قيمة الثابت العام للغازات

‫)‪(157‬‬
‫ﺍﻟﻔﺼﻞ ﺍﻟﺜﺎﻧﻲ ‪ :‬ﻗﻮﺍﻧﲔ ﺍﻟﻐﺎﺯﺍﺕ‬
‫إﻋﺪاد د‪ /‬ﻋﻤﺮ ﺑﻦ ﻋﺒﺪ اﷲ اﻟﮭﺰازي‬
‫ﻗﻴﻤﺔ ﺍﻟﺜﺎﺑﺖ ﺍﻟﻌﺎﻡ ﻟﻠﻐﺎﺯﺍﺕ‬
‫‪Value of the Gas Constant‬‬
‫ﻻ ﺗﺘﻐﯿﺮ اﻟﻘﯿﻤﺔ اﻟﻌﺪدﯾﺔ ﻟﻠﺜﺎﺑﺖ )‪ (R‬إﻻ ﺑﺎﺧﺘﻼف اﻟﻮﺣﺪات اﻟﺘﻲ ﯾﻘﺎس ﺑﮭﺎ ﻛﻞ ﻣﻦ‬
‫اﻟﻀﻐﻂ )‪ (P‬واﻟﺤﺠﻢ ﻓﻘﻂ )‪ .(V‬وﻋﻨﺪ اﻟﺘﻌﺎﻣﻞ ﻣﻊ ﻗﻮاﻧﯿﻦ اﻟﻐﺎزات ﯾﺘﻢ اﻟﺘﻌﻮﯾﺾ ﺑﻘﯿﻤﺔ ‪R‬‬
‫اﻟﻤﻨﺎﺳﺒﺔ ﻓﻲ ﺿﻮء اﻟﻮﺣﺪات اﻟﻤﺘﺎﺣﺔ‪.‬‬
‫وﻣﻦ اﻟﺴﮭﻞ اﺷﺘﻘﺎق وﺣﺪات ﺛﺎﺑﺖ اﻟﻐﺎزات ﻋﻠﻰ اﻟﻨﺤﻮ اﻟﺘﺎﻟﻲ ‪:‬‬
‫‪PV‬‬
‫‪pressure × (length)3‬‬
‫=‪R‬‬
‫=‬
‫‪nT‬‬
‫‪degrees × moles‬‬
‫‪force × (length)-2 × (length)3‬‬
‫‪degrees × moles‬‬
‫‪force × length‬‬
‫‪energy‬‬
‫=‪R‬‬
‫=‬
‫‪degrees × moles‬‬
‫‪degrees × moles‬‬
‫=‪R‬‬
‫‪R = J K -1mol-1‬‬
‫‪R = Nm K -1mol-1‬‬
‫وﻓﯿﻤﺎ ﯾﻠﻲ ﺳﻨﺄﺧﺬ ﺑﻌﺾ ھﺬه اﻟﻘﯿﻢ اﻟﻌﺪدﯾﺔ ﻟﻠﺜﺎﺑﺖ ‪: R‬‬
‫‪ (١‬ﺍﳚﺎﺩ ﻗﻴﻤﺔ ﺍﻟﺜﺎﺑﺖ ﺍﳌﻮﻻﺭﻱ )‪ (R‬ﻟﻠﻐﺎﺯﺍﺕ ﺑﻮﺣﺪﺍﺕ ‪atm L /mol K‬‬
‫ﻣﻦ ﻗﺎﻧﻮن أﻓﻮﺟﺎدرو أن اﻟﻤﻮل اﻟﻮاﺣﺪ ﻣﻦ أي ﻏﺎز ﯾﺸﻐﻞ ﺣﺠﻤﺎً ﻗﺪره )‪ (22.414 L‬ﻋﻨﺪ‬
‫ﻣﻌﺪل اﻟﻀﻐﻂ ودرﺟﺔ اﻟﺤﺮارة )ﻋﻨﺪ اﻟﻈﺮوف اﻟﻘﯿﺎﺳﯿﺔ ‪(S.T.P = 273 K, 1 atm‬‬
‫وﺑﺎﻟﺘﻌﻮﯾﺾ ﻓﻲ اﻟﻌﻼﻗﺔ ‪:‬‬
‫‪P V 1 atm × 22.4136 L‬‬
‫=‬
‫‪n T 1 mol × 273.15 K‬‬
‫=‪R‬‬
‫‪⇒ R = 0.082056 atm.L/mol. K ≈ 0.0821 atm. L /mol K‬‬
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‫ ﻗﻮﺍﻧﲔ ﺍﻟﻐﺎﺯﺍﺕ‬: ‫ﺍﻟﻔﺼﻞ ﺍﻟﺜﺎﻧﻲ‬
‫ ﻋﻤﺮ ﺑﻦ ﻋﺒﺪ اﷲ اﻟﮭﺰازي‬/‫إﻋﺪاد د‬
