Standart Oluşum Entalpileri Pekçok reaksiyonun entalpisi ya doğrudan ya da dolaylı yoldan elde edilir. Türlerin standart oluşum ısıları tablolaştırılırsa, herhangi bir tepkimenin reaksiyon ısısı deneysel bir çalışmaya gerek duyulmaksızın hesaplanabilir. Bir bileşiğin standart oluşum entalpisi, \rm \Delta H_f^o, elementlerinin referans hallerinden, bileşiğin oluşum için gerekli standart reaksiyon entalpisidir. Bir elementin referans hali özel bir sıcaklıkta ve 1 atm. basınçtaki en kararlı halidir (bazen standart basınç 1 bar olarak kabul edilir.). Örneğin; 298 K de azotun referans hali N2 moleküllerinin gaz olduğu durumdur. Civa referans halinde sıvı, karbon ise grafit formundadır. kalay için ise beyaz metalik şeklidir. Standart oluşum entalpisi bileşiğin molü başına entalpi olarak tanımlanır. 298 K de sıvı benzenin oluşumu için; \rm 6C_{grafit} \; + \; 3H_{2(g)} \; \rightarrow \; C_6H_{6(s)} reaksiyonu yazılabilir ve değeri +49.0 kJ mol-1 dir. Elementlerin standart oluşum entalpileri referans hallerinde tüm sıcaklıklarda sıfırdır. \rm N_{2(g)} \; \rightarrow \; N_{2(g)} \qquad \qquad \Delta H_f^o = 0.0 \; kJ. Tablo 1 de bazı maddelerin oluşum entalpilerinin verilmiştir. Tablonun kullanımına ilişkin bir örneği, etilenin 25 oC deki hidrojenasyonu için ele alalım. \rm CH_2CH_{2(g) } \; + \; H_{2(g)} \; \rightarrow \; CH_3CH_{3 (g)} Tablodan \rm \Delta H_f^o (CH_2CH_{2(g)}) = 52.25 \; kJ, \rm \Delta H_f^o (H_{2(g)}) = 0.00 \; kJ ve \rm \Delta H_f^o (CH_3CH_{3(g)}) = -84.68 \; kJ, olarak bulunabilir. Böylece reaksiyona eşlik eden reaksiyon entalpisi \rm \Delta H_{298}^o = \Delta H_f^o (CH_3CH_{3(g)}) - ( \Delta H_f^o (CH_2CH_{2(g)} + \Delta H_f^o (H_{2(g)} ) \rm \Delta H_{298}^o = (-84.68 \; kJ) - ( (52.25 \; kJ) + 0.00 \; kJ ) = -136.93 \; kJ Reaksiyon için hesaplanan bu entalpi etilenin hidrojenasyonu değerini gösterir.   Tablo 1 : Saf maddelerin molar termodinamik özelikleri. Formül \rm \Delta H_f^o kJ mol-1 \rm \Delta G_f^o kJ mol-1 \rm S^o J mol-1 K-1 \rm C_p^o J mol-1 K-1 Ag(c) 0 0 42.55 25.351 Ag(g) 284.55 245.65 172.997 20.786 Ag+(g) 1021.73 -- -- -- Ag2CO3(c) -505.8 -436.8 167.4 112.26 Ag2O(c) -31.05 -11.2 121.3 65.86 Ag2S(c,argenit) -32.59 -40.67 144.01 76.53 AgCN(c) 146 156.9 107.19 66.73 AgCNS(c) 87.9 101.39 131 63 AgCl(c,cerargyrite) -127.068 -109.789 