- Trending Categories
Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
A sulphate salt of Group 2 element of the Periodic Table is a white, soft substance, which can be moulded into different shapes by making its dough. When this compound is left in the open for some time, it becomes a solid mass and cannot be used for moulding purposes. Identify the sulphate salt, and why does it show such behaviour? Give the reaction involved.
Calcium belongs to group 2. Calcium sulphate is a white soft substance. It is known as Plaster of Paris, which can be moulded into different shapes by making its dough.
When Plaster of Paris is left for some time in open, it turns into a solid mass because of a reaction with moisture present in the atmosphere. The solid mass so formed is known as gypsum and cannot be further used for moulding.
The chemical equation is given below:
$CaSO_4.1/2H_2O+ H_2O + 1/2H_2O→CaSO_4.2H_2O$
Plaster of Paris Gypsum
- Related Articles
- An element A is soft and can be cut with a knife. This is very reactive to air and cannot be kept open in the air. It reacts vigorously with water. Identify the element from the followingMgNaPCa
- When some wheat dough was left in the open for a few days, it started emitting foul smell. Why?
- Identify the acid and base for ammonium chloride salt. What would be the nature of this salt? Mention the pH range of this salt.
- (a) As element X has mass number 40 and contains 21 neutrons in its atom. To which group of the periodic table does it belong?(b) The element X forms a compound X2Y. Suggest an element that Y might be and give reasons for your choice.
- Identify the acid and the base from which sodium chloride is obtained. Which type of salt is it? When is it called rock salt? How is rock salt formed?
- An element is soft and can be cut easily with a knife. It is very reactive and cannot be kept open in the air. It reacts vigorously with water. This element is most likely to be:magnesiumpotassiumphosphorousaluminium
- Salt can be separated from its solution (salt dissolved in water), because(a) mixing of salt in water is a change that can be reversed by heating and melting of salt(b) mixing of salt in water is a change that cannot be reversed(c) mixing of salt in water is a permanent ‘ change(d) mixing of salt in water is a change that can be reversed by evaporation.
- A student requires hard water for an experiment in his laboratory which is not available in the neighbouring area. In the laboratory, there are some salts, which when dissolved in distilled water can convert it into hard water. Select from the following groups of salts, a group, each salt of which when dissolved in distilled water will make it hard.(A) Sodium chloride, Potassium chloride(B) Sodium sulphate, Potassium sulphate(C) Sodium sulphate, Calcium sulphate(D) Calcium sulphate, Calcium chloride
- A compound ‘A’ is used in the manufacture of cement. When dissolved in water, it evolves a large amount of heat and forms compound ‘B’.(i) Identify A and B.(ii) Write chemical equation for the reaction of A with water.(iii) List two types of reaction in which this reaction may be classified.
- The pH of a salt used to make tasty and crispy pakoras is 14. Identify the salt and write a chemical equation for its formation. List its two uses.
- The metal salt A is blue in colour. When salt A is heated strongly over a burner, then a substance B is eliminated and a white powder C is left behind. When a few drops of a liquid D are added to powder C, it becomes blue again. What could be A, B, C and D?
- Give reasons for the following:(a) Sodium and potassium are stored in kerosene.(b) Copper cannot displace zinc from its salt solution (zinc sulphate solution).
- A metal salt MX when exposed to light splits up to form metal M and a gas X2. Metal M is used in making ornaments whereas gas X2 is used in making bleaching powder. The salt MX is itself used in black and white photography.(a) What do you think metal M is?(b) What could be gas X2?(c) Name the metal salt MX.(d) Name any two salt solutions which on mixing together can produce a precipitate of salt MX.(e) What type of chemical reaction takes place when salt MX is exposed to light? Write the equation of the reaction.
- Salt A commonly used in bakery products on heating gets converted into another salt B which itself is used for removal of hardness of water, and a gas C is evolved. The gas C, when passed through lime water, turns it milky. Identify A, B and C.
- A white powdery substance having strong smell of chlorine is used for disinfecting drinking water supply at waterworks. Identify the substance. Give its chemical name and write the chemical reaction preparation.
Advertisements