Topic 1b- Water Flashcards
Briefly describe the structure of a water molecule.
A water molecule consists of one oxygen atom bonded to two different hydrogen atoms. The molecule is bent in shape, with the oxygen atom attracting the shared electrons more strongly due to its higher electronegativity.
Why is water’s high specific heat capacity useful for living organisms?
Because many organisms are mainly composed of water, the property of high heat capacity allows highly regulated internal body temperatures.
Describe how a positive ion dissolves in water.
When a positive ion dissolves in water, the ions are attracted to the water molecules, which carry a polar charge. If the force between the ions and the water molecules is strong enough to break the bonds between the ions, the compound dissolves.
In hot temperatures, elephants commonly spray themselves with water. With reference to the structure and properties of water, explain:
a) Why this behaviour acts as a cooling mechanism for the elephant.
b) Why water forms droplets when the elephant sprays it from it’s trunk.
a) As the water evaporates from the surface of the elephant’s body, some of the elephant’s heat energy is used to break the hydrogen bonds which hold the water molecules together. This cools the surface of the elephant’s body.
b) There is strong cohesion between water molecules. This results in water having a high surface tension when in contact with air, causing it to form droplets.
