Exam 1

Question 1

vmp

Answer 1

most probable speed.
occurs at the maximum in the distribution
the speed that has the greatest number of molecules

Question 2

vave

Answer 2

there are more molecules with high speed than low speed

vave>vmp

Question 3

vrms

Answer 3

speed is squared before taking average
More weight to high speeds
vrms>vave

Question 4

What happens as a reaction proceeds?

Answer 4

rate decreases as reactants are used up

Question 5

Why is a random walk a good model for behavior of gases?

Answer 5

Each collision causes a gas molecules to go in a new random direction

Question 6

What behavior is equivalent to taking a step?

Answer 6

A collision is equivalent to taking a step.

Question 7

What is the equivalent of the length of the step?

Answer 7

The length is the distance traveled between collisions and is equal to the mean free path

Question 8

What is the equivalent of the number of steps in the walk?

Answer 8

Collision frequency

Question 9

What does the steady state approximation assume about the concentration of I during a reaction?

Answer 9

d[I]/dt = 0

[I] is constant

Question 10

What must be true about the relative magnitudes of the two rate constants for the steady state approximation to be true?

Answer 10

k2»k1
[I] will be low and fairly constant

if k1»k2 [I] will be a maximum then decrease => never constant

Question 11

Does the viscocity of a liquid increase, decrease, or stay constant as the temp is increased?

Answer 11

Decrease
Viscosity in liquids is due to attractive forces between molecules
higher temp => greater KE => easier to overcome attractive forces

Question 12

Does the viscosity of a gas increase, decrease of stay constant as the temp is increased?

Answer 12

Increase
Viscosity in gases is due to transfer of momentum due to molecular collisions
higher temp => greater speed => more momentum to transfer

Question 13

Consider a mixture of helium and CO2. Which type of collision will occur with the greatest total collision frequency?

Answer 13

Between small fast ‘bullets’ (He) and big slow ‘targets’ (CO2)

Question 14

km

Answer 14

measures binding of enzyme to substrate

larger km=> worse binding

Question 15

kcat

Answer 15

measures how effective enzyme is at creating product and ‘turning over’ free enzyme once enzyme and substrate are bound

Question 16

vmax (enzyme)

Answer 16

fastest rate possible
Occurs at very high substrate concentration
proportional to kcat

Question 17

I vmax is unchanged by inhibitor concentration, would you expect the inhibitor to bind to the same binding site on the enzyme as the substrate of to a different size?

Answer 17

Inhibitor must be interfering with binding => binding at same site
vmax unchanged => enzyme’s ability to convert enzyme to product once bound is unaffected
with enough substrate, rate is as fast as without inhibitor