Lecture 13

Lecture 13 - New Science and Engineering Graduate School in New York City Mayor Bloomberg is offering free land and $100M in infrastructure

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
New Science and Engineering Graduate School in New York City Mayor Bloomberg is offering free land and $100M in infrastructure spending Columbia building a new $450M building for neuroscience in Manhattanville Campus 1 Remember: Hour exam Wed Nov 9 Reading assignment: Chapter 9
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
The Characteristics of Chemical Equilibrium Two possible reasons reactant and product concentrations remain stable: 1. System is at chemical equilibrium (thermodynamics) 2. Forward and reverse reactions are proceeding VERY slowly (kinetics) Haber reaction proceeds at 500 C, yet is infinitely slow at room temperature. N 2 (g) + 3 H 2 (g) 2 NH 3 (g) 500 o C Stoichiometry sets relative rates
Background image of page 2
The Equilibrium Constant aw of Mass Action (initially an empirical result) Law of Mass Action (initially, an empirical result) jA + kB lC + mD [] [ ] ] lm k CD K B = jk AB Equilibrium constant for forward reaction Brackets denote concentration; These are concentrations at equilibrium Note, that K will have different units depending on stoichiometry of reaction aw of Mass Action is true regardless of microscopic mechanism (kinetics) of reaction Law of Mass Action is true regardless of microscopic mechanism (kinetics) of reaction For the reverse reaction: 1 ' ] [ ] K D K = = For the forward reaction with stoichiometry different by a constant: jA + nkB lC + nmD [ ] '' nl nm n nj nk K K == njA nkB nlC + nmD
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Past history of system does not affect equilibium For the reaction H 2 (g) + I 2 (g) 2HI (g), consider two possibilities using the same rigid container: (1) you add 0.5 mol of each reactant, allow the system to come to equilibrium; then you add another mole of H 2 , and allow the system to reach equilibrium again, or g, (2) you add 1.5 mol H 2 and 0.5 mol I 2 and allow the system to come to equilibrium Which equilibrium mixture will have more H 2 : (a) the first one prepared (b) the second one prepared (c) they have the same amount of H 2 . hen reactants and products are added is NOT important to equilibrium conditions When reactants and products are added is NOT important to equilibrium conditions Equilibrium independent of past history of sample 4
Background image of page 4
Reaction Quotient, Q N 2 (g) + 3 H 2 (g) 2 NH 3 (g) 2 30 3 [] ] NH Q H = vs. 2 3 3 ] NH K H = 20 NH 22 Q = K : System is at equilibrium. Concentrations will remain the same. Q > K : Too much product. System will shift to left (consuming products, rming reactants) to get to equilibrium forming reactants) to get to equilibrium Q < K : Too much reactant. System will shift to right (consuming reactants, forming products) to get to equilibrium 5
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Calculating equilibrium concentrations or pressures: Small Equilibrium Constants q Allows a convenient simplification of the mathematics Gaseous NOCl decomposes to form the gases NO and Cl . At 35 o C the equilibrium constant is 1.6 x NOCl(g) NO(g)+Cl ) 2 10 -5 . In an experiment in which 1 mole of NOCl is placed in a 2.0L flask, what are the equilibrium
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/03/2011 for the course MATH 1090 taught by Professor Greenwood during the Spring '08 term at MIT.

Page1 / 21

Lecture 13 - New Science and Engineering Graduate School in New York City Mayor Bloomberg is offering free land and $100M in infrastructure

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online