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Mutemo waHess: Kukosha kweMutemo weKuchengetedza Simba muKuita kweMakemikoro
Pengantar
Chemistry haisi kungochinja mavara, maumbirwo, uye maitiro anoshamisa mumachubhu ekuyedza. Seri kwemaitiro ese emakemikari kune misimboti mikuru inodzora maitiro ezvinhu nesimba. Imwe yemisimboti iyi iMutemo waHess, uyo unoita basa rakakosha mukunzwisisa kuti simba rinobatanidzwa uye rinotamiswa sei panguva yemaitiro emakemikari.
Tsanangudzo yeMutemo waHess
Mutemo waHess, wakatumidzwa zita remunyanzvi wemakemikari wekuRussia Germain Henri Hess, ndeimwe yenheyo huru dzethermochemistry. Mutemo uyu unoti shanduko yese ye enthalpy panguva yekuita kwemakemikari yakafanana, zvisinei nenzira kana matanho anotorwa. Nemamwe mashoko, kana kuita kwekutanga uye zvigadzirwa zvekupedzisira zvikaramba zvakafanana, saka huwandu hwese hwesimba hunodiwa kana kuburitswa hucharamba hwakafanana.
Panyaya yemasvomhu, Mutemo waHess unogona kutsanangurwa seizvi:
\[ \Delta H_{total} = \Delta H_1 + \Delta H_2 + \Delta H_3 + \ldots + \Delta H_n \]
Apo \(\Delta H\) pane shanduko ye enthalpy padanho rega rega rekuita.
Nheyo huru dzeMutemo waHess
Mutemo waHess chaizvoizvo kushandiswa kwemutemo wekuchengetedza simba kukemikari. Zvinoenderana nemutemo wekuchengetedza simba, simba harigone kugadzirwa kana kuparadzwa—rinogona kungochinja kubva pane chimwe chimiro kuenda kune chimwe. Mumamiriro ekuita kwemakemikari, simba iri rinowanzo ratidzwa muchimiro che enthalpy (H), iyo inoyera simba rese rakachengetwa muhurongwa.
Kana maitiro emakemikari akagona kurongwazve kuita matanho madiki akasiyana nemaitiro akananga, saka tinogona kusanganisa shanduko dze enthalpy dzematanho madiki ese aya kuti tiwane shanduko yakazara ye enthalpy. Izvi zvinoreva kuti tinogona kuverenga huwandu hwe enthalpy yemaitiro akaomarara nekubvisa enthalpies dzemaitiro ari nyore anoiumba.
Kushandiswa kweMutemo waHess
Mutemo waHess une mashandisirwo akawanda anoshanda muzvikamu zvakasiyana-siyana zvekemikari, zvimwe zvacho zvinosanganisira:
1. Kuverengwa kweReaction Enthalpy
Patinosangana nemhinduro iyo zvakaoma kuyera zvakananga shanduko ye enthalpy, Mutemo waHess unotibvumira kupatsanura mhinduro yacho kuita matanho ari nyore, ayo shanduko dze enthalpy dzinogona kuyerwa zviri nyore kana kuzivikanwa kubva ku data riripo re thermochemical.
Muenzaniso: Ngatitii tinoda kuona shanduko ye enthalpy (\(\Delta H\)) yemhinduro:
\[ C(s) + 1/2 \, O_2(g) \museve wekurudyi CO(g) \]
Tinogona kupatsanura maitiro aya kuita seizvi:
\[ C(s) + O_2(g) \museve wekurudyi CO_2(g) \quad (\Delta H = -393.5 \; \text{kJ/mol}) \]
\[ CO_2(g) \museve wekurudyi CO(g) + 1/2 \, O_2(g) \quad (\Delta H = +283.0 \; \text{kJ/mol}) \]
Uchishandisa Mutemo waHess, shanduko yese ye enthalpy ndeiyi:
\[ \Delta H = -393.5 \; \zvinyorwa{kJ/mol} + 283.0 \; \chinyorwa{kJ/mol} = -110.5 \; \zvinyorwa{kJ/mol} \]
2. Kugadzwa kweBond Energy
Mutemo waHess unowanzo shandiswawo kuona simba remabhondi risingakwanise kuyerwa zvakananga. Nekushandisa data re enthalpy kubva mumaitiro anozivikanwa uye fungidziro dzakasiyana-siyana kana dzimwe nzira dzekuenzanisa, masayendisiti anogona kufungidzira simba rinobatanidzwa mukuputsa nekugadzira mabhondi emakemikari.
