CHEMISTRY Chapter Notes - Chapter full: Cobalt(Ii) Chloride, Copper(Ii) Sulfate, Heat Capacity
7 Mar 2023
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Course
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AIR AND WATER
IGCSE Requirements
GCE O Level Requirements
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WATER
General Information :
1. Water – chemical formula H2O, is a neutral, colourless liquid
2. At 1 atmospheric pressure, pure water boils at 1000C and freezes at 00C.
3. Water is the most known substance in this world. This is because of its abundance and
numerous uses.
4. Water is the commonest compound on this planet. More than 70% of the Earth’s surface
is covered with sea, and the land masses are dotted with rivers and lakes.
5. Water is vital to our existence and survival because it is one of the main
constituents in all living organisms.
a. For example, your bones contain 72% water, your kidneys are about 82% water
and your blood is about 90% water.
6. Water is, H2O, is the most widely used solvent for chemical reaction.
7. TEST FOR WATER
A. CHEMICAL TEST FOR THE PRESENCE OF WATER
1. ANHYDROUS COPPER(II) SULFATE
When we add water to white anhydrous copper(II) sulfate, it turns blue:
CuSO4(s) + 5H2O(l) CuSO4.5H2O(s)
2. ANHYDROUS COBALT (II) CHLORIDE PAPER.
When we add water to blue anhydrous cobalt(II) chloride, it turns red:
CoCl2(s) + 6H2O(l) CoCl2.6H2O(s)
BOTH COLOUR CHANGES CAN BE REVERSED BY HEATING.
BOTH OF THE ABOVE REACTIONS ARE REVERSIBLE.
B. TEST FOR PURITY OF WATER
If a liquid is pure water,
i. It will boil at 100 °C
ii. It will freeze at 0 °C
Document Summary
General information : water chemical formula h2o, is a neutral, colourless liquid, at 1 atmospheric pressure, pure water boils at 1000c and freezes at 00c, water is the most known substance in this world. This is because of its abundance and numerous uses: water is the commonest compound on this planet. When we add water to white anhydrous copper(ii) sulfate, it turns blue: Cuso4(s) + 5h2o(l) cuso4. 5h2o(s: anhydrous cobalt (ii) chloride paper. When we add water to blue anhydrous cobalt(ii) chloride, it turns red: Both colour changes can be reversed by heating. It will freeze at 0 c: the unique properties of water. It has an unusually high boiling point for a molecule of its relatively low molecular mass. It has a greater specific heat capacity than almost any other liquid. These unsual properties of water are due to a special type of.
