Ka Hoʻololi ʻana o ka Enthalpy ma ke Kūlana Maʻamau
He manaʻo nui ka Enthalpy i ka thermodynamics e kōkua iā mākou e hoʻomaopopo pehea e hoʻoili ʻia ai ka ikehu i nā hopena kemika a me nā kaʻina hana kino. Ma ke ʻano maʻamau, ʻo ka enthalpy (H) ka huina o ka ikehu kūloko o kahi ʻōnaehana a me ka huahana o ke kaomi (P) a me ka nui (V) o kēlā ʻōnaehana. Ma nā huaʻōlelo makemakika, ua hōʻike ʻia ka enthalpy ma ke ʻano he H = U + PV, kahi ʻo U ka ikehu kūloko o ka ʻōnaehana.
Ma ke ʻano o ka kemika, ʻo ka loli enthalpy (\(\Delta H\)) ka ʻokoʻa o ka enthalpy ma waena o nā huahana a me nā reactants i loko o kahi hopena kemika. Ke nānā mākou i nā hopena kemika i loko o ka hale hana a i ʻole ma ke ʻano, makemake pinepine mākou i ke ana ʻana a me ka hoʻomaopopo ʻana pehea e loli ai ka enthalpy i ka wā o ka hopena.
Kūlana Maʻamau
Hoʻohana ʻia nā kūlana maʻamau ma ke ʻano he kuhikuhi a i ʻole kahi hoʻomaka no nā ana enthalpy, e ʻae ana iā mākou e hoʻohālikelike maʻalahi i nā hopena a me nā kūlana like ʻole. Hoʻākāka pinepine ʻia nā kūlana maʻamau i ka kemika penei:
1. Kaomi: 1 lewa (atm) a i ʻole 1 bar.
2. Mahana: ʻO ka maʻamau he 298,15 K (25°C), ʻoiai hiki ke loli nā mahana maʻamau ma muli o ka pōʻaiapili.
3. Ka nui o ka hui ʻana: 1 M no ka hopena.
4. Kūlana kino: ʻo ke kūlana kino maʻamau ke kahua paʻa loa o kahi mea ma kēlā mahana a me ke kaomi.
Ke kūkākūkā mākou i ka "loli enthalpy ma lalo o nā kūlana maʻamau," ke kuhikuhi pinepine nei mākou i ka loli enthalpy o kahi hopena kemika e hana nei ma lalo o kēlā mau kūlana maʻamau.
Nā ʻAno o nā Hoʻololi Enthalpy
Aia kekahi mau ʻano loli enthalpy i ʻike pinepine ʻia i ka kemika, e hōʻike ana kēlā me kēia i nā kaʻina hana kino a kemika like ʻole.
1. Enthalpy o ka Hoʻokumu ʻana (ΔHf°): ʻO kēia ka loli enthalpy ke hoʻokumu ʻia hoʻokahi mole o kahi hui mai kona mau mea ma lalo o nā kūlana maʻamau. No ka laʻana, inā mākou e hoʻokumu i ka wai (H2O) mai ke kinoea hydrogen (H2) a me ke kinoea oxygen (O2) ma lalo o nā kūlana maʻamau, ʻo ka loli enthalpy pili ka enthalpy maʻamau o ka hoʻokumu ʻana o ka wai.
\[ 2H_2 (g) + O_2 (g) \arrow 2H_2O (l) \]
E ana ʻia ka loli enthalpy no kēia hopena ma ke ʻano he ΔHf°.
2. Enthalpy o ke kuni ʻana (ΔHc°): ʻO kēia ka loli enthalpy ke puhi piha ʻia kekahi mole o kahi mea i ka oxygen ma lalo o nā kūlana maʻamau. No ka laʻana, ke kuni ʻana o ka methane (CH4) i ka oxygen:
\[ CH_4 (g) + 2O_2 (g) \arrow CO_2 (g) + 2H_2O (l) \]
ʻO ka loli enthalpy no kēia hopena ʻo ia ka enthalpy maʻamau o ke kuni ʻana o ka methane.
3. Enthalpy o ka Dissociation (ΔHd°): ʻO kēia ka loli enthalpy e pono ai e uhaʻi i hoʻokahi mole o kahi pilina kikoʻī i loko o kahi mole kinoea ma lalo o nā kūlana maʻamau. No ka laʻana, ka dissociation o nā mole chlorine (Cl2) i loko o nā ʻātoma chlorine:
\[ Cl_2 (g) \rightarrow 2Cl (g) \]
ʻO ka enthalpy i ana ʻia ʻo ia ka enthalpy dissociation maʻamau no ka pilina Cl-Cl.
