New User Special Price Expires in

Let's log you in.

Sign in with Facebook


Don't have a StudySoup account? Create one here!


Create a StudySoup account

Be part of our community, it's free to join!

Sign up with Facebook


Create your account
By creating an account you agree to StudySoup's terms and conditions and privacy policy

Already have a StudySoup account? Login here


by: Carmela Kilback


Carmela Kilback
GPA 3.92


Almost Ready


These notes were just uploaded, and will be ready to view shortly.

Purchase these notes here, or revisit this page.

Either way, we'll remind you when they're ready :)

Preview These Notes for FREE

Get a free preview of these Notes, just enter your email below.

Unlock Preview
Unlock Preview

Preview these materials now for free

Why put in your email? Get access to more of this material and other relevant free materials for your school

View Preview

About this Document

Class Notes
25 ?




Popular in Course

Popular in Chemistry

This 6 page Class Notes was uploaded by Carmela Kilback on Wednesday September 9, 2015. The Class Notes belongs to CHEM 452 at University of Washington taught by Staff in Fall. Since its upload, it has received 7 views. For similar materials see /class/192601/chem-452-university-of-washington in Chemistry at University of Washington.


Reviews for PHYS CHEM BIOC I


Report this Material


What is Karma?


Karma is the currency of StudySoup.

You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!

