Test 3 De-BriefingTest 3 De-BriefingOverall Averages:Overall Averages:

66thth Hour Hour 88thth Hour Hour Last YearLast Year

64%64% 70%70%67%67%

(No gases)(No gases)

Test corrections due Thursday

Part 1: MCPart 1: MC

66thth Hour Hour 88thth Hour Hour

AverageAverage 60.4%60.4% 64.0%64.0%

DistributionDistribution

Hi Hi ScoresScores

Jackson (81.3)Jackson (81.3)NickNick

MickieMickie

Zach (90.7)Zach (90.7)SydneySydney

BlaiseBlaise

0 13

69

0

2

4

6

8

10

A's B's C's D's F's

1 1

45

7

0

1

2

3

4

5

6

7

8

A's B's C's D's F's

MC TroublespotsMC Troublespots

#1 Right idea, wrong shape…#1 Right idea, wrong shape…

#5 A way to simplify: Remember molar #5 A way to simplify: Remember molar volume at STP?volume at STP?

#7 A way to organize:#7 A way to organize:Xe(g)Xe(g) ++ FF22(g)(g) XeFXeF??(s)(s)

BeforeBefore 1.7 atm1.7 atm 8 atm8 atm 00

AfterAfter 00 2.92.9 1.71.7

ChangeChange 1.71.7 5.15.1 1.71.7

More MC TroublesMore MC Troubles

#12-16. Rats#12-16. Rats

#17-18. Rats again.#17-18. Rats again.

Thermochemistry = Thermochemistry = #22 – Think stoich#22 – Think stoich

#26-28 – How do concentration and heat #26-28 – How do concentration and heat affect rate???affect rate???

#30 – If double 1#30 – If double 1stst order, rate will… order, rate will…

#31 – A Visual Initial Rates Method#31 – A Visual Initial Rates Method

ExperimentExperiment Initial [X]Initial [X](mol L(mol L-1-1))

Initial [Y]Initial [Y](mol L(mol L-1-1))

Initial Rate of Initial Rate of Formation Formation

of Zof Z(mol L(mol L-1-1 min min-1-1))

11 0.100.10 0.300.30 4.0 × 104.0 × 10-4-4

22 0.200.20 0.600.60 16 × 1016 × 10-4-4

33 0.200.20 0.300.30 4.0 × 104.0 × 10-4-4

Part 2: Quantitative Free ResponsePart 2: Quantitative Free Response66thth Hour Hour 88thth Hour Hour

AverageAverage 62%62% 71.5%71.5%

DistributionDistribution

Hi ScoresHi ScoresJackson (89%)Jackson (89%)

Nick & MichelleNick & MichelleAllisonAllison

Blaise (97%)Blaise (97%)DedicDedic

NikkiNikki

01

6

4

8

A's B's C's D's F's

32

3

5

3

A's B's C's D's F's

First HalfFirst Half

#1 – OK#1 – OK

#2a – Forgot to do stoich! #2a – Forgot to do stoich!

Mols BMols B22HH66 → ? Mols H→ ? Mols H22??

#2c – Eh?#2c – Eh?

#2d - #2d - #2e – Stoich w/heat!#2e – Stoich w/heat!

#2f - OK#2f - OK

BH3 - Borane

B2H6 – DiboraneCrazy, huh?

#3 – Method of Initial Rates#3 – Method of Initial Rates

3a&b - 3a&b - 3c – Units?3c – Units?

3d – Eh? More stoich!3d – Eh? More stoich!

6 H6 H22O from 1 BO from 1 B22HH66

3e – Not bad.3e – Not bad.

#4 – Integrated Rate Laws#4 – Integrated Rate Laws

Ugg. As in Ugg-ly. Ugg. As in Ugg-ly. But some bright spotsBut some bright spotsa)a) OKOKb)b) Slope? (OK, it was an ugly graph, too. Slope? (OK, it was an ugly graph, too.

I’m sorry)I’m sorry))c)c

d)d) BHBH33 is made from B is made from B22HH66 already reacted, already reacted, not what Bnot what B22HH66 is still left is still left

e)e) A little disappointingA little disappointing

Part 3: Qualitative FRPart 3: Qualitative FR

66thth Hour Hour 88thth Hour Hour

AverageAverage 57 /7857 /78

73%73%

58.4 /7858.4 /78

79%79%

DistributionDistribution

Hi Hi ScoresScores

Nick (95%)Nick (95%)MickieMickie

Jackson & Jackson & ChristianChristian

Zach (95%)Zach (95%)BlaiseBlaise

ConnourConnourNikki & BradNikki & Brad

4

23

54

A's B's C's D's F's

2

6

23 3

A's B's C's D's F's

Question 1a Possible Answers…Question 1a Possible Answers…What’s Wrong?What’s Wrong?