: ‫( ﺗﺴﺎوي‬R) ‫( ﻟﻜﻦ ﻓﻲ ھﺬه اﻟﺤﺎﻟﺔ ﻓﺈن ﻗﯿﻤﺔ‬ml) ‫وﯾﻤﻜﻦ اﺳﺘﺨﺪام وﺣﺪة اﻟﺤﺠﻢ‬
0.0821 L.atm
0.0821 L × 103 ml L-1 .atm
R=
=
mol.K
mol . K
⇒ R = 82.1 ml.atm/mol.K
Fig. 62 :
a) Decreasing the volume of the gas at constant n and T increases the frequency of
collisions with the container walls and therefore increases the pressure (Boyle's law).
b) Increasing the temperature (kinetic energy) at constant n and P increases the volume of
the gas (Charles's law).
c) Increasing the amount of gas at constant T and P increases the volume (Avogadro's law).
d) Changing the identity of some molecules at constant T and V has no effect on the
pressure (Dalton's law).
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‫ ﻗﻮﺍﻧﲔ ﺍﻟﻐﺎﺯﺍﺕ‬: ‫ﺍﻟﻔﺼﻞ ﺍﻟﺜﺎﻧﻲ‬
‫ ﻋﻤﺮ ﺑﻦ ﻋﺒﺪ اﷲ اﻟﮭﺰازي‬/‫إﻋﺪاد د‬
Fig. 63 : Schematic illustrations of Boyle's law, Charles's law, and Avogadro's law
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‫ﺍﻟﻔﺼﻞ ﺍﻟﺜﺎﻧﻲ ‪ :‬ﻗﻮﺍﻧﲔ ﺍﻟﻐﺎﺯﺍﺕ‬
‫إﻋﺪاد د‪ /‬ﻋﻤﺮ ﺑﻦ ﻋﺒﺪ اﷲ اﻟﮭﺰازي‬
‫‪ (٢‬ﺇﳚﺎﺩ ﻗﻴﻤﺔ ﺍﻟﺜﺎﺑﺖ ﺍﳌﻮﻻﺭﻱ ﻟﻠﻐﺎﺯﺍﺕ )‪ (R‬ﺑﻮﺣﺪﺍﺕ ‪bar. L/mol K‬‬
‫ﻋﻨﺪ اﺳﺘﺨﺪام اﻟﺒﺎر ﻛﻮﺣﺪة ﻟﻠﻀﻐﻂ ﺑﺪﻻً ﻣﻦ ‪: atm‬‬
‫ﻓﺈن ‪: R‬‬
‫)‪( 1 atm = 1.01325 bar‬‬
‫‪PV‬‬
‫)‪(1.01325 bar) × (22.4136 L‬‬
‫=‬
‫‪nT‬‬
