Mohlala oa Lipotso tsa Puisano tsa Calorimetry
Fisiks, calorimetry ke lekala la mahlale le ithutang tekanyo ea mocheso liketsong tsa lik'hemik'hale kapa liphetoho tsa 'mele. Sesebelisoa se sebelisetsoang ho lekanya bongata ba mocheso se bitsoa calorimeter. Calorimetry e bapala karolo ea bohlokoa, haholo-holo ho thermodynamics le k'hemistri ea 'mele, moo liphetoho tsa matla a mocheso li bonoang le ho lekanyetsoa.
Melao-motheo ea Motheo ea Calorimetry
Molao-motheo oa motheo oa calorimetry o thehiloe molaong oa paballo ea matla, e leng hore matla a ke ke a bōptjoa kapa a timetsoa, empa a ka fetoloa feela ho tloha mofuteng o mong oa matla ho ea ho o mong. Moelelong oa calorimetry, matla a mocheso a lahlehang ke sistimi a tlameha ho lekana le matla a mocheso a monngoang ke tikoloho. Sesebelisoa se seholo litekong tsa calorimetry hangata ke calorimeter, e ka bang calorimeter e bonolo, e leng calorimeter ea metsi, kapa calorimeter e rarahaneng haholoanyane, joalo ka calorimeter ea bomo.
Mekhoa ea Motheo ea Calorimetry
Foromo ea motheo ea calorimetry ke:
\[ Q = m \cdot c \cdot \Delta T \]
Moo:
– \( Q \) ke bongata ba mocheso (ka li-joule kapa lik'hilojule)
– \( m \) ke boima ba ntho (ka digrama kapa dikhilograma)
– \( c \) ke mocheso o itseng oa ntho (ho J/(g°C) kapa cal/(g°C))
– \( \Delta T \) ke phetoho mochesong (ka °C)
A re shebeng mehlala e meng ea lipotso le lipuisano ho utloisisa hamolemo mohopolo le ts'ebeliso ea calorimetry.
Lipotso tsa Mehlala le Puisano 1
Potso:
Sekotwana sa tšepe sa digrama tse 200 se futhumatsoa ho fihlela ho 100°C ebe se ineloa ka har'a digrama tse 100 tsa metsi ho 20°C. Mocheso oa ho qetela oa motsoako ke 27°C. Fumana mocheso o itseng oa tšepe! (mocheso o itseng oa metsi = 4,18 J/(g°C))
Puisano:
Mohato oa pele ke ho bala mocheso o monngoang ke metsi. Ho sebelisoa foromo ea motheo:
\[ Q_{\text{air}} = m_{\text{air}} \cdot c_{\text{air}} \cdot \Delta T_{\text{air}} \]
Ka \( m_{\text{air}} = 100 \) digrama, \( c_{\text{air}} = 4.18 \) J/(g°C), le \( \Delta T_{\text{air}} = 27°C – 20°C = 7°C \),
\[ Q_{\text{air}} = 100 \times 4.18 \times 7 = 2926 \text{J} \]
Mocheso o ntshwang ke tshepe o tshwana le mocheso o monngwang ke metsi, kahoo:
\[ Q_{\text{metal}} = 2926 \text{J} \]
Ho sebelisa foromo ea mocheso:
\[ m_{\text{metal}} \cdot c_{\text{metal}} \cdot \Delta T_{\text{metal}} = Q_{\text{metal}} \]
ka \( m_{\text{metal}} = 200 \) digrama, \(\Delta T_{\text{metal}} = 100°C – 27°C = 73°C \),
\[ 200 \cdot c_{\text{metal}} \cdot 73 = 2926 \text{ J} \]
\[ c_{\text{metal}} = \frac{2926}{200 \makgetlo a 73} \]
\[ c_{\text{metal}} = 0.2 \text{ J/(g°C)} \]
Kahoo, mocheso o itseng oa tšepe ke 0.2 J/(g°C).
Lipotso tsa Mehlala le Puisano 2
Potso:
Sekotwana sa leqhoa se boima ba 50 g mochesong oa 0°C se kenngoa ka har'a 200 g ea metsi mochesong oa 30°C ka har'a calorimeter. Fumana mocheso oa ho qetela oa motsoako ka mor'a ho fihlela tekanyo ea mocheso! (mocheso oa ho kopana ha leqhoa = 334 J/g, mocheso o itseng oa metsi = 4,18 J/g°C)
Puisano:
Mohato oa pele ke ho bala mocheso o hlokahalang ho qhibilihisa leqhoa:
\[ Q_{\text{melt}} = m_{\text{es}} \cdot L \]
ka \( m_{\text{es}} = 50 \) digrama le \( L = 334 \) J/g,
\[ Q_{\text{melting}} = 50 \makgetlo a 334 = 16700 \text{J} \]
Ka mor'a moo, fumana mocheso o monngoang ke leqhoa ka mor'a ho qhibiliha ho fihlela mochesong oa ho qetela \( T \) (haeba T ke mocheso oa ho qetela oa motsoako):
\[ Q_{\text{water ice}} = m_{\text{es}} \cdot c_{\text{air}} \cdot (T – 0°C) \]
ka \( c_{\text{air}} = 4.18 \text{ J/g°C} \),
\[ Q_{\text{water ice}} = 50 \makgetlo a 4.18 \makgetlo a T \]
Mocheso o ntshwang ke metsi a batang (ho tloha ho 30°C ho isa ho T):
\[ Q_{\text{air}} = m_{\text{air}} \cdot c_{\text{air}} \cdot (30°C – T) \]
ka digrama tse 200,
\[ Q_{\text{air}} = 200 \makgetlo a 4.18 \makgetlo (30 - T) \]
Nakong ea ho leka-lekana ha mocheso, tekanyo ea mocheso o monngoang ke leqhoa (ho qhibiliha le ho futhumatsa ho fihlela ho T) e tla lekana le tekanyo ea mocheso o lokolloang ke metsi:
\[ Q_{\text{melt}} + Q_{\text{water}} = Q_{\text{water}} \]
\[ 16700 + 50 \makhetlo a 4.18 \makhetlo a T = 200 \makhetlo a 4.18 \makhetlo (30 - T) \]
\[ 16700 + 209T = 8360 \makgetlo (30 - T) \]
\[ 16700 + 209T = 250800 – 8360T \]
\[ 8569T = 234100 \]
\[ T = \frac{234100}{8569} \hoo e ka bang 27.3°C \]
Ka hona, mocheso oa ho qetela oa motsoako ka mor'a ho fihlela tekano ea mocheso ke hoo e ka bang 27.3°C.
Qetello
Calorimetry ke mokhoa oa bohlokoa fisiks le k'hemistri o sebelisoang ho fumana hore na matla a mocheso ke bokae ts'ebetsong ea 'mele kapa ea lik'hemik'hale. Re sebelisa melao-motheo ea motheo le mekhoa ea calorimetry, re ka bala liparamente tse fapaneng tse kang mocheso o itseng oa ntho, phetoho ea mocheso, kapa matla a monngoang/a lokolloang ts'ebetsong. Sehloohong sena, re shebile mathata a mohlala le litharollo tsa 'ona moelelong oa ho utloisisa calorimetry. Kutloisiso e ntle ea likhopolo tsena e bohlokoa bakeng sa ho rarolla mathata a fapaneng a thermodynamic le lits'ebetso tse ling tse sebetsang.
