chem test 2

Question 1

1st law of thermodynamics

Answer 1

internal energy of isolated system is constant, energy conserved, energy not created nor destroyed

Question 2

2nd law of thermodynamics

Answer 2

entropy tends to increase

Question 3

what is energy?

Answer 3

capacity to supply heat or do work

Question 4

what is kinetic energy?

Answer 4

energy of motion, when temperature raised the motion of the molecules goes up, heat or work can be done

Question 5

what is potential energy?

Answer 5

energy of position, stored energy, can become heat or work

Question 6

what is the universe composed of?

Answer 6

the system and the surroundings, when system absorbs energy surroundings must release energy

Question 7

what is 1st law thermo in mathematical terms?

Answer 7

delta E universe = 0, delta E system = - E surroundings, delta E = q + w where q = heat disorganized energy, something we feel and w = work organized energy, something we see

Question 8

delta E equation, and what does positive or negative delta E mean

Answer 8

E final - E initial
positive delta E means the system’s energy increased (ex heated water) and negative delta E means a system’s energy decreased (ex cooled water)

Question 9

in delta E work and heat equation, what does +q, -q, +w, -w mean?

Answer 9

positive q means heat is absorbed by the system (endothermic), negative q means heat given off by system (exothermic). positive w means work done ON system and negative w means work done BY the system

Question 10

formula for work

Answer 10

-delta ng (R)(T)

Question 11

what is delta ng?

Answer 11

n gas products - n gas reactants

Question 12

what is value of R to be used in work calculations with gases?

Answer 12

8.314 J * mol^-1 K^-1

Question 13

Kelvin conversion

Answer 13

Temperature in Celsius + 273.15

Question 14

when ng greater than 0 and when ng less than 0

Answer 14

expansion versus compression

Question 15

other r value to be used in later chapter 4

Answer 15

0.08206 L-atm/K-mol

Question 16

when to use what R value

Answer 16

for osmotic pressure calculations use 0.0821 L-atm/K-mol and for work calculations use 8.314 J/K-mol

Question 17

NUMBER ONE TIP

Answer 17

WRITE OUT UNITS AND KNOW THEMMM

Question 18

NUMBER 2 TIP

Answer 18

DO SIG FIGS CAREFULLY

Question 19

energy in constant volume

Answer 19

delta E is equal to the energy transferred as heat, qv, at constant volume w = 0 so delta E = q

Question 20

delta E = q+w 3 components

Answer 20

qv = heat at constant volume
qp = heat at constant pressure
-nRT = work at constant pressure

Question 21

what does qp in delta E = q+w lead to

Answer 21

delta H (enthalpy of reaction)

Question 22

delta H meaning

Answer 22

delta H > 0 endothermic
delta H < 0 exothermic

Question 23

equation with enthalpy and work at constant pressure

Answer 23

delta E = delta H +- nRT

Question 24

what is enthalpy of reaction?

Answer 24

heat absorbed by the reaction at constant pressure

Question 25

heat component of system

Answer 25

heat added to system can raise temperature or cause a phase change

Question 26

q = what

Answer 26

C delta T, where delta T = Tfinal - Tinitial and C = heat capacity, depends on amnt of material present units are J/C degree

Question 27

what is s

Answer 27

specific heat, heat capacity for 1 gram of a substance units are J/g degree C

Question 28

C = what

Answer 28

mass times specific heat

Question 29

q = what

Answer 29

C deltaT which = ms deltaT

Question 30

the higher the specific heat....

Answer 30

the more heat a substance can absorb WITHOUT changing its temperature

Question 31

endo vs exothermic change in temperature

Answer 31

endo thermic cause water temp to go down, exothermic cause water tempt to go up

Question 32

q reaction equal what

Answer 32

-qwater

Question 33

when heat causes phase change,

Answer 33

heat proportional to the number of moles present. temperature does not change.

Question 34

q = what for heat component of system change

Answer 34

q = n deltaH, heat of vaporization for liquid to gas or heat of fusion for solid to liquid

Question 35

specific heat units vs delta H units

Answer 35

s has units J/(g degree C) and delta H has units of kJ/mol

Question 36

msdeltaT versus ndeltaH units

Answer 36

first is in J, divide by 1000 to get kJ and ndeltaH is already in kJ

Question 37

potential energy order between phases

Answer 37

gas>>>liquid>solid

Question 38

standard state of pure substance

Answer 38

most stable form at 1atm pressure and specified temperature

Question 39

standard state of dissolved substsance

Answer 39

substance at concentration of 1M at 1atm and specific temperature

Question 40

in standard state, is there a standard temperature?

Answer 40

NO, AND IF NOT LISTED USE 298.15

Question 41

standard reaction enthalpies

Answer 41

reaction enthalpies in which all species are in their standard states

Question 42

standard heat of formation

Answer 42

enthalpy change for the reaction that produces one mole of substance from elements in standard state. per mol quantity.

Question 43

standard heat of combustion

Answer 43

enthalpty change for burning one mole of sbstance to produce co2 g and h2ol. per mol quantiity

Question 44

standard heat of atomization

Answer 44

enthalpy change for the breaking of all the bonds in molecule to produce atoms in gas phase. per mol quanitity

Question 45

standard heat of formation (delta h knot f)

Answer 45

enthalpy to produce 1 mole of a substance from its elements in their standard states, = 0 for any element in standard satte, listed in appendix b

Question 46

hess' law

Answer 46

delta H = sum c(product) x delta Hknot f (product) - sum c (reactant) x delta Hknot f (reactant) where C ARE THE COEFFICIENTS

Question 47

delta h UNITS

Answer 47

kj/mol of substance

Question 48

what happens at constant pressur ewith delta h and q

Answer 48

THEY ARE EQUAL

Question 49

how to tdetmerine heat sof formation from delta h comubustion

Answer 49

use back door, delta H comb = c product x delta hf - delta c x delta h f knot reactants

Question 50

what is d

Answer 50

bond eneryg, or bond dissociation energy (D0 is energy required to nbreak one mol of bonds in the gas phase, always POSITIVE ENDOTHERMIC

Question 51

d equation

Answer 51

delta h = summation #bonds broken x D (bonds proken) - summation formed bonds xd formed bond

Question 52

steps to write lewis structure

Answer 52

determine valence electrons, find central atom, make single bonds, add atoms to outer moleculse, make double or triple bonds if needed, double check and triple check structure!

Question 53

strategy with bond broken - bond formed

Answer 53

a) use bodn didssociation energies to get close to target reaction with everything in gas phase, then b) correct andy gas phase to proper slid or liuqid phase at 298K with hess' law

Question 54

DID U MEMORIZE SOLIDS LIQUIDS AND GASES IN PERIODIC TABLE?

Answer 54

im watching u...

Question 55

bonding order formula, example with SO2

Answer 55

#bonds/#bonding regions, example there are 3/2 = 1.5 BO

Question 56

in bomb calorimetry...

Answer 56

q is measured at constant VOLUME, no work done so q volum e= delta E, delta E = delta H -nRT

Question 57

bomb cali formula

Answer 57

qrxn= -qcal = -cal delta T cal, if the water is the only importnat portion, then qrxn = -mass water * s water * delta t water

Question 58

bomb cali equation with delta e and delta h

Answer 58

delta e comb = delta h comb - ngRT

Question 59

entropy formula elegante

Answer 59

write polynomial up to energy levels say 0,1,2,3 j = 1+x+x^2+x^3, raise to # moleucles, and look at coefficient of net energy