‫) ‪(1 mol ) × ( 273.15 K‬‬
‫=‪R‬‬
‫‪R = 0.08314 L bar/mol K‬‬
‫‪⇒ R = 0.08314 L bar/mol K‬‬
‫‪ (٣‬ﺇﳚﺎﺩ ﻗﻴﻤﺔ ﺍﻟﺜﺎﺑﺖ ﺍﳌﻮﻻﺭﻱ ﻟﻠﻐﺎﺯﺍﺕ )‪ (R‬ﺑﻮﺣﺪﺍﺕ ‪Pa . dm3/mol K‬‬
‫اﻟﻌﻼﻗﺔ ﺑﯿﻦ اﻟﺒﺎﺳﻜﺎل )‪ (Pa‬ﻛﻮﺣﺪة ﻟﻠﻀﻐﻂ اﻟﺠﻮي ووﺣﺪة )‪ (atm‬ھﻲ ‪:‬‬
‫)‪(1 atm = 101325 Pa‬‬
‫وﺑﺎﻟﺘﺎﻟﻲ ﻹﯾﺠﺎد ﻗﯿﻤﺔ )‪ (R‬ﺑﻮﺣﺪة ‪Pa . dm3/mol . K :‬‬
‫‪PV‬‬
‫‪nT‬‬
‫) ‪(101325 Pa) × (22.4136 dm 3‬‬
‫=‪R‬‬
‫‪1mol × 273.15 K‬‬
‫=‪R‬‬
‫‪⇒ R= 8314 Pa . dm 3/mol . K‬‬
‫‪⇒ R = 8.314 kPa . dm 3/mol . K‬‬
‫وﯾﻤﻜ ﻦ اﻟﺤ ﺼﻮل ﻋﻠ ﻰ ھ ﺬه اﻟﻘﯿﻤ ﺔ ﻣ ﻦ ﻣﻌﺮﻓ ﺔ ﻗﯿﻤ ﺔ ‪ R‬ﺑﻮﺣ ﺪة ‪(R = 8.314 atm :‬‬
‫‪L/mol K‬‬
‫وﻣﻦ ﻣﻌﺮﻓﺔ اﻟﻌﻼﻗﺔ ﺑﯿﻦ ‪:‬‬
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‫ ﻗﻮﺍﻧﲔ ﺍﻟﻐﺎﺯﺍﺕ‬: ‫ﺍﻟﻔﺼﻞ ﺍﻟﺜﺎﻧﻲ‬
‫ ﻋﻤﺮ ﺑﻦ ﻋﺒﺪ اﷲ اﻟﮭﺰازي‬/‫إﻋﺪاد د‬
1 atm = 101325 Pa
1 L = 1 dm3
0.082056 atm . L × 101325 Pa/atm . dm 3 /L )
(
0.08206 atm. L
R=
=
mol.K
mol . K
3
R = 8314.32 Pa dm / mol K
R = 8.314 kPa dm3 / mol K
Pa . m3/mol K ‫( ﺑﻮﺣﺪﺍﺕ‬R) ‫( ﺇﳚﺎﺩ ﻗﻴﻤﺔ ﺍﻟﺜﺎﺑﺖ ﺍﳌﻮﻻﺭﻱ ﻟﻠﻐﺎﺯﺍﺕ‬٤
PV
nT
(101325 Pa) × (0.0224136 m3 )
R=
1mol × 273.15 K
R = 8.314 Pa. m 3 /mol .K
R=
⇒ R = 8.314 Pa . m 3 / mol K
: ‫ﻣﻠﺤﻮﻇﺔ‬
: ‫( ﺣﯿﺚ أن‬Joul) ‫( اﻟﻰ وﺣﺪة‬Pa . m3) ‫وﯾﻤﻜﻦ ﺗﺤﻮﯾﻞ وﺣﺪة‬
1 Pa m 3 = 1 J
R = 8.314 Pa . m 3 /mol . K
⇒ R = 8.314 J/ mol K
⇒ R = 8.314 J/ mol K