4. Enthalpy o ka Vaporization (ΔHvap°): ʻO kēia ka loli enthalpy ke hoʻoheheʻe ʻia kekahi mole o ka wai i loko o ke kinoea ma lalo o nā kūlana maʻamau.
\[ H_2O (l) \arrow H_2O (g) \]
He mea nui kēia loli i ka hanana o ka loli pae.
Ke Kumumanaʻo o Hess
ʻO kekahi o nā kānāwai pono loa i ka thermodynamics kemika ʻo ia ke Kānāwai o Hess. Ke ʻōlelo nei kēia kānāwai ua like ka loli enthalpy o kahi hopena holoʻokoʻa me ka huina algebraic o nā loli enthalpy o nā ʻanuʻu hopena liʻiliʻi. I nā huaʻōlelo ʻē aʻe, ʻo ka loli enthalpy kahi waiwai o ke kūlana—pili wale ia i nā kūlana mua a me ka hope, ʻaʻole ma ke ala i lawe ʻia.
Eia kekahi laʻana, inā ʻaʻole hiki iā mākou ke ana pololei i ka loli enthalpy o kahi hopena akā ʻike i nā enthalpies o kekahi mau hopena pili, hiki iā mākou ke hoʻohana i ke Kānāwai o Hess e helu i ka loli enthalpy.
Ana o ka Hoʻololi Enthalpy
Hana pinepine ʻia ke ana pololei ʻana o ka loli enthalpy o kahi hopena me ka hoʻohana ʻana i kahi calorimeter. ʻO ka Calorimetry kahi ʻano hoʻokolohua e ana i ka wela i hoʻokuʻu ʻia a i ʻole i omo ʻia e kahi ʻōnaehana. ʻO nā ʻano calorimeter i hoʻohana pinepine ʻia:
1. Kalolomika pōkā: Hoʻohana ʻia kēia e ana i ka loli enthalpy o ke kuni ʻana. Hoʻokomo ʻia ka hāpana i loko o kahi pahu pani i kapa ʻia he pōkā a puhi ʻia i loko o kahi lewa oxygen maʻemaʻe. Ana ʻia ka wela i hoʻokuʻu ʻia i ka wā o ke kuni ʻana e hoʻoholo ai i ka ΔHc°.
2. Calorimeter Solution: Hoʻohana ʻia ke hana ʻia kahi hopena i loko o kahi hopena, kahi i hoʻokuʻu ʻia ai a omo ʻia paha ka wela e hoʻololi ai i ka mahana i loko o ka hopena. Hiki ke pili ke ana ʻana o ka loli o ka mahana i ka loli enthalpy me ka hoʻohana ʻana i ka mana wela kikoʻī o ka hopena.
Nā Hoʻohana i ke Ola o kēlā me kēia Lā
He nui nā hoʻohana pono o nā loli enthalpy. ʻO kekahi mau laʻana:
1. ʻOihana Ikehu: He mea nui ka ʻike ʻana i ka enthalpy o ke kuni ʻana o nā wahie mōʻalihaku no ka hoʻolālā ʻana a me ka hoʻomaikaʻi ʻana i nā mea kanu mana a me nā ʻōnaehana hoʻomehana.
2. Ola kino a me ka lāʻau lapaʻau: I ka hoʻomohala ʻana i nā lāʻau lapaʻau, hiki i ka hoʻomaopopo ʻana i nā loli enthalpy o nā hopena ke hoʻopilikia i ke kūpaʻa o ka lāʻau lapaʻau a me nā ʻano mālama.
3. Kaiapuni: Hoʻokomo pinepine nā hopena kemika i ka lewa a me ka biosphere i nā loli enthalpy e hoʻopilikia i ke kaulike o ka ʻōnaehana ola a me ke aniau honua.
4. Meaʻai a me ka Mahiʻai: ʻO ka hana ʻana i ka meaʻai a me ka biosynthesis o nā hui koʻikoʻi i nā meaola ola e pili pū ana i nā loli enthalpy.
Pani
ʻO ka hoʻomaopopo ʻana i nā loli enthalpy ma lalo o nā kūlana maʻamau he mea nui ia i ka kemika a me ka thermodynamics, ma ke ʻano kumumanaʻo a me ka hana maoli. Hāʻawi ia i nā mea hana waiwai nui no ka wānana a me ka kaohi ʻana i nā hopena o nā hopena kemika, a me ka hāʻawi ʻana i nā ʻike hohonu i ke kahe o ka ikehu i nā ʻōnaehana like ʻole. Ma o nā ʻano hana e like me ke kānāwai o Hess a me nā ʻano hana calorimetry, hiki iā mākou ke ana a hoʻohana i nā loli enthalpy no nā ʻano noi pono like ʻole i ka ʻepekema a me ka ʻenehana.
