1.7

Question 1

properties of water 7

Answer 1

● high specific heat capacity
● polar solvent
● surface tension
● incompressibility
● maximum density at 4 °C.
high latent heat of vaporisation
transparent

Question 2

bonding in water

Answer 2

• strong covalent bond
• unequal sharing of e-s
• O has delta neg and H has delta pos - dipolar nature means water molecules r attracted to each other

Question 3

the importance of the dipole nature of water leading to hydrogen
bonding

Answer 3

ITS BW WATER MOLECULES

Question 4

how does water have high specific heat capacity

Answer 4

• the fact that when water heated - temp increases as KE increases but in fact a lot of the heat energy added us used to break up H bonds bw h20 molecules so less energy available to increase temp so a lot of heat energy required to increase temp of water - high SHC

Question 5

the significance of the following to organisms:
● high specific heat capacity

Answer 5

• temp will be relatively thermally stable - so metabolism occurs at steady rate - enzymes less likely to denature/lower inactivity
• so stable environment for aquatic organisms

Question 6

the significance of the following to organisms:
● polar solvent

Answer 6

any polar substance dissolves in water easily so can be easily transported around animals/plants

Question 7

the significance of the following to organisms:
● surface tension

Answer 7

• surface of water - uppermost molecules only have molecules below - so they r pulled downwards by H bonds - this will draw them closer tg - forms strong layer on surface of water

Question 8

what is cohesion in terms of water molecules, how is it useful

Answer 8

H bonds pull water molecules in at surface as they attract each other = cohesion
- water moves up xylem in traps stream - H bonds help prevent breaking up molecule chain

Question 9

significance of the following to organisms:
● incompressibility

Answer 9

• close packing of molecules -> can resist force + transfer pressure -> support in aq organisms, supports opening of stomata

Question 10

significance of the following to organisms:
● maximum density at 4 °C.

Answer 10

• lower temps - water has less KE so H bonds pull water into rigid lattice structure which takes up bigger vol than liquid so lower density - this is why ice floats
• ice acts as insulator bc it floats to top and stops water below freezing so fish can still live + swim - cells + chemical reactions won’t freeze