dyne. cm /mol K ‫( ﺑﻮﺣﺪﺍﺕ‬R) ‫( ﺇﳚﺎﺩ ﻗﻴﻤﺔ ﺍﻟﺜﺎﺑﺖ ﺍﳌﻮﻻﺭﻱ ﻟﻠﻐﺎﺯﺍﺕ‬٥
‫( )ﺣﯿﺚ‬1 atm) ‫ وھﻲ ﺗﺮادف ﺿﻐﻄﺎً ﻗﺪره واﺣﺪ ﺟﻮ‬dyne/cm2 ‫ھﻨﺎك وﺣﺪة ﺗﺴﻤﻰ‬
1 dyne = 1 g . cm . s-2 : ‫اﻟﺪاﯾﻦ وﺣﺪة ﻟﻠﻘﻮة وھﻲ ﺗﺴﺎوي‬
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‫ﺍﻟﻔﺼﻞ ﺍﻟﺜﺎﻧﻲ ‪ :‬ﻗﻮﺍﻧﲔ ﺍﻟﻐﺎﺯﺍﺕ‬
‫إﻋﺪاد د‪ /‬ﻋﻤﺮ ﺑﻦ ﻋﺒﺪ اﷲ اﻟﮭﺰازي‬
‫وﻟﺘﺤﻮﯾﻞ وﺣﺪة اﻟﻀﻐﻂ اﻟﺠﻮي )‪) (1 atm‬واﻟﺘﻲ ﺗﻜﺎﻓﻲء ﻋﻤﻮداً ﻣﻦ اﻟﺰﺋﺒﻖ ﻃﻮﻟﮫ ‪(76‬‬
‫)‪ cm‬اﻟﻰ وﺣﺪة ‪ dyne/cm2‬ﻧﺴﺘﺨﺪم ﻧﻔﺲ اﻟﻌﻼﻗﺔ اﻟﺴﺎﺑﻘﺔ ‪:‬‬
‫‪P=hdg‬‬
‫‪g‬‬
‫‪cm‬‬
‫)‬
‫×‬
‫‪(980.6667‬‬
‫)‬
‫‪cm3‬‬
‫‪s2‬‬
‫)‪( d‬‬
‫)‪( a‬‬
‫‪1atm = (76.00 cm) × (13.5951‬‬
‫‪1 atm = 1013251.9 g cm-1 s-2‬‬
‫‪10132252 g cm s-2‬‬
‫= ‪1 atm‬‬
‫‪= 1013252 dyne/cm2‬‬
‫‪2‬‬
‫‪cm‬‬
‫‪1 atm = 1.013252 × 106 dyne/cm2‬‬
‫وھ ﺬه اﻟﻘﯿﻤ ﺔ ﻟﻠ ﻀﻐﻂ ﺗﻌ ﺎدل‬
‫)‪ (1 atm‬وﺑﺎﻟﺘ ﺎﻟﻲ ﻟﺘﺤﻮﯾ ﻞ اﻟ ﻀﻐﻂ اﻟ ﻰ وﺣ ﺪات‬
‫‪: dyne. cm/mol K‬‬
‫) ‪P( dyne/cm 2 ) × (cm3‬‬
‫‪= N . m mol-1 K -1‬‬
‫‪mol K‬‬
‫) ‪(1.013252 × 106 dyne/cm 2 ) × (22413.6 cm3‬‬
‫=‪R‬‬
‫‪1 mol × 273.15 K‬‬
‫‪R = 83143419.47 dyne . cm/ mol K‬‬
‫=‪R‬‬
‫‪⇒ R = 8.314 × 107 dyne . cm/ mol K‬‬
‫‪ (٦‬ﺇﳚﺎﺩ ﻗﻴﻤﺔ ﺍﻟﺜﺎﺑﺖ ﺍﳌﻮﻻﺭﻱ ﻟﻠﻐﺎﺯﺍﺕ )‪ (R‬ﺑﻮﺣﺪﺓ ﺍﻹﺭﺝ ‪erg/mol K‬‬
‫اﻹرج ﻋﺒﺎرة ﻋﻦ اﻟﺸﻐﻞ اﻟﻤﺒﺬول ﻋﻨﺪﻣﺎ ﺗﺆﺛﺮ ﻗﻮة ﻗﺪرھﺎ واﺣﺪ داﯾﻦ)‪ (1 dyne‬ﻋﻠﻰ ﻣﺴﺎﻓﺔ‬
‫ﻗﺪرھﺎ )‪ (1 cm‬وھﻮ ﻣﻦ وﺣﺪات اﻟﻄﺎﻗﺔ‪ .‬وﺑﺎﻟﺘﺎﻟﻲ ﻓﺈن ‪:‬‬
