the structure of a crystal (of a salt) are called water of crystallisation. Salts that contain water of crystallisation are called hydrated salts.
Copper sulphate crystals contain 5 molecules of water of crystallisation in one formula unit and therefore are written as CuSO4.5H2O. It is called copper sulphate pentahydrate (Pentahydrate means five molecules of water).
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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 gives a yellow residue when hot and white when cold
Which of the following salt has a blue colour and why?
CuSO4.5H2O or CuSO4
Common salt is obtained from sea-water by the process of ______.
Complete and balance the following chemical equation:
\[\ce{NaCl + NH3 + H2O + CO2 ->}\]
What happens when a few drops of water are added to anhydrous copper sulphate? Explain with the help of an equation.
A salt is dissolved in water and the pH of this salt solution is measured with a universal indicator paper. If the pH of solution is less than 7, the salt is most likely to be ______.
Consider the following salts:
Na2CO3, NaCl, NH4Cl, CH3COONa, K2SO4, (NH)2SO4
Which of these salts will give:
- acidic solutions?
- neutral solutions?
- basic solutions (or alkaline solutions)?
What is a ‘salt’?
name two salts which are acidic.
Hard water required for an experiment is not available in a school laboratory. However, following salts are available in the laboratory. Select the salts which may be dissolved in water to make it hard for the experiment.
|
(1) |
Calcium Sulphate |
(2) |
Sodium Sulphate |
|
(3) |
Calcium Chloride |
(4) |
Potassium Sulphate |
|
(5) |
Sodium Hydrogen Carbonate |
(6) |
Magnesium Chloride |
(A) 1, 2 and 4
(B) 1, 3 and 6
(C) 3, 5 and 6
(D) 2, 4 and 5
State one observation for each of the following :
Lead nitric is heated strongly in a test tube.
Give four substances which contain water of crystallization and write their common name.
Taking sodium carbonate as an example, give the meaning of the following terms:
Anhydrous
Name gases which has a sour taste.
Distinguish by a chemical test sodium chloride and sodium sulphide.
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 | |
How many grams of Magnesium Sulphate are present in 135g of solid left by evaporation of sea water?
Salt which is formed by the partial replacement of hydrogen ions of an acid by a metal is called ______.
Name the salt formed when sulphuric acid is added to sodium hydroxide and write its pH.
