Ihe Nlereanya nke Ajụjụ Mkparịta ụka Thermochemistry
Pendahuluan
Thermochemistry bụ ngalaba kemistri nke na-amụ mmekọrịta dị n'etiti mmeghachi omume kemịkalụ na mgbanwe ike, ọkachasị n'ụdị okpomọkụ. Ọ bụ isiokwu dị mkpa na kemistri anụ ahụ n'ihi na ọ na-enyere anyị aka ịghọta otu esi ebufe ma gbanwee ike n'oge mmeghachi omume kemịkalụ. N'isiokwu a, anyị ga-atụle ọtụtụ nsogbu ihe atụ thermochemistry iji nyere aka mee ka echiche ndị a doo anya.
Ajụjụ Ihe Nlereanya nke 1: Mgbanwe na Enthalpy nke Ọkụ
Ajụjụ:
Ọkụ nke ethanol (C2H5OH) bụ -1367 kJ/mol. Chọpụta ike ewepụtara mgbe ọkụ gbachara mole ethanol abụọ kpamkpam!
Azịza:
Mgbanwe enthalpy nke ọkụ (ΔHc) bụ ike ewepụtara mgbe otu mole nke ihe gbanyere ọkụ kpamkpam na oxygen. Maka ethanol, ΔHc = -1367 kJ/mol.
Ọ bụrụ na ọkụ agbaa mole ethanol abụọ, ike ewepụtara bụ:
\[ \text{Ntọala Ike} = 2 \, \text{mol} \times (-1367 \, \text{kJ/mol}) \]
\[ \ederede{Ike mwepụta} = -2734 \, \ederede{kJ} \]
Ya mere, mgbe ọkụ gbachara mole ethanol abụọ kpamkpam, ike ewepụtara bụ -2734 kJ.
Ajụjụ Ihe atụ nke 2: Ịgbakọ Enthalpy Mmeghachi omume site na Data Enthalpy Formation
Ajụjụ:
Jiri enthalpy ọkọlọtọ nke data nhazi a gbakọọ mmeghachi omume enthalpy nke nhazi nke mmiri vapor:
– \(\Delta H_{\text{f}}^{\circ}(\text{H}_2(g)) = 0 \, \text{kJ/mol}\)
– \(\Delta H_{\text{f}}^{\circ}(\text{O}_2(g)) = 0 \, \text{kJ/mol}\)
– \(\Delta H_{\text{f}}^{\circ}(\text{H}_2\text{O}(g)) = -241.8 \, \text{kJ/mol}\)
Mmeghachi omume:
\[ \ederede{H}_2(g) + \frac{1}{2}\ederede{O}_2(g) \rightarrow \ederede{H}_2\ederede{O}(g) \]
Azịza:
Enwere ike ịgbakọ enthalpy mmeghachi omume (\(\Delta H_{\text{rxn}}\)) site na iji enthalpy ọkọlọtọ nke nhazi (\(\Delta H_{\text{f}}^{\circ}\)) na usoro:
\[ \Delta H_{\text{rxn}} = \Sigma \Delta H_{\text{f}}^{\circ} \text{product} – \Sigma \Delta H_{\text{f}}^{\circ} \text{reactants} \]
Maka mmeghachi omume a:
\[ \Delta H_{\text{rxn}} = \Delta H_{\text{f}}^{\circ}(\text{H}_2\text{O}(g)) – \left[ \Delta H_{\text{f}}^{\circ}(\text{H}_2(g)) + \frac{1}{2} \Delta H_{\text{f}}^{\circ}(\text{O}_2(g)) \right] \]
Tinye enthalpy nke uru nhazi:
\[ \Delta H_{\text{rxn}} = -241.8 \, \text{kJ/mol} – \left[ 0 + \frac{1}{2} \times 0 \right] \]
\[ \Delta H_{\text{rxn}} = -241.8 \, \text{kJ/mol} \]
Ya mere, mmeghachi omume enthalpy maka imepụta uzuoku mmiri bụ -241.8 kJ/mol.
Ajụjụ Ihe atụ nke 3: Iwu Hess
Ajụjụ:
Chọpụta mgbanwe enthalpy (\(\Delta H\)) maka mmeghachi omume ndị a:
\[ \text{C(s)} + \frac{1}{2}\text{O}_2(g) \rightarrow \text{CO(g)} \]
Jiri data ndị a:
1. \(\text{C(s)} + \text{O}_2(g) \rightarrow \text{CO}_2(g) \, \Delta H = -393.5 \, \text{kJ}\)
2. \(\text{CO(g)} + \frac{1}{2}\text{O}_2(g) \rightarrow \text{CO}_2(g) \, \Delta H = -283.0 \, \text{kJ}\)
Azịza:
Jiri Iwu Hess nke na-ekwu na ọ bụrụ na enwere ike igosipụta mmeghachi omume kemịkalụ dị ka mkpokọta nke ọtụtụ mmeghachi omume ndị ọzọ, mgbe ahụ mgbanwe enthalpy nke mmeghachi omume zuru oke bụ mkpokọta mgbanwe enthalpy nke mmeghachi omume ndị ahụ.