96.2 50.79 AgBr(c) -100.37 -96.9 107.1 52.38 AgI(c) -61.83 -66.19 115.5 56.82 AgNO3(c) -124.39 -33.47 140.92 93.05 Ag3PO4(c) -- -879 -- -- Ag2CrO4(c) -731.74 -641.76 217.6 142.26 Ag2SO4(c) -715.88 -618.41 200.4 131.38 Al(c) 0 0 28.33 24.35 Al(g) 326.4 285.7 164.54 21.38 Al3+(g) 5483.17 -- -- -- Al(OH)3 -1276 -- -- -- AlCl3(c) -704.2 -628.8 110.67 91.84 AlCl3(g) -583.2 -- -- -- Al2O3(c,alumina) -1675.7 -1582.3 50.92 79.04 B(c) 0 0 5.86 11.09 BF3(g) -1137 -1120.35 254.01 50.46 BaCO3(c,witherite) -1216.3 -1137.6 112.1 85.35 BaC2O4(c) -1368.6 -- -- -- BaCrO4(c) -1446 -1345.22 158.6 -- BaF2(c) -1207.1 -1156.8 96.36 71.21 BaSO4(c) -1473.2 -1362.2 132.2 101.75 Bi(c) 0 0 56.74 25.52 Bi2S3(c) -143.1 -140.6 200.4 122.2 Br2(l) 0 0 152.231 75.689 Br2(g) 30.907 3.11 245.463 36.02 Br(g) 111.88 82.429 174.91 20.786 Br-(g) -219.07 -- -- -- C(c,grafit) 0 0 5.74 8.527 C(c,elmas) 1.895 2.9 2.377 6.113 C(g) 716.682 671.257 158.096 20.838 CO(g) -110.525 -137.168 197.674 29.42 CO2(g) -393.509 -394.359 213.74 37.11 COCl2(g,fosgen) -218.8 -204.6 283.53 57.66 CH4(g,methane) -74.81 -50.72 186.264 35.309 C2H2(g,asetilen) 226.73 209.2 200.94 43.93 C2H4(g,eten) 52.25 68.12 219.45 43.56 C2H6(g,etan) -84.68 -32.82 229.6 52.63 C3H6(g,propen) 20.2 62.72 266.9 64 C3H8(g,propan) -104.5 -23.4 269.9 7 C4H10(g,n-bütan) -126.5 -17.15 310.1 97.4 C5H12(g,n-pentan) -146.5 -8.37 348.9 120.2 C8H18(g,octane) -208.5 16.4 466.7 189 CH3OCH3(g) -184.05 -112.59 266.38 64.39 CH3OH(g,metanol) -200.66 -162 239.7 43.89 CH3OH(l,metanol) -238.66 -166.36 126.8 81.6 C2H5OH(g,etanol) -235.1 -168.49 282.7 65.44 C2H5OH(l,etanol) -277.69 -174.78 160.7 111.46 CH3COOH(l,acetic acid) -484.51 -389.9 159.8 124.3 (CH3)2O(g) -184.05 -112.59 266.38 64.39 CH3CHO(l) -192.3 -128.2 160.2 -- CH3Cl(g) -80.83 -57.37 234.58 40.75 CHCl3(g) -103.14 -70.34 295.71 65.69 CCl4(l) -135.44 -65.27 216.4 131.75 C6H6(g,benzen) 82.9 129.7 269.2 81.6 C6H6(l,benzen) 49 124.7 172 132 C6H12(l,siklohekzan) -156.3 26.7 204.4 157.7 CaO(c) -635.09 -604.03 39.75 42.8 Ca(OH)2(c) -986.09 -898.49 83.39 87.49 CaCO3(c, calsit) -1206.92 -1128.79 92.9 81.88 CaCO3(c, aragonit) -1207.13 -1127.75 88.7 81.25 CaC2O4(c) -1360.6 -- -- -- CaF2(c) -1219.6 -1167.3 68.87 67.03 Ca3(PO4)2(c) -4109.9 -3884.7 240.91 231.58 CaSO4(c,anhydrit) -1434.11 -1321.79 106.7 99.66 Cd(c) 