Date Created: 09/09/15
UNITS Almost everything will be in SI units I like asking eXam questions about units and the conversion of units mass 7 kilograms kg distance 7 meters m time 7 seconds s force 7 newtons N kgms2 energy quotworkquot 7joules J Nm power 7 watt W Js pressure 7 pascal Pa Nmz volume 7 liter L 10393 m3 electric charge 7 coulomb C electrostatic potential 7 volts V Jc sometimes cf constants gas constant Avogadro s Number Speed of lightvacuum Speed of sound Planck s constant density of water Boltzmann s constant Charge of an electron R 8314 JmoleK NA 7 602 x1023 c 30 X 108 ms Z 330 ms h 7 662 x1034 Js h h bar h2TE as in the physics dept cafe p 1 gml 1 gcc k 138 x1023 JK e 7 1602 x10 C Gravitational acceleration on Earth g 98 ms2 ATP hydrolysis mathematical constants TE 314159 e 27183 In X 2303 log10X AG 7 310 x 104 Jmol 310 ldmol Both X and y are unitless in both y ln X and X ey 2 lna ln Ha handy conversions 1 calorie 1 cal 4184 J 1 atmosphere 1 atm 1013 X 105 Pa 760 torr 760 mmHg 1 erg 7 10397 J 1 inch 254 cm K C 27315 C 7 F3259 1 kg weighs about 22 lb different units mass vs force This data is from Smith Cui and Bustamante Science 271 792 1996 and from Cui and Bustamante PNAS 97 127132 2000 There is recent data available as well this is an area of current research As an example of the second relationship above Mickey Schurr39s lab here at UW has worked with bacterial plasmids circular DNA When the DNA is joined in a circle it can be twisted in a positive or negative direction which is called supercoiling e g telephone cord One parameter that describes the supercoiling is the linking number I which is the number of turns of one strand around the other The linking number for a relaxed circular DNA is lg Mickey39s lab found the work to change the linking number for a particular plasmid p305 which is N 4800 bp RTconst 2 2 k z 1 war Number of base pairs a a In this case the action of the spring is in its twist rather than its extension Work in an Electrical Field We will cover the beautiful subject of electricity and voltage only briefly here in 3 short acts 1 Charge and Voltage 2 Current and Voltage 3 Resistance and Voltage Charge and Voltage A common way to separate proteins and different lengths of DNA is by electrophoresis The amount of force depends on the charge of each molecule IFelectricl 2 QB where Q 2 charge Coulombs and E 2 electric field Iworkl szorce distance 2 QEd as long as both Q and E are independent of distance d Equipment for electrophoresis will rarely tell you what the electric field is between its electrodes but it will often tell you what the voltage drop V sometimes called E is between the electrodes That s fine because V 2 Ed So Iworkl QV Example DNA is a highly charged molecule with one negative charge every 17 nm of its length Typical lengths are from microns in Viruses to centimeters in humans Because of this charge electrophoresis is used to separate different lengths of DNA A nice description can be found in Physical Chemistry by Raymond Chang University Science Books p 906 Current and Voltage N ow consider batteries If you look at the side of a battery it will tell you how many volts it discharges In this case we don t know what the charge is but we easily measure the current across the leads Current 2 I chargetime Qt units Amps Coulombsec Then Iworkl QV ItV IVt 6 2008 Sarah L Keller Example TSampW Ex 23 3rd EdTSWampP Ex 24 4 h Ed How much work is done by a 12 V battery which discharges 01 A for 1 hour Iworkl I Vt 3600 01A12V1 h0uri hour 2 432 103J Now what sign is it It is work done by the system so battery work 432 k Example Ion Channels Open ion channels behave as conducting wires through a membrane A typical current of a large channel is 1nA A typical open time is lms this unit of time which is very common in biological processes How many mono valent ions go through the channel each time it opens Charge 2 Current time Q 2 It 2 1 nA1 ms 2 10 9 A10 3 s 10 12 Coulombs The charge on an electron or on a mono valent ion is e 16 x 10 19 Coulombs So the number of ions 2 10 12 Coulombs 16 x 10 19 Coulombsion 6 x 106 ions That s a lot of ions to go through a teeny 10nm x 10nm hole in a millisecond Resistance and Voltage What if you connect a resistor of a known value for example a light bulb between the leads of a battery How much work is done in 1 hour You don t know how much current ows but you do know the resistance R of the resistor 2 v IR so I VR and Iwork Vt t PHOTONS AND BLACKBODY RADIATION Even if two systems are not in contact with each other and are not in thermal equilibrium they can still exchange radiation Each photon carries an energy of Ephoton hD where h Planck s constant 2 6626 x 10 34 Is and E h2 rl39 1054 x 10 34 Js and 1 is the frequency of the light s l which are the same thing as Hertz 2 Hz Blackbodies are ideal systems that radiate and absorb all wavelengths e g the sun or a glowing ember of coal The energy radiated by a blackbody is highly dependent on its temperature T4 An energy ux is the energy J that passes through some area m2 for some particular time s radiation energy Energy ux o T4 area time where 6 is the StefanBoltzmann constant 2 567 x 10 8 J m2sK4 7 2008 Sarah L Keller FRICTION Some of the mechanical work described above can be lost to friction This is relevant to not only engines but to biological systems as well In some cases the system works best with little friction engines and blood flow and in some cases with friction maximized brake shoes and gecko toes Friction is an irreversible process The energy is dissipated into heat not all of which is recaptured by the system We often disregard friction in this class but that doesn t mean it is not important PRESSURE VOLUME WORK IDEAL GAS Consider changing the volume of gas inside of a small balloon or piston P external Pt al in em gt x 1 work I force dx What is the force due to pressure Think about the units Fpressure pressure area 1 Iworkl Ipressura area dx av pressure W V V jPV dV V In some cases P will be a constant but not always In general pressure is a function of V What about the sign There is always a negative sign in this equation no matter if there is expansion or compression of the gas Here is one way to see it In an expansion against a constant external pressure Pextemal is a positive number and Vf is greater than Vi Work is being done by the system so work needs to end up negative so we add a negative sign at the front Which pressure do we use If the piston is changing position by the gas expanding then it is pushing against the external pressure and that is the relevant P to plug in If the gas is under compression the piston is pushing against the internal pressure Pimemal 8 2008 Sarah L Keller Here is a summary of different circumstances we will enounter when calculating pressure volume work 0 Free Expansion P 13 ext 0 Constant Volume dV 2 0 Constant External Pressure P 13 ext constant Reversible ExpansionCompression Pext 13 int constant 0 Ideal PV 2 nRT n2 0 van der Waals P a7 V nb nRT Irreversible Expansion P 13 final constant Example 1 Free Expansion expanding into a volume against no opposing pressure V work jPV dV M V IO dV 0 Note this is irreversible 14 Example 2 Constant Volume V V work JPV dV jPV 0 0 VA 4 Example 3 A gas is expanded from 1 L to 2 L against a constant external pressure of 1 x 105Pa about latm What is the work done by the system Since 13 exlemal 1 x 105Pa constant then the integral above becomes simply V work J39PVdV M V Iemmrm V eAw w 1105Po 2L 1L 103 3 1105Pa1L m 1L 1 102 J Note that the sign makes sense because the system has done work on the surroundings and its energy decreases 9 2008 Sarah L Keller Example 4 Reversible isothermal expansion or compression of an ideal gas with a constant number of moles In this case reversible implies that 13 inlemal 13 external P which is t a constant throughout the expansion or compressionf Ideal gas means PV 2 nRT Isothermal and a constant number of moles means that nRT is a constant The first thing we always do is write down our integral for work V work JPVdV V What do we substitute in for PV Pressure is no longer a constant Instead we use P nRTV V V RT work JPVdV I 4 V V V V dV nRT jd V nRTln f v V V As an example find the work to compress an ideal gas from 2L to 1L with Pfinal 1 x 105Pa From the equation above work nRT ln12 but what do we plug in for nRT We have not been given the temperature or the number of moles However we do know that PV 2 nRT a constant PVPiViPfo nRT 3 3 1105PaL lo m 1L 11on Substitute the value of nRT in the equation for work above 39 work 1 102 1102Jln2 1 11102Jln2 1102Jln2 A small aside on reversibility We will see later that in general reversible processes allow the maximum amount of work to be done If we wanted to get work out of a system of compressed gas which we subsequently allowed to expand we d get more out of the system that had been compressed and expanded reversibly A small aside on ideal gases In an ideal gas the molecules do not interact so the internal energy of the gas does not depend on whether the molecules are near each other in a small volume or far from each other in a large volume The internal energy is independent of volume and depends only on temperature which we write as ET Later we will discuss how internal energy E relates to work w 10 2008 Sarah L Keller


Buy Material

Are you sure you want to buy this material for

25 Karma

Buy Material

BOOM! Enjoy Your Free Notes!

We've added these Notes to your profile, click here to view them now.


You're already Subscribed!

Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'

Why people love StudySoup

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"

Janice Dongeun University of Washington

"I used the money I made selling my notes & study guides to pay for spring break in Olympia, Washington...which was Sweet!"

Steve Martinelli UC Los Angeles

"There's no way I would have passed my Organic Chemistry class this semester without the notes and study guides I got from StudySoup."


"Their 'Elite Notetakers' are making over $1,200/month in sales by creating high quality content that helps their classmates in a time of need."

Become an Elite Notetaker and start selling your notes online!

Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.