Biology - Water 2.0 / 5 based on 1 rating ? BiologyBiological molecules, organic chemistry and biochemistryASOCR Created by: AneesiiCreated on: 07-04-13 16:45 Define cohesion. The attractive force that holds water molecules together by hydrogen bonding. 1 of 9 Explain surface tension. Water molecules on the surface are pulled downwards by attractive forces (cohesion), resulting in the surface molecules packing together more tightly. 2 of 9 Describe the structure of a water molecule. 2 hydrogen atoms covalently bonded to one oxygen atom. The bonds between the hydrogen and oxygen atoms form a permanent dipole. 3 of 9 Define hydrogen bonding. A strong dipole-dipole attraction between an electron deficient hydrogen atom on one molecule and a highly electronegative atom on another. 4 of 9 How and why would NaCl dissolve in water? HOW: The Na+ and Cl- ions separate because they are slightly attracted by the dipoles in water molecules. WHY: NaCl is an ionic compound. 5 of 9 Why is ice less dense than water? The molecules are held apart in an open lattice by the hydrogen bonds. 6 of 9 What is urea? The main nitrogenous excretory product. 7 of 9 How does sweat work? it absorbs the heat energy from the surface of the skin as it evaporates. 8 of 9 Latent heat is...? The amount of heat energy absorbed by a substance, without raising its temperature, as it changes from one state to another 9 of 9
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