Understanding Water's Unique Properties: Tetrahedral and Disordered Structures, Slides of Microbiology

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New Views on Water Structure

Why does ice float?Why is water denser at 4C than at 0C?Why is water so difficult to heat?Why is water so difficult to compress?Why does water become less viscous, not more viscous, athigher pressures?Why do water molecules diffuse more easily, not less easily,at higher pressures

Why does ice float?Why is water denser at 4C than at 0C?Why is water so difficult to heat?Why is water so difficult to compress?Why does water become less viscous, not more viscous, athigher pressures?Why do water molecules diffuse more easily, not less easily,at higher pressures

Why does ice float?Why is water denser at 4C than at 0C?Why is water so difficult to heat?Why is water so difficult to compress?Why does water become less viscous, not more viscous, athigher pressures?Why do water molecules diffuse more easily, not less easily,at higher pressures

Why does ice float?Why is water denser at 4C than at 0C?Why is water so difficult to heat?Why is water so difficult to compress?Why does water become less viscous, not more viscous, athigher pressures?Why do water molecules diffuse more easily, not less easily,at higher pressures

New Views on Water StructureWater has both tetrahedral and disordered structures

3. Specific heat capacity is at a minimum at 35 °C but increases as thetemperature falls or rises, whereas the heat capacity of most otherliquids rises continuously with temperature. EXPLANATION:

Between 0 and 35°C, increasing the temperature steadily removes regions of ordered, tetrahedral structure, reducing water's ability toabsorb heat. Above 35 °C, so few of the tetrahedral regions are left thatwater behaves like a regular liquid. 4. Water's compressibility drops with increasing temperature until itreaches a minimum at 46°C, whereas in most liquids, thecompressibility rises continuously with temperature EXPLANATION:

As the temperature rises, the dense, disordered regions become more prevalent, and these are more difficult to compress. However,rising temperature also forces molecules within these regions further apartand hence makes them more compressible. This effect takes precedencebeyond 46 °C.

5. Water is particularly difficult to compressEXPLANATION:

The strong attraction between water molecules keeps them more closely packed than the molecules of many other liquids. This effect isparticularly marked when the higher-density disordered structure dominates 6. The speed of sound in water increases with temperature up to 74°C,after which it starts to fall againEXPLANATION:

This is the result of the interplay between water's unusual density and compressibility profiles, which directly stem from the changingbalance between the two types of structure. 7. Water molecules diffuse more easily, not less easily, at higherpressuresEXPLANATION:

High pressure converts more molecules to the disordered structure, in which they are more mobile.