‫‪1 erg = 1 dyne. cm‬‬
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‫ﺍﻟﻔﺼﻞ ﺍﻟﺜﺎﻧﻲ ‪ :‬ﻗﻮﺍﻧﲔ ﺍﻟﻐﺎﺯﺍﺕ‬
‫إﻋﺪاد د‪ /‬ﻋﻤﺮ ﺑﻦ ﻋﺒﺪ اﷲ اﻟﮭﺰازي‬
‫ﻭﳊﺴﺎﺏ ﻗﻴﻤﺔ ‪ R‬ﺑﻮﺣﺪﺓ ‪:erg‬‬
‫) ‪PV (1.013252 × 106 dyne/cm2 ) × (22413.6 cm3‬‬
‫=‪R‬‬
‫=‬
‫‪RT‬‬
‫)‪(1 mol) × (273.15 K‬‬
‫‪R = 83143419.47 dyne. cm/mol.K‬‬
‫‪R = 83143419.47 erg/mol.K‬‬
‫‪⇒ R = 8.31 × 10 7 erg/mol.K‬‬
‫وﻧﻈﺮاً ﻷن اﻹرج ﻛﻤﯿﺔ ﺻﻐﯿﺮة ﻣﻦ اﻟﻄﺎﻗﺔ‪ ،‬ﻓﺈﻧﮫ ﯾﻌﺒﺮ ﺑﻮﺣﺪة أﻛﺜﺮ ﻣﻼءﻣﺔ وھﻲ اﻟﺠﻮل‬
‫ﺣﯿﺚ أن ‪:‬‬
‫‪1 Joul = 107 erg‬‬
‫‪⇒ R = 8.314 × 107 erg/mol.K‬‬
‫‪R = 8.314 Joul/K.mol‬‬
‫‪ (٧‬ﺇﳚﺎﺩ ﻗﻴﻤﺔ ﺍﻟﺜﺎﺑﺖ ﺍﳌﻮﻻﺭﻱ ﻟﻠﻐﺎﺯﺍﺕ )‪ (R‬ﺑﻮﺣﺪﺍﺕ ‪N .m /mol K‬‬
‫ﻓﻲ ھﺬه اﻟﺤﺎﻟﺔ ﺳﻨﺴﺘﺨﺪم وﺣﺪة اﻟﻀﻐﻂ )‪ (N/m2‬ووﺣﺪة اﻟﺤﺠﻢ )‪ (m3‬أي ﺗﻜﻮن وﺣﺪة ‪: R‬‬
‫) ‪P(N/m 2 ) × (m 3‬‬
‫=‪R‬‬
‫‪= N . m mol -1K -1‬‬
‫‪mol K‬‬
‫ﺗﻌﺮﻳﻒ ﺍﻟﻨﻴﻮﺗﻦ ‪:‬‬
‫وھﻮ اﻟﻘﻮة اﻟﺘﻲ ﺗﻜﺴﺐ ﻛﺘﻠﺔ ﻗﺪرھﺎ ) ‪ (1 Kg‬إﺳﺮاﻋﺎً ﻗﺪره )‪.(1 m/s2‬‬
‫واﻟﻨﯿﻮﺗﻦ )‪ (N‬وﺣﺪة اﻟﻘﻮة ﻓﻲ ﻧﻈﺎم )‪(m . Kg . s‬‬
‫وﻟﻠﺘﻌﺒﯿﺮ ﻋﻦ اﻟﻀﻐﻂ اﻟﺠﻮي اﻟﻘﯿﺎﺳﻲ )‪ (Standard Atmosphere‬ﺑﻮﺣﺪات‬
‫)‪:(m . Kg .s‬‬
‫)‪(163‬‬
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‫ ﻗﻮﺍﻧﲔ ﺍﻟﻐﺎﺯﺍﺕ‬: ‫ﺍﻟﻔﺼﻞ ﺍﻟﺜﺎﻧﻲ‬
‫ ﻋﻤﺮ ﺑﻦ ﻋﺒﺪ اﷲ اﻟﮭﺰازي‬/‫إﻋﺪاد د‬
‫ﻧﻀﺮب ﻛﺘﻠﺔ اﻟﺰﺋﺒﻖ )ﺑﻮﺣﺪة اﻟﻜﯿﻠﻮ ﺟﺮام( اﻟﺬي ﯾﺆﺛﺮ ﻋﻠﻰ اﻟﻤﺘﺮ اﻟﻤﺮﺑﻊ ﺑﻌﺠﻠﺔ اﻟﺠﺎذﺑﯿﺔ‬
: ‫اﻷرﺿﯿﺔ‬
