Water of Crystallisation

1. By,
V.S.Rashmi Priyem
8th A
1983
VMJ SCHOOL

2. Let us know
 Water molecules bonded to the
molecule of a substance are
called water of crystallisation.
 Such a substance is called hydrated
substance

3. Hydrated Salt in Sea

4. Effect of heating some hydrated
salts
Different hydrated salts show
different behaviour on heating.

5. Chemical Name Common Name Formula
Copper Sulphate Blue vitriol CuSO4. 5H2O
Magnesium Sulphate Epsom Salt MgSO4.7H2O
Sodium Carbonate Washing Soda NaCO3.10H2O
Ferrous Sulphate Green Vitriol FeSO4.7H2O
Magnesium Chloride Magnesium
Chloride
MgCl2.6H2O
Sodium Borate Borax Na2B4O7.10H2O
Sodium Sulphate Glauber’s Salt Na2SO4.10H2O

6. Blue vitriol, copper
sulphate
 Copper sulphate comes in a hydrated
form copper sulphate pentahydrate and
a anhydrous form

7. Epsom salt, Magnesium sulphate
 Magnesium sulphate is an inorganic salt
(chemical compound) containing
magnesium, sulphur and oxygen.
 With the formula MgSO4.
 It is often encountered as the
heptahydrate sulfate mineral epsomite
(MgSO4·7H2O), commonly called
Epsom salt.

8. Washing Soda, Sodium
Carbonate
 Also known as washing soda,
soda ash and soda crystals
 Na2CO3, is a sodium salt of
carbonic acid
 It most commonly occurs as a
crystalline heptahydrate,
which readily efflorescence to
form a white powder, the
monohydrate.

9. Green vitriol, Hydrated Ferrous
sulphate
 A white powder of anhydrous
FeSO4 is first obtained on
heating, accompanied by
evolution of steam.
 On further heating, a brown
residue of Fe2O3 is obtained
along with the evolution of a
mixture of sulphur dioxide and
sulphur trioxide gases.

10. Magnesium chloride
 It melts on heating. it gives off not only
steam, but also magnesium oxide and
hydrochloric acid gas
 MgCl2.6H2O

11. Borax, Hydrated Sodium
borate
 It melts on heating then swells up, giving
large amounts of steam. On cooling, the
molten mass solidifies to form a
transparent solid.

12. Glauber’s Salt, Sodium
Sulphate
 Sodium sulfate is the sodium salt of
sulphuric acid.
 When anhydrous, it is a white
crystalline solid of formula Na2SO4
known as the mineral thenardite
 The decahydrate Na2SO4·10H2O is
found naturally as the mineral
mirabilite, and in processed form has
been known as Glauber's salt or,
historically, sal mirabilis since the
17th century.
 Another solid is the heptahydrate,
which transforms to mirabilite when
cooled.

13. Anhydrous salts
 Not all the salts contain water of
crystallisation
 For example, salts like Sodium chloride,
Potassium nitrate, Potassium
permanganate, Potassium dichromate,
Ammonium chloride,etc.,are not
associated with any water molecules of
crystallisation
 Such substances are called anhydrous salts

14. Efflorescence
 Certain hydrated substance have a
tendency to lose water of crystallisation.
 Such substances are called efflorescent

15. Efflorescence
 The hydrated substance forms a white
powder.
 It is believed that the hydrated
substance partially loses water of
crystallisation

16. Efflorescence
 Sodium carbonate on exposure to air
loses water of crystallisation and forms
Na2CO3.H2O which is an amorphous
substance

17. Examples of efflorescent
substances
Substance Formula
Epsom salt MgSO4.7H2O
Glauber’s salt Na2SO4.10H2O
Washing soda Na2CO3.10H2O
Green vitriol FeSO4.7H2O
Blue vitriol CuSO4.5H2O

18. Deliquescence
 Certain substances, on exposure to
atmosphere, absorb moisture to such an
extent that they change into liquid state
 Such substances are called deliquescent
substances
 This phenomenon is known as
deliquescence

19. Examples of deliquescent
substances
Potassium hydroxide(KOH)
Sodium hydroxide(NaOH)
Phosphorus pentoxide(P2O5)
Ferric chloride(FeCl3)
Mercuric nitrate(Hg(NO3)2)

20. Hygroscopic substances
 Certain other substances absorb
moisture from the air ,but do not
change their physical state, they
remain the same.
 Such substances are called hygroscopic
substances

21. Examples of hygroscopic
substances
 Quick lime(CaO)
 Concentrated sulphuric acid(H2SO4)
 Anhydrous copper sulphate(CuSO4)

22. Day to Day Application of
Water Crystallization
 Silica Water Absorber
 In Capsule Box, Shoe Box, Electronic
Device Containers
 Transformer
 Silica Gel Breather in minimize Moisture
entry into Transformer
 To measure Humidity

23. Video on hydrated
salts