CHEM237 Study Guide - Final Guide: Methanol, Dystrophin, Immunoglobulin G

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cerisemole687

5 Apr 2012

School

University of Waterloo

Department

Chemistry

Course

CHEM237

Professor

Joseph Guillemette

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Document Summary

Fe involved in the transport of oxygen and in redox enzymes. Cu, z, se, co are important at the active site of certain enzymes. Used to determine whether a physical process is possible. Enthalpy: h, measure of heat evolved during a reaction. Free energy: g, measure of the tendency for a process to occur. Bioenergetics: study of energy transformation in living organisms. 2nd law -> spontaneous processes are characterized by the conversion of order to disorder. Entropy increases as the temperature rises (k is dependent on temperature) Atp + h2o = adp + pi exothermic. Atp + h2o = amp + pi exothermic. Exergonic because of resonance stabilization, electrostatic repulsion, smaller solvation energy. Oxygen has a partial charge of -0. 82 and hydrogen has a partial charge of +0. 41. Causes a permanent dipole moment of 1. 85 debye units. Hvap is the energy needed to break intermolecular interactions, increases as mw increases. H bonds -> 1. 8a long, strongest when oh-o is co-linear.

Related Questions

a statement of the first law of thermodynamics is that a. in a spontaneous process, the entropy of the universe increases b. there is no disorder in a perfect crystal at 0 k. c. the total energy of the universe is constant. d. the totla energy of the universe is constant. e. mass and energy are conserved in all chemical reactions

Which of the following is favorable for a process to occur from a thermodynamics point of view? (Choose all that are correct)

		-Increasing enthalpy
		-Decreasing enthalpy
		-Increasing entropy
		-Decreasing entropy
		-Increasing Gibbs free energy
		-Decreasing Gibbs free energy

Photosynthesis is the process by which plants effectively capture energy from the sun and store it for later use by organisms. It's the fundamental process that enables the entire food chain. Actual photosynthesis is a highly complex process involving many steps and many different chemicals, but we can get an idea of what's happening to thermodynamic quantities (enthalpy, Gibbs free energy, and entropy) using simpler reactions.

Let's consider a toy model in which an input of energy (for example from the sun) is be used to combine water and carbon dioxide to create an organic molecule (formaldehyde) and oxygen, effectively "storing" that energy for use later. The simplest possible such process is given by:

CO₂ + H₂O â O₂ + CH₂O

The table lists the enthalpy of formation, ÎH_f and the entropy S for 1 mol of each of the substances involved in this reaction at 298 K and 10⁵ Pa.

	ÎH_f (kJ)	S (kJ/K)
CH₂O	-115.9	0.2189
H₂O	-241.82	0.1888
CO₂	-393.51	0.2138
O₂	0	0.2051

Answer the following questions assuming that 1 mol of formaldehyde molecules are formed.

1. What is the change in enthalpy of this reaction?
ÎH = ____ kJ

Does this change in enthalpy represent energy that must be added to the system, or energy that is released from the system?
-Energy must be added or Energy is released?

2. What is the change in entropy for this reaction?
ÎS = ____ kJ/K

Does the entropy increase or decrease?
-Entropy increases or Entropy decreases?

At 298 K, what is the heat transfer that corresponds to this change in entropy?
Q = ____ kJ
Does this heat transfer represent energy that is added to the system, or energy that is released from the system?
--Energy is added Energy is released ?

3. What is the change in Gibbs free energy for this reaction?
ÎG = _____ kJ

The Gibbs free energies of formation, ÎG_f, are: -228.57 kJ for water; -394.36 kJ for CO₂; and 0 kJ for O₂. What is the Gibbs free energy of formation for formaldehyde?
ÎG_f (formaldehyde) = _______ kJ

4. Using the formation of formaldehyde as a model, comment on photosynthesis and the formation of sugars using what we know about entropy and free energy.

CHEM237 Study Guide - Final Guide: Methanol, Dystrophin, Immunoglobulin G

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