3.2 Water Flashcards
Define the term polar molecule. (2 marks)
Molecules which have regions of negativity and regions of positivity.
Explain why water is polar. (4 marks)
The oxygen is slightly negative compared with the hydrogens which are slightly positive. This is due to the uneven distribution of electrons, the oxygen has a greater pull on them because it has more electrons.
How do water molecules interact? (1 mark)
Hydrogen bonds
What gives water it’s unique characteristics? (1 mark)
Hydrogen bonding between molecules.
Why does water have an unusually high specific heat capacity? (3 marks)
There are many hydrogen bonds between molecules, difficult to overcome. Therefore it takes a lot of energy to increase the temperature of water.
Why does ice float? (3 marks)
Because, in ice, the hydrogen bonds are fixed in positions where the polar molecules are slightly further apart than in water. This produces a rigid but open structure. Making ice less dense than water.
Why does water have cohesive qualities? (1 mark)
The molecules are attracted to each other, so it moves as one mass.
What do the cohesive qualities of water allow plants to do? (1 mark)
Draw water up their roots .
Water has adhered ice qualities, what does this mean? (1 mark)
The molecules are attracted to other molecules.
Hint: think sticky tape
Water molecules are more strongly cohesive to each other than the air, what does this cause? (1 mark)
Surface tension
Water is a solvent, how does this help sustain life? (3 marks)
Many solutes in an organism can be dissolved in it.
Water acts as a medium for chemical reactions.
It helps transport dissolved substances in and out of cells.
How can water’s high specific heat capacity he’ll sustain life? (3 marks)
It acts as a temperature buffer, maintaining constant temperatures in cellular environments (enzymes are affected by temperature) and for organisms that live in water.
How can ice being able to float help sustain life? (2 marks)
In winter, it forms an insulating layer on top of water, allowing aquatic organisms to survive freezing temperatures.