0 0 51.76 25.98 Cd(g) 2623.54 -- -- -- Cd2+(g) 112.01 77.41 167.746 20.786 Cd(OH)2(c) -560.7 -473.6 96 -- CdS(c) -161.9 -156.5 64.9 -- Cl2(g) 0 0 223.066 33.907 Cl(g) 121.679 105.68 165.198 21.84 Cl-(g) -233.13 -- -- -- ClO2(g) 102.5 120.5 256.84 41.97 Cu(c) 0 0 33.15 24.35 Cu(g) 338.32 298.58 166.38 20.786 CuC2O4(c) -- -661.8 -- -- CuCO3.Cu(OH)2 (c,malachite) -1051.4 -893.6 186.2 -- Cu2O(c,cuprit) -168.6 -146 93.14 63.64 CuO(c,tenorit) -157.3 -129.7 42.63 42.3 Cu(OH)2(c) -449.8 -- -- -- Cu2S(c,kalkosit) -79.5 -86.2 120.9 76.32 CuS(c,kovellit) -53.1 -53.6 66.5 47.82 F2(g) 0 0 202.78 31.3 F(g) 78.99 61.91 158.754 22.744 F-(g) -255.39 -- -- -- Fe(c) 0 0 27.28 25.1 Fe(g) 416.3 370.7 180.49 25.677 Fe2+(g) 2749.93 -- -- -- Fe3+(g) 5712.8 -- -- -- Fe0.9470 (c,wuestite) -266.27 -245.12 57.49 48.12 Fe2O3(c,hematit) -824.2 -742.2 87.4 103.85 Fe3O4(c,magnetit) -1118.4 -1015.4 146.4 143.43 Fe(OH)3(c) -823 -696.5 106.7 -- Fe3C(c,sementit) 25.1 20.1 104.6 105.9 FeCO3(c,siderit) -740.57 -666.67 92.9 82.13 FeS(c,pirrhotit) -100 -100.4 60.29 50.54 FeS2(c,pyrite) -178.2 -166.9 52.93 62.17 H2(g) 0 0 130.684 28.824 H(g) 217.965 203.247 114.713 20.784 H+(g) 1536.202 -- -- -- H2O(g) -241.818 -228.572 188.825 33.577 H2O(l) -285.83 -237.129 69.91 75.291 H2O2(g) -136.31 -105.57 232.7 43.1 H2O2(l) -187.78 -120.35 109.6 89.1 H2S(g) -20.63 -33.56 205.79 34.23 H2SO4(l) -813.989 -690.003 156.904 138.91 HF(g) -271.1 -273.2 173.779 29.133 HCl(g) -92.307 -95.299 186.908 29.12 HBr(g) -36.4 -53.45 198.695 29.142 HI(g) 26.48 1.7 206.594 29.158 HCN(g) 135.1 124.7 201.78 35.86 Hg(l) 0 0 76.02 27.983 HgCl2(c) -224.3 -178.6 146 -- Hg2Br2(c) -206.9 -181.075 218 -- Hg2Cl2(c) -265.22 -210.745 192.5 -- HgS(c, kırmızı) -58.2 -50.6 82.4 48.41 HgS(c, siyah) -53.6 -47.7 88.3 -- Hg2SO4(c) -743.12 -625.815 200.66 131.96 I2(c) 0 0 116.135 54.438 I2(g) 62.438 19.327 260.69 36.9 I(g) 106.838 70.25 180.791 20.786 I-(g) -197 -- -- -- ICl(g) 17.78 -5.46 247.551 35.56 K(c) 0 0 64.18 29.58 K(g) 89.24 60.59 160.336 20.786 K+(g) 514.26 -- -- -- KF(c) -567.27 -537.75 66.57 49.04 KCl(c) -436.747 -409.14 82.59 51.3 KBr(c) -393.798 -380.66 95.9 52.3 KI(c) -327.9 -324.892 106.32 52.93 KClO4(c) -432.75 -303.09 151 112.38 KNO3(c) -494.63 -394.86 133.05 96.4 Mg(c) 0 0 32.68 24.89 Mg2+(g) 2348.504 -- -- -- MgF2(c) -1123.4 -1070.2 