# Physical Constants and Tables

Physical Constants

 Constant Symbol Value Avogadro's number N 6.02214 x 1023 mol-1 Boltzmann constant k 1.38066 10-23 J/K Faraday's constant F 96.485 kJ/volt 96,485 C/mol Gas constant R 8.31451 J/K mol 0.08206 L atm/K mol Planck's constant h 6.62608 x 10-34 J s Speed of light c 2.99792458 x 108 m/s

SI Prefixes for Units

 Prefix Symbol 10n Decimal Short scale Long scale yotta Y 1024 1000000000000000000000000 Septillion Quadrillion zetta Z 1021 1000000000000000000000 Sextillion Trilliard exa E 1018 1000000000000000000 Quintillion Trillion peta P 1015 1000000000000000 Quadrillion Billiard tera T 1012 1000000000000 Trillion Billion giga G 109 1000000000 Billion Milliard mega M 106 1000000 Million kilo k 103 1000 Thousand hecto h 102 100 Hundred deca da 101 10 Ten 100 1 One deci d 10-1 0.1 Tenth centi c 10-2 0.01 Hundredth milli m 10-3 0.001 Thousandth micro 10-6 0.000001 Millionth nano n 10-9 0.000000001 Billionth Milliardth pico p 10-12 0.000000000001 Trillionth Billionth femto f 10-15 0.000000000000001 Quadrillionth Billiardth atto a 10-18 0.000000000000000001 Quintillionth Trillionth zepto z 10-21 0.000000000000000000001 Sextillionth Trilliardth yocto y 10-24 0.000000000000000000000001 Septillionth Quadrillionth

Conversion Factors

 work: joule J work done by accelerating 1 g at 1 cm/sec2 for 1 m 1 J = 9.869 x 10-3 L atm 1000 J = 1 kJ 1018 J = 1 EJ (exajoule) mass/energy Joule J energy in mass units (for E=mc2) 1 J = 1 kg m-2 s-2 work electron volt eV energy to accelerate 1 electron by 1 volt of potential difference 1 eV = 1.1602 x 10-19 J heat: calorie cal heat needed to raise the temperature of 1 g of H2O by 1 deg C 1 cal = 4.184 J 1000 cal= 1 kcal heat: British thermal unit BTU heat needed to raise the temperature of 1 lb of H2O by 1 deg F 1 BTU = 1.055 kJ power: watt W rate at which the energy, in joules, is delivered 1 W = 1 J/sec 1000 W = 1 kW other kilowatt hours kWh 1 kilowatt delivered over 1 hour 1 kWh = 3.6 x 106 J other wavenumber cm-1 1/wavelength of electromagnetic radiation 1 cm-1 = 0.01196 kJ/mol other Hertz s-1, Hz frequency of electromagnetic radiation 1 s-1 = 3.99 x 10-13 kJ/mol mass atomic mass unit amu mass of proton 1.6605 x 10-27 kg pressure atmosphere atm atmospheric pressure at sea level 101.325 kilopascals 760 torr (mm Hg) 14.7 psi 1.01325 bar

 Temperature: Farenheit Water freezes at 32 deg F and boils at 212 deg F (at 1 atm). Celsius or centigrade Water freezes at 0 deg C and boils at 100 deg C (at 1 atm). (Tdeg C x 9/5) + 32 = Tdeg F Kelvin This is the absolute scale. At 0 K, molecular motion is zero. TK = Tdeg C + 273.15

Periodic Table

Ionization Energies
 Electron configuration Ionization Reaction Energy Required [He]2s1 Li Li+ + e- 520 kJ/mol [He]2s2 Be Be+ + e- 899 kJ/mol [He]2s22p1 B B+ + e- 800 kJ/mol [He]2s22p2 C C+ + e- 1090 kJ/mol [He]2s22p3 N N+ + e- 1400 kJ/mol [He]2s22p4 O O+ + e- 1310 kJ/mol [He]2s22p5 F F+ + e- 1680 kJ/mol [He]2s22p6 Ne Ne+ + e- 2080 kJ/mol

Atomic Orbital Ionization Energies

Electronegativity and Electron Affinity

The electron affinity is the heat released (negative energy term) when a free electron combines with a neutral atom to make a negatively charged ion.
 F + e- F- -328 kJ/mol Cl + e- Cl- -349 kJ/mol Br + e- Br- -324 kJ/mol I + e- I- -295 kJ/mol

Here is a periodic table that includes the electron affinities. Note that the numbers are in kJ of energy released and should be negative numbers. By convention, energy added to a system has a positive value and energy released from a system has a negative value.

