notes from class January 30th

notes from class January 30th - Summary to date The...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Summary to date The stoichiometry of the balanced reaction determines the relative rates of disappearance of reactants and appearance of products. •a A + b B cC + dD The experimental rate law describes the dependence of the initial rate on the concentration of the reactants The experimental rate law gives us clues as to how the reaction proceeds. We can use it to test proposed reaction mechanisms. The experimental rate law rate=k[A] n [B] m tells us how the rate of the reaction depends on the concentrations of the reactants and sometimes products of a reaction. n is the reaction order for A m is the reaction order for B and n + m is the overall reaction order.        11 1 1 dA dB dC dD ad t bd t cd t d d t 
Background image of page 1

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

View Full DocumentRight Arrow Icon
What is k? It is the rate constant for the reaction. It is independent of reactant concentration but does depend on temperature. All the experiments must be done under identical conditions. It tells us something about the energy required for the reaction to go, the activation energy. It also includes an “orientation factor”. More later Now determine the value and units of k. 8.0 x 10 -4 molL -1 /s = k(.1 molL -1 )(.1 molL -1 )((.1 molL -1 ) 2 ) -4 -1 -1 -3 -1 -4 -1 4 8x10 molL s k= =8 mo lL s 1x10 (molL )
Background image of page 2
The order of a reactant might not always be a whole number. Example: A + B C Experiment [A], mol/L [B], mol/L Rate, mol/Ls 1 .010 .010 2.4 x10 -2 2 .020 .010 4.8 x 10 -2 3 .020 .020 .136 rate = k[A] m [B] n Looking at experiments 1 and 2, Doubling the [A] doubles the rate. Therefore, Rate = k[A] 1 [B] n What is n? mn -2 -1 -1 -1 -1 m n n k(.2) (.1) 4.8x10 molL s = .136 molL s k(.2) (.2) 1 .352941176 = 2 ln(.352941176) = nln.5 n=1.5    It doesn’t matter which logarithm you use.
Background image of page 3

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

View Full DocumentRight Arrow Icon
For the reaction 2 NO( g ) + 2 H 2 ( g )
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 16

notes from class January 30th - Summary to date The...

This preview shows document pages 1 - 5. Sign up to view the full document.

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