P=h.d.g
P = h (m) . d (Kg/m 3 ) . g (m/s 2 ) = Kg m -1 s -2 = Kg m s -2 /m 2 = N/m 2



Newton
‫( ﻓﺈن ھﺬه‬h = 76 cm, d = 13.596 g/cm3, g = 980.7 cm/s2) ‫ﻓﺈذا ﻋﻠﻤﻨﺎ أن‬
: ‫( ﻛﻤﺎ ﯾﻠﻲ‬Kg, m) ‫اﻟﻮﺣﺪات ﯾﺠﺐ ﺗﺤﻮﯾﻠﮭﺎ إﻟﻰ‬
h Hg = 76.00 cm = 0.7600 m
13.5951 g 13.5951 g × 10-3 Kg g -1
=
= 13595.1 Kg m-3
3
3
-6
3
-3
cm
1 cm × 10 m cm
980.6665 cm
980.6665 cm × 10-2 m cm -1
g=
=
= 9.806665 ms-2
2
2
s
s
-3
-2
P = h (m) . d (kg m ) . g (ms )
d Hg =
P = (0.7600 m) × (13595.1 kg m- 3 ) × (9.806665 m s- 2 )
P = 101325.1694 kg m-1 s-2 = 1.01325 × 105 kg m-1s-2
P = 1.01325 × 105 Kg m s-2 /m2



(where N = Kg m s-2 )
N
P = 1.01325 × 10 N/m 2
5
N. m/mol ‫( وﺑﺎﻟﺘ ﺎﻟﻲ ﻟﺘﺤﻮﯾ ﻞ اﻟ ﻀﻐﻂ اﻟ ﻰ وﺣ ﺪات‬1 atm) ‫وھﺬه اﻟﻘﯿﻤﺔ ﻟﻠﻀﻐﻂ ﺗﻌﺎدل‬
:K
P (N/m2 ) × (m3 )
= N . m mol-1 K-1
mol K
(1.01325 × 105 N/m2 ) × (0.0224136 m3 )
R=
1 mol × 273.15 K
R=
⇒ R = 8.314 N . m/ mol K
(164)
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‫)‪(165‬‬
‫ﺍﻟﻔﺼﻞ ﺍﻟﺜﺎﻧﻲ ‪ :‬ﻗﻮﺍﻧﲔ ﺍﻟﻐﺎﺯﺍﺕ‬
‫إﻋﺪاد د‪ /‬ﻋﻤﺮ ﺑﻦ ﻋﺒﺪ اﷲ اﻟﮭﺰازي‬
‫‪ (٨‬ﺇﳚﺎﺩ ﻗﻴﻤﺔ ﺍﻟﺜﺎﺑﺖ ﺍﳌﻮﻻﺭﻱ ﻟﻠﻐﺎﺯﺍﺕ )‪ (R‬ﺑﻮﺣﺪﺍﺕ ‪J/mol K‬‬
‫أوﺟﺪﻧﺎ ﻓﻲ اﻟﻔﻘﺮة اﻟﺴﺎﺑﻘﺔ ﻗﯿﻤﺔ اﻟﺜﺎﺑﺖ )‪. (R = 8.314 N. m/mol K‬‬
‫ﻭﺍﳉﻮﻝ ھﻮ ﻗﻮة ﻗﺪرھﺎ ﻧﯿﻮﺗﻦ ﻣﻀﺮوﺑﺔ ﻓﻲ ﻣﺴﺎﻓﺔ ﻗﺪرھﺎ )‪:(1 m‬‬
‫‪1 Joule = N . m‬‬
‫وﺑﺎﻟﺘﺎﻟﻲ ﻓﺈن ‪:‬‬