Electronegativity is a property of atoms within molecules rather than free atoms. It measures the tendency of that atom to draw bonding electrons towards itself.

Bond Dissociation Energies

 O2 498 kJ/mol O3 364 kJ/mol HO-OH 142 kJ/mol HO-H 459 kJ/mol H3C-H 435 kJ/mol
 ON-O 300 kJ/mol O2N-O 190 kJ/mol Cl-Cl 253 kJ/mol H2N-NH2 160 kJ/mol N2 941 kJ/mol

Average Bond Energies

 molecule kJ/mol molecule kJ/mol molecule kJ/mol molecule kJ/mol H—F 565 N—N 160 I—Cl 208 C ≡ C 839 H—Cl 427 N—F 272 I—Br 175 O = O 495 H—Br 363 N—Cl 200 C=O in CO2 799 C = O 745 H—I 295 N—Br 243 S—H 347 C ≡ O 1072 N—O 201 S—F 327 N = O 607 C—H 413 O—H 467 S—Cl 253 N = N 418 C—C 347 O—O 146 S—Br 218 N ≡ N 941 C—N 305 O—F 190 S—S 266 C ≡ N 891 C—O 358 O—Cl 203 C = N 615 C—F 485 O—I 234 Si—Si 340 C=C 614 C—Cl 339 Si—H 393 C—Br 276 F—F 154 Si—C 360 C—I 240 F—Cl 253 Si—O 452 C—S 259 F—Br 237 Cl—Cl 239 Cl—Br 218 Br—Br 193

Enthalpies of Formation

 molecule kJ/mol molecule kJ/mol molecule kJ/mol O 249.17 O3 142.7 H2O(g) -241.82 H2O(l) -286 H2O2(l) -187.78 H 217.97 N 472.70 NO(g) 90.25 N2O(g) 82.05 NO2(g) 33.18 NO3(g) 78.9 HNO3(g) -124.2 SO2(g) -296.83 SO3(g) -395.72 H2SO4 -719 H2S(g) -20.63 SF4(g) -753.0 SF6(g) -1209 Cl 121.68 HCl(g) -92.31 HOCl -71.5 ClO2(g) 99.0 C(g) 716.68 CO(g) -110.53 CO2(g) -393.51 CH4 -78.81 CH3 145.69 C2H6 -84.68 C2H4 52.26 C2H2 226.73 C3H8 -82.4 C3H6 52.3 C4H10 -126.5 1-butene C4H8 20.4 butadieneC4H6 175.8 C5H12 -114.9 C6H14 -130.1 CH3OH -190.1 CH3CH2OH -217.1 CH2O -104.9 glucoseC6H12O6 -1271 sucroseC12H22O11 -2226 riboseC5H10O5 -1051 arabinoseC5H10O5 -1058

Acid Dissociation Constants

For all acids (HA) listed here, the dissociation reaction is:

 HA + H2O H+(aq) + A-(aq) Ka = [H+(aq)] [A-(aq)]/ [HA] pKa = -log Ka

 Name Formula pKa Perchloric acid HClO4 -10 Hydroiodic acid HI -10 Hydrobromic acid HBr -9 Hydrochloric acid HCl -7 Hydrofluoric HF 3.17 Sulfuric acid H2SO4 -3 Bisulfate ion HSO3- 1.99 Nitric acid HNO3 -1.5 Trifluoroacetic acid CF3C(O)OH 0.5 Fluoroacetic acid CFH2C(O)H 2.6 Trichloroacetic acid CCl3C(O)OH 0.77 Dichloroacetic acid CCl2HC(O)OH 1.25 Chloroacetic acid CClH2C(O)OH 2.86 Benzoic acid PhC(O)OH 4.2 Formic acid HC(O)OH 3.75 Acetic acid CH3C(O)OH 4.8 Phenol PhOH 10.0 Water H2O 15.7 Hydronium H3O+ -1.7 Methanol CH3OH 15.5 Ethanol CH3CH2OH 15.9 1-methylethanol (CH3)2CHOH 17.1 1,1-dimethylethanol (CH3)3COH 18 Hydrogen sulfide H2S 7.0 Ammonium NH4+ 9.24 Ammonia NH3 38 Protonated acetone (CH3)2C=O-H+ -7 Carbonic acid H2CO3 3.6 Bicarbonate ion HCO3- 10.3

