1. Importance and Distribution

1. Importance and Distribution

1. 4.1.1.2 - Identify the importance of water as a solvent

   • Universal solvent
     • capable of dissolving a large range of substances
     • Biological process
       • through dissolution of substances
     • Transport medium
       • Carry substances like chemicals, nutrients, minerals and waste
     • Habitat

2. 4.1.1.3 - Compare the state, percentage and distribution of water in the biosphere, lithosphere, hydrosphere and atmosphere

3. 4.1.1.4 - Outline the significance of the different states of water on Earth in terms of water as:

   • Constituent of cells
     • Major component of cells - 70%
     • Functions as a medium for many chemical reactions in biological systems
       • Transporting necessary materials into cells
         • Photosynthesis: 6CO2(g) + 6H2O(l) --> C6H12O6(aq) + 6O2(g)     
         • Blood plasma
           • 80% water transports proteins, carbohydrates and hormones
         • Lungs
           • lined by water to facilitate movement of O2 into and CO2 out of blood
       • Removing waste products out from them
         • Respiration: C6H12O6(aq) + 6O2(g) --> 6CO2(g) + 6H2O(l)     
     • Transfer heat around body --> maintain body temperature of 37.4%
   • Habitat
     • Due to high heat capacity - absorb and release large quantities of heat energy with minute temperature changes
     • Organisms protected from rapid changes in temperature allowing surviva
     • Sea breezes at coastal cities --> reduce extreme temperatures inland
   • Weathering
     • weathering: the physical and chemical breakdown and decay of rocks
     • Physical weathering
       • Frost wedging
         • Water freezes --> expands --> rock cracks
       • Pounding of sea waves
         • Shapes coastal landscape
       • Erosion
         • Carrying away of dissolved ions, loose rock fragments and materials by rain and rivers from mountains to lower altitudes and eventually to the sea
     • Chemical weathering
       • Water react with or dissolve minerals in rocks
   • Natural Resource
     • Raising cattle, aquaculture, agriculture Domestic uses (cooking, hygiene, washing, boiling water)   Leisure (swimming) Transport (cargo ships, cruise ships) Industrial (solvent, cleaning agent, cooling agent) Hydro-electricity generation Habitat (fish, algae)     

4. PRACS

   • 4.1.2.1 - Perform an investigation involving calculations of the density of water as a liquid and a solid using density = mass / volume
   • 4.1.2.2 - Analyse information by using models to account for the differing densities of ice and liquid water
     • The density of a substance usually decreases as the temperature increases because more kinetic energy is being supplied. Therefore, the particles are spread out, creating a less dense substance
       • HOWEVER IN WATER
         • Structure of Liquid Water
           • Water molecules are randomly orientated  Overall structure of water is random     
         • Structure of Ice
           • Adjacent water molecules hydrogen bonding to form hexagonal clusters  Large vacant spaces within the hexagonal clusters --> there are less particles occupying the same amount of space     
         • Therefore ice is more dense than water
   • 4.1.2.3 - Plan and perform an investigation to identify and describe the effect of anti-freeze or salt on the boiling point of water

5. 4.1.1.1 - Define the terms solute, solvent and solution

   • Solute is what dissolves in a solvent to form a solution
   • Solute: the substance in a mixture that is dissolved
   • Solvent: the substance in a mixture that dissolves the other
   • Solution: a homogenous mixture of 2 or more substances where one is dissolved in the other

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