7. All about water
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What type of bonding exists in water?
Covalent molecular
What is the molecular formula of water?
H 2 O
What shape is the water molecule?
Angular
What is meant by a polar molecule?
A molecule which has a separation of charge within it
Why is water a polar molecule?
What types of substances dissolve in water?
• ionic compounds • polar molecules
What is an electrostatic attraction?
An attraction between 2 opposite (+ve and -ve) charges,
What is the attraction between water molecules?
An electrostatic attraction between the as shown by dashed line in diagram
How do some water molecules get ionised?
The electrostatic attraction between molecules can cause one to break into 2 ions
Why does water conduct if it is covalent molecular substance?
Because some water molecules break into ions which are free to move in solution.
Why is pure water a poor conductor?
Beacuse the concenmtration of ions in solution is always very small Around 1 in 500 million are ionised at any one time
What are the 2 ions that water breaks into?
What is the alkaline ion?
Hydroxyl (OH- (aq) ) ion
What is the acid ion?
Hydrogen (H+ (aq) ) ion
Why does water have a pH of 7?
Because it ionises to produce equal numbers of H+ (aq) and OH- (aq) ions.
What is an “acidic oxide”
A NON-METAL oxide that is soluble in water
What is an “basic oxide”
A METAL oxide that is soluble in water
What is a pollutant?
A harmful substance released into the environment
What is acid rain?
Rain which falls with a pH of below 5.6
How do pollutants contribute to acid rain?
What are the 2 main pollutants that cause acid rain?
Sulphur dioxide Nitrogen oxides