More moles He cuz atoms are smaller, so More moles He cuz atoms are smaller, so more are needed to fill space.more are needed to fill space.

Does size matter when it comes to how Does size matter when it comes to how much can fit?much can fit?

Hed = 62 pm

SF6

d = 380 pmSpace per particle

d = 4,400 pm

Another Common Answer to 1aAnother Common Answer to 1a

He has the lowest molar mass, so need He has the lowest molar mass, so need more.more.

What’s wrong? What’s wrong?

Is mass the same for all flasks?Is mass the same for all flasks?

PV = nRT: take it for a spin.PV = nRT: take it for a spin.

1B1B

Kinetic energy has TWO factors:Kinetic energy has TWO factors:

KE = ½ mvKE = ½ mv22

Mass AND Velocity!Mass AND Velocity!

Nevertheless, a gas’s kinetic energy depends Nevertheless, a gas’s kinetic energy depends ONLY on its ___________.ONLY on its ___________.

(A gas’s particles will “adjust” their velocity to (A gas’s particles will “adjust” their velocity to achieve this kinetic energy)achieve this kinetic energy)

1B1B

Can a charging rhinoceros and a charging mouse Can a charging rhinoceros and a charging mouse have the same kinetic energy?have the same kinetic energy?

MassMass

Top Top SpeedSpeed

(m/s)(m/s)

Kinetic Kinetic EnergyEnergy

(Joules)(Joules)

RhinoRhino 2000 kg2000 kg 1515

(~35 mph!)(~35 mph!)

225,000225,000

MouseMouse 0.030 kg0.030 kg ?? 225,000225,000

Answer: Yes, if the mouse is traveling 3,800 m/s (8,700 mph, Mach 11)!

2a2a

Methane = CHMethane = CH44 (I feel only a little bad) (I feel only a little bad)CatalysisCatalysis is the process in which the rate of a chemical reaction is is the process in which the rate of a chemical reaction is

either increased or decreased by means of a either increased or decreased by means of a chemical chemical substancesubstance known as a known as a catalystcatalyst. Unlike other reagents that . Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by participate in the chemical reaction, a catalyst is not consumed by

the reaction itself.the reaction itself. … …Catalysts work by providing an (alternative) Catalysts work by providing an (alternative) mechanism involving a different transition state and lower activation mechanism involving a different transition state and lower activation

energyenergy.. - Wikipedia (emphasis on - Wikipedia (emphasis on

“chemical substance” added)“chemical substance” added)A spark is NOT a catalyst, it is energy…A spark is NOT a catalyst, it is energy…

2b2b

Mole fraction = mols of Gas A / Total mols Mole fraction = mols of Gas A / Total mols of gasof gas

Partial pressure = mol fraction Partial pressure = mol fraction × Total × Total pressurepressure

3a-c3a-c

More Q3More Q3

3d = 3d = 3e = Look down there3e = Look down there

3f = 3f =

Follow me to Lab 11 Results

3g3g

For 1For 1stst order reactions order reactionsPlot [A] vs. time: slope = RatePlot [A] vs. time: slope = Rate

Plot ln[A] vs. time: slope = -kPlot ln[A] vs. time: slope = -k

Failure of integrated rate law to tell rate:Failure of integrated rate law to tell rate:

ln[A] = -kt + ln[A]ln[A] = -kt + ln[A]00 RATE?

A Word About FinalsA Word About Finals

66thth Hour: Friday 8:15 – 10:05 Hour: Friday 8:15 – 10:05 In my room (Room 105)In my room (Room 105) Will (quietly) leave during 6Will (quietly) leave during 6thth hour Final Period hour Final Period

88thth Hour: Thursday 12:25 – 2:15 Hour: Thursday 12:25 – 2:15 In my room (Room 105)In my room (Room 105) Will leave during 7Will leave during 7thth hour class hour class

Feel free to drop in for extra help Feel free to drop in for extra help

(just not during 1(just not during 1stst, 2, 2ndnd, or 3, or 3rdrd Final periods) Final periods)