76 14. The DNA base thymine dissolves in water due to hydrogen bond- ing. Which of the following hydrogen bonds drawn between thy- mine and surrounding water molecules are valid? (LO 8.10) H H| H (IV) H H H (I)' (II) H H----:O: H H H H (III) H H (a) I and II (c) I, II, III (b) I, II, IV (d) III and IV

How do I (a) determine the energy change in the following reaction2 O2 + CH4→ CO2 + 2 H2Ogiven the following bond dissociation energies:C-C 340kJ/mol; C-H 420kJ/mol; O=O 490 kJ/mol; O-H 460 kJ/mol; C=O 720 kJ/mol. (b) Is the reaction exothermic or endothermic? Explaination?

Estimate ΔrH° for forming 2 mol ammonia from molecular nitrogen and molecular hydrogen. Is this reaction exothermic or endothermic?

7-45 (Chemical Connections 7C) A painkiller—for example, Tylenol—can be purchased in two forms, each containing the same amount of drug. One form is a solid coated pill, and the other is a capsule that contains tiny beads and has the same coat. Which medication will act faster? Explain.

Please explain

8:59 l LTE O AWhy are iron oxides in rocks evidence for prehistoric photosynthesis? (1 O Iron oxides form when oxygen, a product of photosynthesis, is in the atmosphere O Iron oxides form when cyanobacteria use carbon dioxide for photosynthesis. O Iron oxides form when carbon dioxide, a reactant of photosynthesis, is in the atmos O Iron oxides form when cyanobacteria produce oxygen via photosynthesis. O Type here to search esc

(Q52) Consider potassium bromide (KBr) in aqueous solution. (a) Which ion (K+ or Br-) will interact with the partial negative charge on the water molecule? (b) Which ion (K+ or Br-) will interact with the partial positive charge on the water molecule? (c) Which atom (H or O) in water has the partial positive charge? (d) Which atom (H or O) in water has the partial negative charge? (e) Water is a (polar or nonpolar) molecule?

The breaking of the O-O bond in peroxydisulfuryl difluoride (FO,SOOSO,F) gives FO,SO: (FO2SO)2 2 2 FO2SO The compound on the left of this equation is a colorless liquid that boils at 67.1°C. Its vapor, when heated to about 100°C, turns brown as the product of the reaction forms. Suppose that, in a sample of the vapor, the intensity of the brown color doubles between 100°C and 110°C and that the total pressure increases only by the 2.7% predicted for an ideal gas. Estimate AH° for the preceding reaction.

Explain how the calculated the Dihedral angle of the 2 methyle groups to be 90 degrees?

enow.com/ilrn/takeAssignment/takeCovalentActivity.do?locator%3Dassignment-take [References] Acetic acia is responsibie for the sour taste or vihegar. it can be manuracturea using the following reaction: |3| 2 CH3C-OH(g) 2 CH3C-H(g) + O2(g) Use tabulated values of bond energies from the table below to estimate AH for this reaction. Average Bond Energies Single Bonds Bond Bond Energy (kJ/mol) C-C 347 C-H 413 C-O 358 0-H 467 Multiple Bonds Bond Bond Energy (kJ/mol) C=0 1072 C=0 745 O=0 to 495 kJ %3D