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Description
Flashcards by emma_moran, updated more than 1 year ago
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Created by emma_moran
over 10 years ago
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| Question | Answer |
| Why is water a liquid? | Hydrogen bonds are weak and are easily broken. Hydrogen boding creates a fluid as molecules constantly change partners. |
| Why is water a powerful solvent of NaCl? | Sodium chloride is a lattice of sodium (Na+) ions ionically bonded to chloride (Cl-) ions. The delta + hydrogen atoms of water are attracted to the Cl- ions, while the delta - oxygen atoms are attracted to the Na+ ions. The lattice is pulled apart and the salt dissolves in the water. |
| Why is water a universal solvent of polar molecules? | All polar molecules and ions are water soluble because they can form hydrogen bonds with water. Ions ad polar molecules can move/interact freely and take part in cellular chemical reactions. |
| Why can't water dissolve non-polar molecules? | Non-polar molecules have no electrical charge so they cannot form hydrogen bonds with water. Non-polar molecules repel water molecules and are thus hydrophobic. |
| Hydrophobic | Repels water |
| Hydrophilic | Attracts water |
| Amphiphilic | Has hydrophobic and hydrophilic properties |
| How does surface tension arise? | Water molecules in water are surrounded by water molecules and being attracted equally in all directions, which results in a net force of zero. However water molecules at the surface of the water are not completely surrounded by other water molecules, which results in them being pulled inwards. This creates some internal pressure and forces liquids to contract at the surface. |
| How surfactant prevents atelectasis in premature babies? | Sometimes premature babies are born with adhesive atelectasis, which is when there is a deficiency of surfactant in the lungs. When water forms a surface with air, the water on the surface is always attempting to contract (surface tension). Epithelial cells in the alveoli secrete surfactant, a surface active agent, which greatly reduces surface tension. Surfactant therefore prevents the alveoli from collapsing due to the surface tension of the water present in the alveoli. |
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