Acid Dissociation Constants for Polyprotic Acids
 Acid Name Ka pKa Carbonic, H2CO3 1st 4.5 x 10-7 6.35* 2nd 4.7 x 10-11 10.33 Hydrogen sulfide, H2S 1st 9.5 x 10-8 7.02 2nd 1.0 x 10-19 19.0 Phosphoric acid, H3PO4 1st 7.1 x 10-3 2.15 2nd 6.3 x 10-8 7.20 3rd 4.5 x 10-13 12.35 Sulfuric acid, H2SO4 1st large 2nd 1.2 x 10-2 1.92 Telluric acid, H6TeO6 1st 2.0 x 10-8 7.7 2nd 1.0 x 10-11 11.0 3rd 3.0 x 10-15 14.5 Sulfurous acid, H2SO3 1st 1.2 x 10-2 1.92 2nd 6.6 x 10-8 7.18 Selenous acid, H2SeO3 1st 3.5 x 10-3 2.46 2nd 5.0 x 10-8 7.3 Tellurous acid, H2TeO3 1st 3.0 x 10-3 2.5 2nd 2.0 x 10-8 7.7 Ascorbic acid, H2C6H6O6 1st 7.9 x 10-5 4.10 2nd 1.6 x 10-12 11.79 Citric acid, H3C6H5O7 1st 7.1 x 10-4 3.15 2nd 1.7 x 10-5 4.77 3rd 6.4 x 10-6 5.19

* Includes the hydration equilibrium between CO2(aq) and H2CO3.

Gas Solubility Constants

Solubility Product Constants
 Mineral Equation Ksp calcium carbonate CaCO3 Ca+2 + CO32- 3.8 x 10-9 calcium hydroxide Ca(OH)2 Ca+2 + 2 HO- 5.0 x 10-6 calcium phosphate Ca3(PO4)2 3 Ca+2 + 2 PO43- 1 x 10-26 hydroxyapatite Ca5(PO4)3(OH) 5 Ca+2 + 3 PO43- + HO- 1 x 10-36 fluoroapatite Ca5(PO4)3F 5 Ca+2 + 3 PO43- + F- 1 x 10-60 aluminum hydroxide Al(OH)3 Al3+ + 3 HO- 3 x 10-34 aluminum phosphate AlPO4 Al3+ + PO43- 9.8 x 10-21 iron(II) carbonate FeCO3 Fe+2 + CO3-2 3.1 x 10-11 iron(II) sulfide FeS Fe+2 + S-2 8 x 10-19

Specific Heat

For any pure substance, there is a specific quantity of heat energy required to increase the temperature of 1 gram of the substance by 1 degree. This is called the specific heat or heat capacity.

q = m x C x T

Specific Heat at 25 deg C
 substance C (J g-1 deg-1) air 1.01 copper 0.385 ethanol 2.44 hydrogen 14.3 silica 0.703 water 4.18

Standard reduction half cell potentials

 Reductio Reaction Potential, V F2 + 2 e- 2 F- 2.87 Co+3 + e- Co+2 1.82 H2O2 + 2 H+ + 2 e- 2 H2O 1.78 PbO2 + 4 H+ + SO42- + 2 e- PbSO4 + 2 H2O 1.69 MnO4- + 4 H+ + 3 e- MnO2 + 2 H2O 1.68 PbO2 + 4 H+ + 2 e- Pb+2 + 2 H2O 1.46 Cl2 + 2 e- 2 Cl- 1.36 Cr2O72- + 14 H+ + 6 e- 2 Cr+3 + 7 H2O 1.33 O2 + 4 H+ + 4 e- 2 H2O 1.23 Ag+ + e- Ag 0.800 Fe+3 + e- Fe+2 0.77 I2 + 2 e- 2 I- 0.54 Cu+ + e- Cu 0.52 Cu+2 + e- Cu+ 0.16 gluconic acid + 2 H+ + 2 e- glucose + H2O 0.050 [Fe(CN)6]3- + e- [Fe(CN)6]4- 0.436 2 H+ + 2 e- H2 0.000 Pb+2 + 2 e- Pb -0.13 Ni+2 + 2 e- Ni -0.23 PbSO4 + 2 e- Pb + SO42- -0.35 H2O + e- 1/2 H2 + OH- -0.415 Zn+2 + 2 e- Zn -0.76 CO2 + e- CO2- -1.84 Na+ + e- Na -2.71 Li+ + e- Li -3.04

Log Table

Professor Patricia Shapley, University of Illinois, 2011