Nzọụkwụ 1: Dee mmeghachi omume nke kwesịrị ịgbanwe ma ọ bụ gbanwee ka o kwekọọ na mmeghachi omume ebumnuche:
– Mmeghachi omume (1): \(\text{C(s)} + \text{O}_2(g) \rightarrow \text{CO}_2(g) \, \Delta H = -393.5 \, \text{kJ}\)
– Mmeghachi omume (2): \(\text{CO(g)} + \frac{1}{2}\text{O}_2(g) \rightarrow \text{CO}_2(g) \, \Delta H = -283.0 \, \text{kJ}\)
Nzọụkwụ nke 2: Gbanwee mmeghachi omume (2) wee gbanwee akara nke \(\Delta H\):
\[ \text{CO}_2(g) \rightarrow \text{CO(g)} + \frac{1}{2}\text{O}_2(g) \, \Delta H = 283.0 \, \text{kJ} \]
Nzọụkwụ nke 3: Tinye mmeghachi omume (1) na mmeghachi omume agbangharị (2):
\[ \text{C(s)} + \text{O}_2(g) \rightarrow \text{CO}_2(g) \, \Delta H = -393.5 \, \text{kJ} \]
\[ \text{CO}_2(g) \rightarrow \text{CO(g)} + \frac{1}{2}\text{O}_2(g) \, \Delta H = 283.0 \, \text{kJ} \]
Nzọụkwụ nke 4: Tinye mmeghachi omume abụọ ahụ:
\[ \text{C(s)} + \text{O}_2(g) + \text{CO}_2(g) \rightarrow \text{CO}_2(g) + \text{CO(g)} + \frac{1}{2}\text{O}_2(g) \]
Mfe ime ka ihe dị mfe pụta na:
\[ \text{C(s)} + \frac{1}{2} \text{O}_2(g) \rightarrow \text{CO(g)} \]
Mgbanwe zuru oke nke enthalpy (\(\Delta H\)):
\[ \Delta H = -393.5 \, \text{kJ} + 283.0 \, \text{kJ} = -110.5 \, \text{kJ} \]
Ya mere, mgbanwe enthalpy maka mmeghachi omume bụ -110.5 kJ.
Ajụjụ Ihe Nlereanya nke 4: Kalọrịmetị
Ajụjụ:
N'ime nnwale kalori, a na-ekpo ọkụ gram 50 nke mmiri (c = 4.18 J/g°C) site na 25°C ruo 75°C. Gbakọọ ọnụọgụ okpomọkụ (q) achọrọ.
Azịza:
Enwere ike ịgbakọ oke okpomọkụ (q) achọrọ iji kpoo mmiri ọkụ site na iji usoro a:
\[ q = m \cdot c \cdot \Delta T \]
– m = oke mmiri = 50 g
– c = ikike okpomọkụ kpọmkwem = 4.18 J/g°C
– \(\Delta T = \) mgbanwe n'ọnọdụ okpomọkụ \( = 75°C – 25°C = 50°C \)
\[ q = 50 \, \ederede{g} \oge 4.18 \, \ederede{J/g°C} \oge 50°C \]
\[ q = 10450 \, \ederede{J} \]
Ya mere, oke okpomọkụ achọrọ iji kpoo gram 50 nke mmiri site na 25°C ruo 75°C bụ 10450 J.
Penutup
Mkparịta ụka nke nsogbu ihe atụ dị n'elu na-enye nkọwa zuru ezu nke otu esi etinye echiche thermochemical n'ọrụ iji dozie nsogbu dị iche iche metụtara mmeghachi omume kemịkalụ na mgbanwe ike. Thermochemistry dị oke mkpa n'ọtụtụ ngalaba, gụnyere ụlọ ọrụ mmepụta ihe, ike, na nnyocha sayensị, n'ihi na ọ na-enye anyị ohere ịghọta ma jikwaa mgbanwe ike nke na-eme na mmeghachi omume kemịkalụ. Site na nghọta dị mma nke thermochemistry, anyị nwere ike ịmepụta usoro dị irè karị ma mepụta teknụzụ ọhụrụ, nke na-adịghị emerụ gburugburu ebe obibi ahụ.
