Chapter 2 .docx

Chapter 2 .docx - Chapter 2 Water 1 Does water have a...

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Chapter 2: Water 1. Does water have a higher boiling point, heat of vaporization, and surface tension then other common solvents? a. Yes 2. What are the unusual properties of water? a. High b.p.,m.p., heat of vaporization, surface tension b. Bent structure makes it polar c. Non-tetrahedral bond angles d. H-bond donor and acceptor e. Potential to form four H-Bonds per water molecule 3. What is the heat of vaporization of chloroform and water? a. Chloroform is 247 J/G b. Water is 2260 j/g 4. What is the H2O bond angel? a. 104.5 degrees 5. what is the h2O bond angle due to? a. The outer electron orbitals of the oxygen atom 6. What is the charge on the partial charge on the hydrogen and what is the partial charge on the oxygen? In H2O a. Oxygen has a partial negative b. Hydrogen has a partial positive 7. What is a hydrogen bond? a. A hydrogen bond is a electrostatic attraction between the O atom of one molecule and the H of another. This provides the cohesion to make water a liquid at room temperature 8. How does hydrogen bonds compare to covalent, ionic and van der waals attractions? a. Hydrogen bonds are longer but weaker then covalent bonds or ionic bonds, but they are stronger than van der waals interactions. 9. What are the bond dissociation energies for the types of bonds listed above? a. 470 kJ/mol covalent b. 23 kJ/mol hydrogen c. 0.1-.05 kJ/mol van der waals interactions 10. how many hydrogen bonds can each water molecule form in ice, and what is the lifetime of the bond? a. 4 hydrogen bonds and 10 microseconds 11. In liquid how many hydrogen bonds can each water molecule form and what is the lifetime of each bond? a. Approximately 3.4 hydrogen bonds and the lifetime is 10 picoseconds 12. What is the reason ice is less dense then liquid water? a. This is due to the crystal lattice structure of the ice, so the ice floats on the water 13. What are 2 methods that can increase the entropy of a system? a. Melting or evaporation 14. What kind of process is melting or evaporating?
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a. This is a spontaneous process 15. What is needed to form a hydrogen bond? a. A electronegative atom like oxygen or nitrogen, becaease they are hydrogen acceptor with a lone pair of electrons, and a another hydrogen bond to another electronegative atom which is the hydrogen donor 16. Hydrogen bonds are directional, in which direction is the attraction the strongest? a. The attraction is the strongest when the 3 bonds involved in the bond are linear 17. Are polar molecules hydrophilic or hydrophobic? a. Hydrophilic 18. What kind of effect causes protein folding, formation of lipid micelles and binding of steroid hormones to their receptor?
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