Define the terms solute, solvent and solution
Solute: Substances dissolved by the solvent (or the component present in a lower amount) •
Solvent: Substances in which solutes are dissolved (or the component present in a larger amount) •
Solution: A homogenous mixture of 2 or more substances
1.1.2. Identify the importance of water as a solvent.
Water is distributed in the biosphere, lithosphere, hydrosphere and atmosphere •
On earth, it is distributed as a solid, liquid and gas. Approximately 97% of water is in the oceans and 2% is locked up as ice in glaciers and polar icecaps. •
Water is essential as a reactant and a solvent in the recycling of C, O, N, P and S in nature. •
The importance of water as a solvent is it serves as a transport system for nutrients and waste products in living things •
It also allows biological processes to occur in aqueous solutions
1.1.3. Compare the state, percentage and distribution of water in the biosphere, lithosphere, hydrosphere and atmosphere. Location
Polar ice and glaciers
Rivers and streams
Salt water lakes
1.1.4. Outline the significance of the different states of water on Earth in terms of water as: -
A constituent of cells and its role as both a solvent and a raw material in metabolism. -
A habitat in which temperature extremes are less than nearby terrestrial habitats. -
An agent of weathering of rocks both as liquid and solid.
A natural resource for humans and other organisms.
Water is the predominant constituent of cells functioning as: -
A solvent for biochemical reactions that sustain life.
A raw material for metabolism (e.g. in plants).
A transport medium for nutrients and wastes.
A thermal buffer that resists large temperature fluctuations.
Water serves as a natural habitat for many organisms. A major disadvantage is that temperatures vary much less in water than on land. Marine organisms are therefore largely protected from experiencing temperature extremes.
Rock weathering and erosion
This is when water in rock crevices freezes and thaws repeatedly. The stress due to the expansion and contraction can cause rocks to fragment creating sediments over geological time. •
Rain, rivers and glaciers erode loose material, carving through mountains and shaping the landscape into its present form. •
Water can also chemically weather minerals present in rocks. Natural resource
Water is an essential component of everyday life. Humans use water for drinking, bathing, washing clothes, cleaning for industry and agriculture. 75% of water use in Australia is for irrigation of crops.
2.1.2. Compare the molecular structure of water, ammonia and hydrogen sulphide, the differences in their molecular shapes and in their melting and boiling points.
Melting & boiling point
Water Ammonia Hydrogen sulphide
2.1.3. Describe the hydrogen bonding between molecules.
Hydrogen bonds are a stronger form of the dipole-dipole force and only occur between partially positive hydrogen in one molecule and the lone pair of electrons of a fluorine, nitrogen or oxygen bonded to the hydrogen atoms in a neighbouring molecule. •
Hydrogen bonds are the strongest type of intermolecular forces.
2.1.4. Identify the water molecule as a polar molecule.
In water, there are 2 bonded electron pairs and 2 lone electron pairs •
There are dipole bonds between the oxygen and hydrogen atoms •
The oxygen atom is slightly...
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