S10_Student_Lecture_04

# S10_Student_Lecture_04 - Announcements 1/25/2010 Lab this...

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Announcements 1/25/2010 Lab this week: A Chemical Oscillation Reaction HW04 released which means HW03 is due on Friday Iclicker points are posted Go Colts! Yes! Go Saints! ??

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Be careful to state what species is being used to express the rate: S 2 O 3 2- + 2H + SO 2 + H 2 O + S We could say: rate = - [S2O3]/ t or rate = - [H+]/ t Quantitative Descriptions but [_____]/ t = 1/2 x [_____]/ t OR [___]/ t = 2 x [_______]/ t Choose [ S 2 O 3 2- ] as a point of reference since its coefficient is 1. For every molecule of S 2 O 3 2- that disappears, 2 molecules of H+ disappear, so [ S O ] is
Expressing Rate in Terms of Changes in Concentration with Time 2H 2 ( g ) + O 2 ( g ) 2H 2 O( g ) (a) Express the rate in terms of changes in [H 2 ], [O 2 ], and [H 2 O] with time. (b) When [O 2 ] is decreasing at 0.23 mol/L*s, at what rate is [H 2 O] increasing? Choose [O 2 ] as a point of reference since its coefficient is 1. For every molecule of O 2 that disappears, 2 molecules of H 2 disappear and 2 molecules of H 2 O appear, so [O 2 ] is disappearing at half the rate of change of H 2 and H 2 O.

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aA + bB cC + dD The numerical value of the rate depends upon the substance that serves as the reference. The rest is relative to the balanced chemical equation. Caution: We will use rate but specify with respect to what.
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## This note was uploaded on 02/21/2010 for the course CHEM 116 taught by Professor Stevenson during the Spring '08 term at Purdue.

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S10_Student_Lecture_04 - Announcements 1/25/2010 Lab this...

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