57.24 61.59 MgCO3(c,magnesit) -1095.8 -1012.1 65.7 75.52 Mg(OH)2(c) -924.54 -833.51 63.18 77.03 Mn(c,à) 0 0 32.01 26.32 MnO2(c) -520.03 -465.14 53.05 54.14 MnS(c, yeşil) -214.2 -218.4 78.2 49.96 N2(g) 0 0 191.61 29.125 N(g) 472.704 455.563 153.298 20.786 NH3(g) -46.11 -16.45 192.45 35.06 NH4Cl(c) -314.43 -202.87 94.6 84.1 NO(g) 90.25 86.55 210.761 29.844 NO2(g) 33.18 51.31 240.06 37.2 N2O(g) 82.05 104.2 219.85 38.45 N2O4(g) 9.16 97.89 304.29 77.28 N2O4(l) -19.5 97.54 209.2 142.7 N2O5(g) 11.3 115.1 355.7 84.5 N2O5(c) -43.1 113.9 178.2 143.1 NOCl(g) 51.71 66.08 261.69 44.69 NOBr(g) 82.17 82.42 273.66 45.48 Na(c) 0 0 51.21 28.24 Na(g) 107.32 76.761 153.712 20.786 Na+(g) 609.358 -- -- -- NaF(c) -573.647 -543.494 51.46 46.86 NaCl(c) -411.153 -384.138 72.13 50.5 NaBr(c) -361.062 -348.983 86.82 51.38 NaI(c) -287.78 -286.06 98.53 52.09 Na2CO3(c) -1130.68 -1044.44 134.98 112.3 NaNO2(c) -358.65 -284.55 103.8 -- NaNO3(c) -467.85 -367 116.52 92.88 Na2O(c) -414.22 -375.46 75.06 69.12 NiS(c) -82 -79.5 52.97 47.11 O2(g) 0 0 205.138 29.355 O3(ozone) 142.7 163.2 238.93 39.2 O(g) 249.17 231.731 161.055 21.912 P(c,white) 0 0 41.09 23.84 P(g) 314.64 278.25 163.193 20.786 PH3(g) 5.4 13.4 210.23 37.11 PCl3(g) -287 -267.8 311.78 71.84 PCl5(g) -374.9 -305 364.58 112.8 Pb(c) 0 0 64.81 26.44 Pb(g) 195 161.9 175.373 20.786 PbBr2(c) -278.9 -261.92 161.5 80.12 PbCl2(c) -359.41 -314.1 -136 -- PbO(c,red) -218.99 -189.93 66.5 45.81 PbO(c,sarı,litharge) -217.32 -187.89 68.7 45.77 PbO2(c) -277.4 -217.33 68.6 64.64 Pb3O4(c) -718.4 -601.2 211.3 146.9 Pb(OH)2(c) -- -452.2 -- -- PbS(c,galen) -100.4 -98.7 91.2 49.5 PbSO4(c) -919.94 -813.14 148.57 103.207 S(c,rombik) 0 0 31.8 22.64 S(c,monoklinik) 0.33 -- -- -- S(g) 278.805 238.25 167.821 23.673 SF6(g) -1209 -1105.3 291.82 97.28 SO2(g) -296.83 -300.194 248.22 39.87 SO3(g) -395.72 -371.06 256.76 50.67 SO3(l) -441.04 -373.75 113.8 -- SO2Cl2(g) -364 -320 311.94 77 Sn(c,white) 0 0 51.55 26.99 Sn(c,grey) -2.09 0.13 44.14 25.77 SnO(c) -285.8 -256.9 56.5 44.31 SnO2(c,kassiterit) -580.7 -519.6 52.3 52.59 SnS(c) -100 -98.3 77 49.25 Tl(c) 0 0 64.18 26.32 Tl+(g) 777.764 -- -- -- Tl3+(g) 5639.2 -- -- -- Zn(c) 0 0 41.63 25.4 Zn2+(g) 2782.78 -- -- -- ZnO(c) -348.28 -318.3 43.64 40.25 ZnS(c, vürtzit) -192.63 -- -- -- ZnS(c, sefehalerit) -205.98 -201.29 57.7 46