Mohlala oa Potso ea Puisano mabapi le Matla a Bond
Pendahuluan
Matla a tlamo ke mohopolo oa bohlokoa k'hemistri o re thusang ho utloisisa matla a hlokahalang ho roba tlamo ka har'a molek'hule. Ka mantsoe a bonolo feela, matla a tlamo ke bongata ba matla a hlokahalang ho arola liathomo tse peli tse kopantsoeng hammoho molek'huleng ka liathomo tse arohaneng. Sehloohong sena, re tla utloisisa mohopolo oa matla a tlamo ka mathata a 'maloa a mehlala le puisano ea ona.
Khopolo ea Matla a Tlamo
Matla a bond a hlahisoa ka li-kilojoule ka mole (kJ/mol), 'me mofuta o mong le o mong oa bond ea lik'hemik'hale o na le matla a bond a fapaneng. Mohlala, matla a bond bakeng sa bond e le 'ngoe ea C-H (carbon-hydrogen) a fapane le matla a bond bakeng sa bond e habeli ea C=O (carbon-oxygen).
Tekanyo e atisang ho sebediswa ho bala phetoho ya enthalpy ya karabelo (\(\Delta H\)) ha ho nahannwa ka matla a tlamo ke:
\[
\Delta H = \Sigma D_{\text{reactants}} – \Sigma D_{\text{products}}
\]
Moo \(D_{\text{reactants}}\) le \(D_{\text{products}}\) e leng matla a tlamahano a amehang ho li-reactant le lihlahisoa. Ka mantsoe a mang, kakaretso ea matla a tlamahano ho li-reactant e tlosa kakaretso ea matla a tlamahano lihlahisoa.
Lipotso tsa Mehlala le Puisano
Potso ea 1
Hoa tsebahala hore karolelano ea matla a tlamo bakeng sa litlamo tse latelang ke:
– HH bond: 436 kJ/mol
– O=O tlamo: 498 kJ/mol
– HO bond: 463 kJ/mol
Bala phetoho ea enthalpy (\(\Delta H\)) bakeng sa karabelo e latelang:
\[
2H_2(g) + O_2(g) \motsu 2H_2O(g)
\]
Puisano:
Mohato oa pele ke ho ngola karabelo le ho bala palo ea litlamo tse teng ho li-reactants le lihlahisoa.
Bakeng sa li-reactant:
– Limolek'hule tse 2 tsa \(H_2\) li bolela hore ho na le libonto tse 2 tsa HH
– Molek'hule e le 'ngoe ea \(O_2\) e bolela hore ho na le 1 O=O bond
Bakeng sa lihlahisoa:
– 2 \(H_2O\) limolek'hule li bolela libonto tse 4 tsa HO
Matla ohle a tlamo ho li-reactants:
\[
2 \makgetlo \mongolo{Eneji ya Bond HH} + 1 \makgetlo \mongolo{Eneji ya Bond O=O}
\]
\[
= 2 \makgetlo a 436 + 1 \makgetlo a 498
\]
\[
= 872 + 498
\]
\[
= 1370 \mongolo{ kJ/mol}
\]
Matla ohle a tlamo sehlahisoa:
\[
4 \makgetlo \mongolo{HO bond eneji}
\]
\[
= 4 \makhetlo a 463
\]
\[
= 1852 \mongolo{ kJ/mol}
\]
Phetoho ea enthalpy (\(\Delta H\)):
\[
\Delta H = \Sigma D_{\text{reactants}} – \Sigma D_{\text{products}}
\]
\[
= 1370 \mongolo{kJ/mol} – 1852 \mongolo{kJ/mol}
\]
\[
= -482 \mongolo{ kJ/mol}
\]
Kahoo, phetoho ea enthalpy bakeng sa karabelo ke \(-482\) kJ/mol.
Potso ea 2
Ho nahanoa hore matla a latelang a tlamo a tsejoa:
– CH bond: 414 kJ/mol
– C=C tlamo: 612 kJ/mol
– HH bond: 436 kJ/mol
Bala phetoho ea enthalpy (\(\Delta H\)) bakeng sa karabelo e latelang:
\[
C_2H_4(g) + H_2(g) \ motsu C_2H_6(g)
\]
Puisano:
Mohato oa pele ke ho ngola karabelo le ho bala palo ea litlamo tse teng ho li-reactants le lihlahisoa.
Bakeng sa li-reactant:
– Molek'hule e le 'ngoe ea \(C_2H_4\) (ethylene) e na le libonto tse 4 tsa CH le bonto e le 'ngoe ea C=C
– Molek'hule e le 1 ea \(H_2\) e na le tlamo e le 1 ea HH
Bakeng sa lihlahisoa:
– Molek'hule e le 'ngoe ea \(C_2H_6\) (ethane) e na le litlamo tse 6 tsa CH le tlamo e le 'ngoe ea CC
Matla ohle a tlamo ho li-reactants:
\[
4 \makgetlo \mongolo{Eneji ya Bond CH} + 1 \makgetlo \mongolo{Eneji ya Bond C=C} + 1 \makgetlo \mongolo{Eneji ya Bond HH}
\]
\[
= 4 \makgetlo a 414 + 1 \makgetlo a 612 + 1 \makgetlo a 436
\]
\[
= 1656 + 612 + 436
\]
\[
= 2704 \mongolo{ kJ/mol}
\]
Matla ohle a tlamo sehlahisoa:
\[
6 \times \text{CH bond energy} + 1 \times \text{CC bond energy}
\]
\[
= 6 \makgetlo a 414 + 1 \makgetlo a 348
\]
\[
= 2484 + 348
\]
\[
= 2832 \mongolo{ kJ/mol}
\]
Phetoho ea enthalpy (\(\Delta H\)):
\[
\Delta H = \Sigma D_{\text{reactants}} – \Sigma D_{\text{products}}
\]
\[
= 2704 \mongolo{kJ/mol} – 2832 \mongolo{kJ/mol}
\]
\[
= -128 \mongolo{ kJ/mol}
\]
Kahoo, phetoho ea enthalpy bakeng sa karabelo ke \(-128\) kJ/mol.
Qetello
Khopolo ea matla a tlamahano ke karolo ea bohlokoa ho ithuteng likarabelo tsa lik'hemik'hale le liphetoho tsa tsona tsa enthalpy. Sehloohong sena, re buisane ka mathata a mabeli a mehlala a bontšang mokhoa oa ho bala liphetoho tsa enthalpy bakeng sa likarabelo ho sebelisoa matla a tlamahano. Kutloisiso ena e bohlokoa haholo lits'ebetsong tse fapaneng tsa lik'hemik'hale, ho tloha ho tsoakong ea lintho tse phelang ho isa nts'etsopele ea mafura. Kutloisiso e tebileng e ka finyelloa ka ho ikoetlisa khafetsa le ho hlahloba mefuta e fapaneng ea likarabelo tsa lik'hemik'hale.
Ka kopo sebelisa mekhoa e hlalositsoeng sehloohong sena e le tataiso ea ho rarolla mathata a matla a tlamahano nakong e tlang, 'me u nahane ka mehloli e meng e eketsehileng ea ho ithuta ho tebisa tsebo ea hau ea k'hemistri ea matla a tlamahano.