‫‪J = N. m‬‬
‫‪ R = 8.314 N. m/mol K‬‬
‫‪⇒ R = 8.314 J/mol. K‬‬
‫وﺑﺎﻟﺘ ﺎﻟﻲ ﻋﻨ ﺪ اﻟﺘﻄﺒﯿ ﻖ ﻓ ﻲ ﻣﻌﺎدﻟ ﺔ اﻟﻐ ﺎز اﻟﻤﺜ ﺎﻟﻲ ﺑﻘﯿﻤ ﺔ )‪ (8.314 J/mol K‬ﻓﯿﺠ ﺐ أن‬
‫ﻧﺴﺘﺨﺪم ﻟﻠﻀﻐﻂ وﺣﺪة ﺑﺎﺳﻜﺎل )‪ (Pa‬وﻟﻠﺤﺠﻢ وﺣﺪة ﻣﺘﺮ ﻣﻜﻌﺐ )‪.(m3‬‬
‫‪ (٩‬ﺇﳚﺎﺩ ﻗﻴﻤﺔ ﺍﻟﺜﺎﺑﺖ ﺍﳌﻮﻻﺭﻱ ﻟﻠﻐﺎﺯﺍﺕ )‪ (R‬ﺑﻮﺣﺪﺍﺕ ﺍﻟﺴﻌﺮ ‪Cal/mol K‬‬
‫ﻏﺎﻟﺒﺎً ﻣﺎ ﺗﺴﺘﻌﻤﻞ ﻓﻲ ﻣﺴﺎﺋﻞ اﻟﻜﯿﻤﯿﺎء اﻟﺤﺮارﯾﺔ واﻟﺪﯾﻨﺎﻣﯿﻜﺎ اﻟﺤﺮارﯾﺔ وﺣﺪة ﻟﻠﻄﺎﻗﺔ ﺗﻌﺮف‬
‫ﺑﺎﻟﺴﻌﺮ )‪ (calorie‬ﺣﯿﺚ أن اﻟﻌﻼﻗﺔ ﺑﯿﻦ اﻟﺴﻌﺮ واﻟﺠﻮل‪:‬‬
‫‪1 Cal. = 4.184 J‬‬
‫وﺑﺎﻟﺘﺎﻟﻲ ﻹﯾﺠﺎد ﻗﯿﻤﺔ ‪ R‬ﺑﻮﺣﺪة اﻟﺴﻌﺮ ﻓﺈن ‪:‬‬
‫‪8.314 J / mol K‬‬
‫‪4.184 J / Cal‬‬
‫=‪R‬‬
‫‪⇒ R = 1.987 C al/K m ol ≈ 2 C al/m ol K‬‬
‫)‪(165‬‬
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(166)
‫ ﻗﻮﺍﻧﲔ ﺍﻟﻐﺎﺯﺍﺕ‬: ‫ﺍﻟﻔﺼﻞ ﺍﻟﺜﺎﻧﻲ‬
‫ ﻋﻤﺮ ﺑﻦ ﻋﺒﺪ اﷲ اﻟﮭﺰازي‬/‫إﻋﺪاد د‬
‫ﺍﻟﻌﻼﻗﺔ ﺑﲔ ﺍﻟﻨﻴﻮﺗﻦ ﻭﺍﻟﺪﺍﻳﻦ‬
1 dyne = 10-5 N
:(1 m) ‫واﻟﺠﻮل ھﻮ ﻗﻮة ﻗﺪرھﺎ ﻧﯿﻮﺗﻦ ﻣﻀﺮوﺑﺔ ﻓﻲ ﻣﺴﺎﻓﺔ ﻗﺪرھﺎ‬
1 Joule = N . m
N/m2 ‫ اﻟﻰ‬dyne/cm2 ‫وﻟﺘﺤﻮﯾﻞ وﺣﺪة اﻟﻀﻐﻂ ﻣﻦ‬
1dyne 1 × 10-5 N
2
P=
=
=
0.1
N/m
cm 2 1 × 10-4 m 2
⇒ P = 1dyne/cm2 = 0.1 N/m2
: ‫وﺑﻤﺎ أن‬
1atm = 1.013 × 106 dyne/cm2
⇒ 1dyne/cm2 = 0.1N/m2
1dyne/cm2 = 0.1 N/m2
⇒ 1.013 × 106 dyne/cm2 = P
0.1N/m2 × 1.013 × 106 dyne/cm2
= 1.013 × 105 N/m2
P=
2
1dyne/cm
(1 J = 1 N. ‫ ( ﺣﯿﺚ‬J/K.mol ) ‫ أو‬N.m/K.mol ‫ ﺑﻮﺣﺪة‬R ‫وﺑﺎﻟﺘﺎﻟﻲ ﻟﺤﺴﺎب ﻗﯿﻤﺔ‬
