Water Notes
8.4 Water
8.4.1 Water is distributed on Earth as a solid, liquid and gas y y
y
Define the terms solute, solvent and solution Solution a homogeneous mixture of two or more substances Solute a substance that is dissolved in another substance or the component of a solution present in a lower amount. Solvent a substance which can dissolve another substance or the component of a solution present in a greater amount. Identify the importance of water as a solvent Water is essential as a reactant and a solvent in the cycling of C, O, N, P and S in nature. It also allows biological processes to occur in aqueous solutions and serves as a transport system for nutrients and waste products in living organisms. Compare the state, percentage and distribution of water in the biosphere, lithosphere, hydrosphere and atmosphere Biosphere 70% Liquid Lithosphere Variable Liquid Water of crystallisation Solid ice Hydrosphere 96-100% Liquid Solid ice Atmosphere 0-5% gas
Percentage of water State of water
y
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 Water is the predominant constituent of cells, functioning as: A solvent for biochemical reactions that sustain life C6H12O6 (aq) + 6O2 (g) Photosynthesis : 6CO2 (g) + 6H2 O (l) Respiration : C6H12O6 (aq) + 6O2 (g) 6CO2 (g) + 6H2O (l) A raw material for metabolism (e.g. in plants) A transport medium for nutrients and wastes A thermal buffer that resists large temperature fluctuations A habitat in which temperature extremes are less than nearby terrestrial habitats Water serves as a natural habitat for many organisms Major advantage: temperatures vary much less in water than on land Therefore marine animals are protected from experiencing temperature extremes An agent of weathering of rocks As water freezes and thaws repeatedly, the stress due to expansion and contraction
8.4.1 Water is distributed on Earth as a solid, liquid and gas y y
y
Define the terms solute, solvent and solution Solution a homogeneous mixture of two or more substances Solute a substance that is dissolved in another substance or the component of a solution present in a lower amount. Solvent a substance which can dissolve another substance or the component of a solution present in a greater amount. Identify the importance of water as a solvent Water is essential as a reactant and a solvent in the cycling of C, O, N, P and S in nature. It also allows biological processes to occur in aqueous solutions and serves as a transport system for nutrients and waste products in living organisms. Compare the state, percentage and distribution of water in the biosphere, lithosphere, hydrosphere and atmosphere Biosphere 70% Liquid Lithosphere Variable Liquid Water of crystallisation Solid ice Hydrosphere 96-100% Liquid Solid ice Atmosphere 0-5% gas
Percentage of water State of water
y
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 Water is the predominant constituent of cells, functioning as: A solvent for biochemical reactions that sustain life C6H12O6 (aq) + 6O2 (g) Photosynthesis : 6CO2 (g) + 6H2 O (l) Respiration : C6H12O6 (aq) + 6O2 (g) 6CO2 (g) + 6H2O (l) A raw material for metabolism (e.g. in plants) A transport medium for nutrients and wastes A thermal buffer that resists large temperature fluctuations A habitat in which temperature extremes are less than nearby terrestrial habitats Water serves as a natural habitat for many organisms Major advantage: temperatures vary much less in water than on land Therefore marine animals are protected from experiencing temperature extremes An agent of weathering of rocks As water freezes and thaws repeatedly, the stress due to expansion and contraction