3. Kudzidza kweThermodynamics yeMhinduro
Mumishonga uye kemesitiri yekuongorora, Hess's Law inobatsira kunzwisisa kunyungudika (kunyungudika) uye kuunganidzwa (kusunga) kwezvinhu. Semuenzaniso, inobatsira kusiyanisa entropy (ΔS) ne enthalpy (ΔH) yemushonga unonyungudika muzvinhu zvakasiyana-siyana zvinonyungudika.
Nhoroondo neKubudirira
Mutemo waHess wakatanga kuumbwa naGermain Henri Hess muna 1840. Panguva iyoyo, Hess akaona kuti kupisa kunoburitswa kana kunyudzwa mukuita kwemakemikari pakumanikidzwa nguva dzose kwakafanana, zvisinei nekuti kuita kwacho kunoitika zvakananga here kana kuti kuburikidza nematanho akatevedzana.
Kuwanikwa kwake kwakagadzira nzira yekufambira mberi mukudzidza kwethermochemistry, kusanganisira dzimwe pfungwa dzakakosha dzakadai semabasa ehurumende, uko huwandu hwacho husingatsamiri pakuti hurongwa hwasvika sei mumamiriro iwayo asi chete pamamiriro ekutanga neekupedzisira.
Muenzaniso weNhamba weKushandisa Mutemo waHess
Semuenzaniso chaiwo wekushandiswa kweMutemo waHess, tichaverenga shanduko ye enthalpy kubva pakupiswa kwemethane kuenda ku carbon dioxide nemvura:
\[ CH_4(g) + 2 \, O_2(g) \museve wekurudyi CO_2(g) + 2 \, H_2O(g) \]
Matanho acho ndeanotevera:
1. Kupiswa kwemethane kuita kabhoni dhayokisaidhi nemvura:
\[ CH_4(g) + 2 \, O_2(g) \museve wekurudyi CO_2(g) + 2 \, H_2O(g) \quad (\Delta H_{reaction?}) \]
2. Tinoziva:
\[ CH_4(g) + 2 \, O_2(g) \museve wekurudyi CO_2(g) + 2 \, H_2O(l) \quad (\Delta H = -890.3 \; \text{kJ/mol}) \]
Zvadaro:
\[ H_2O(l) \museve wekurudyi H_2O(g) \quad (\Delta H_{vap} = +44.0 \; \text{kJ/mol}) \]
Kushandisa Mutemo waHess:
\[ \Delta H = -890.3 \; \text{kJ/mol} + 2 \cdot 44.0 \; \text{kJ/mol} = -802.3 \; \text{kJ/mol} \]
Saka, shanduko ye enthalpy yekupiswa kwe methane kuita carbon dioxide nemvura pasi pemamiriro akasiyana ekuita zvinogona kuverengerwa zviri nyore uchishandisa Hess's Law.
Mhedziso
Mutemo waHess unopa ruzivo rwakadzama pamusoro pekuchengetedzwa kwesimba mukuita kwemakemikari uye unobatsira masayendisiti emakemikari nevashandi vezvemakemikari kunzwisisa nekufanotaura maitiro e thermochemical ekuita kwakasiyana-siyana. Nerubatsiro rwemisimboti yeMutemo waHess, kushandurwa kwesimba kunoitika padanho re microscopic kunogona kuverengwa nekuongororwa nemazvo, zvichigonesa kufambira mberi mune mamwe mapazi akasiyana ekemikari, fizikisi, uye tekinoroji yezvinhu.
Nekunzwisisa kwakanaka kweMutemo waHess, kwete masayendisiti emakemikari chete, asiwo vaongorori vanobva kumatunhu akasiyana-siyana vanogona kuongorora nekugadzirisa maitiro emakemikari ekushandisa zvakasiyana-siyana, kubva pakugadzira makemikari kusvika pakugadzira tekinoroji yesimba.
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Chinyorwa chino chinopfupikisa tsananguro, misimboti yekutanga, mashandisirwo anoitwa zvinhu, nhoroondo, uye mienzaniso chaiyo yeMutemo waHess muthermochemistry. Tinovimba kuti izvi zvichakubatsira kunzwisisa nekushandisa pfungwa iyi inokosha mukemistri.