m)
R=
R=
PV
nT
(1.013 × 105 Newton m-2 ) × ( 0.0224136 m3 )
(1 mol) × (273.15 K)
⇒ R = 8.314 J/K.mol
(166)
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(167)
‫ ﻗﻮﺍﻧﲔ ﺍﻟﻐﺎﺯﺍﺕ‬: ‫ﺍﻟﻔﺼﻞ ﺍﻟﺜﺎﻧﻲ‬
‫ ﻋﻤﺮ ﺑﻦ ﻋﺒﺪ اﷲ اﻟﮭﺰازي‬/‫إﻋﺪاد د‬
: k ‫ﺛﺎﺑﺖ ﺑﻮﻟﺘﺰﻣﺎﻥ‬
‫( وھﻮ ﻋﺒﺎرة ﻋﻦ ﺛﺎﺑﺖ اﻟﻐﺎز ﻟﻜﻞ ﺟﺰيء‬Boltzmann constant) (k) ‫ﺛﺎﺑﺖ ﺑﻮﻟﺘﺰﻣﺎن‬
(Gas Constant per Molecule)
R
8.314 × 107 erg K -1 mol-1
k=
=
= 1.380 × 10-16 erg / K. molecule
23
-1
NA
6.023 × 10 molecules . mol
k=
R
8.314 J K -1 mol-1
=
= 1.380 × 10-23 J / K . molecule
23
-1
NA
6.023 × 10 molecules . mol
‫ وﻓﻘﺎً ﻟﻮﺣﺪات اﻟﻀﻐﻂ واﻟﺤﺠﻢ‬R ‫ ﻣﻠﺨﺺ ﻟﺒﻌﺾ ﻗﯿﻢ اﻟﺜﺎﺑﺖ‬:١٥ ‫ﺟﺪول‬
‫اﻟﻘﯿﻤﺔ اﻟﻌﺪدﯾﺔ‬
R ‫ﻟـ‬
0.082056
82.056
0.08314
8.314
8.314
8.314
8.314
8.314 x 107
8.314 x 107
1.987
‫وﺣﺪة‬
R
atm L / mol K
atm ml / mol K
bar L / mol K
KPa. dm3/mol K
Pa. m3 / mol K
N. m / mol K
J / mol K
dyne. cm/mol K
erg / mol K
cal / mol K
‫وﺣﺪة‬
‫اﻟﻀﻐﻂ‬
atm
atm
bar
kPa
Pa
N/m2
Pa
dyne/cm2
dyne/cm2
‫وﺣﺪة‬
‫اﻟﺤﺠﻢ‬
L
ml
L
dm3
m3
m3
m3
cm3
cm3
(٥١) ‫ﻣﺜﺎﻝ‬
‫ ﻋﻨﺪ درﺟﺔ‬4.20 g ‫ ﻣﻘﺪارھﺎ‬F2(g) ‫اﺣﺴﺐ ﺣﺠﻢ اﻟﻐﺎز اﻟﺬي ﺗﺸﻐﻠﮫ ﻛﻤﯿﺔ ﻣﻦ ﻏﺎز اﻟﻔﻠﻮر‬
.(F = 19) : ‫ )ﻋﻠﻤﺎً ﺑﺄن اﻟﻜﺘﻠﺔ اﻟﺬرﯾﺔ‬720 torr ‫ وﺗﺤﺖ ﺿﻐﻂ‬42 °C
(167)
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