Chitsanzo cha Mafunso Okambirana za Calorimetry
Mu fizikisi, calorimetry ndi nthambi ya sayansi yomwe imaphunzira kuyeza kutentha mu zochita za mankhwala kapena kusintha kwa thupi. Chida chomwe chimagwiritsidwa ntchito poyesa kuchuluka kwa kutentha chimatchedwa calorimeter. Calorimetry imagwira ntchito yofunika kwambiri, makamaka mu thermodynamics ndi physical chemistry, komwe kusintha kwa mphamvu ya kutentha kumawonedwa ndikuyesedwa.
Mfundo Zoyambira za Calorimetry
Mfundo yaikulu ya calorimetry imachokera ku lamulo losunga mphamvu, lomwe ndi lakuti mphamvu sizingapangidwe kapena kuwonongedwa, koma zitha kusinthidwa kuchokera ku mtundu wina wa mphamvu kupita ku wina. Pankhani ya calorimetry, mphamvu ya kutentha yomwe imatayika ndi dongosololi iyenera kufanana ndi mphamvu ya kutentha yomwe imatengedwa ndi chilengedwe. Chida chachikulu mu kuyesa kwa calorimetry nthawi zambiri chimakhala calorimeter, yomwe ingakhale calorimeter yosavuta, yomwe ndi calorimeter yamadzi, kapena calorimeter yovuta kwambiri, monga calorimeter ya bomba.
Mafomula Oyambira a Calorimetry
Fomula yoyambira mu calorimetry ndi iyi:
\[ Q = m \cdot c \cdot \Delta T \]
Kumene:
– \( Q \) ndi kuchuluka kwa kutentha (mu ma joules kapena ma calories)
– \( m \) ndi kulemera kwa chinthu (mu magalamu kapena ma kilogalamu)
– \( c \) ndi kutentha kwa chinthu (mu J/(g°C) kapena cal/(g°C))
– \( \Delta T \) ndi kusintha kwa kutentha (mu °C)
Tiyeni tiwone zitsanzo za mafunso ndi zokambirana kuti timvetse bwino lingaliro ndi kagwiritsidwe ntchito ka calorimetry.
Zitsanzo za Mafunso ndi Kukambirana 1
Funso:
Chitsulo cha magalamu 200 chimatenthedwa kufika pa 100°C kenako chimaviikidwa mu magalamu 100 a madzi pa 20°C. Kutentha komaliza kwa chisakanizocho ndi 27°C. Dziwani kutentha kwa chitsulocho! (kutentha kwa madzi = 4,18 J/(g°C))
Kukambirana:
Gawo loyamba ndikuwerengera kutentha komwe kumatengedwa ndi madzi. Pogwiritsa ntchito njira yoyambira:
\[ Q_{\text{air}} = m_{\text{air}} \cdot c_{\text{air}} \cdot \Delta T_{\text{air}} \]
Ndi \( m_{\text{air}} = 100 \) magalamu, \( c_{\text{air}} = 4.18 \) J/(g°C), ndi \( \Delta T_{\text{air}} = 27°C – 20°C = 7°C \),
\[ Q_{\text{air}} = 100 \times 4.18 \times 7 = 2926 \text{J} \]
Kutentha komwe kutulutsidwa ndi chitsulocho kuli kofanana ndi kutentha komwe kumatengedwa ndi madzi, kotero:
\[ Q_{\text{metal}} = 2926 \text{J} \]
Kugwiritsa ntchito njira yotenthetsera:
\[ m_{\text{metal}} \cdot c_{\text{metal}} \cdot \Delta T_{\text{metal}} = Q_{\text{metal}} \]
ndi \( m_{\text{metal}} = 200 \) magalamu, \(\Delta T_{\text{metal}} = 100°C – 27°C = 73°C \),
\[ 200 \cdot c_{\text{metal}} \cdot 73 = 2926 \text{ J} \]
\[ c_{\text{metal}} = \frac{2926}{200 \times 73} \]
\[ c_{\text{metal}} = 0.2 \text{ J/(g°C)} \]
Kotero, kutentha kwachitsulo ndi 0.2 J/(g°C).
Zitsanzo za Mafunso ndi Kukambirana 2
Funso:
Chidutswa cha ayezi chokhala ndi kulemera kwa 50 g pa kutentha kwa 0°C chimayikidwa mu 200 g ya madzi pa kutentha kwa 30°C mu calorimeter. Dziwani kutentha komaliza kwa chisakanizocho mutafika pamlingo wa kutentha! (kutentha kwa kusakanikirana kwa ayezi = 334 J/g, kutentha kwapadera kwa madzi = 4,18 J/g°C)
Kukambirana:
Gawo loyamba ndikuwerengera kutentha komwe kumafunika kuti ayezi asungunuke:
\[ Q_{\text{melt}} = m_{\text{es}} \cdot L \]
ndi \( m_{\text{es}} = 50 \) magalamu ndi \( L = 334 \) J/g,
\[ Q_{\text{melting}} = 50 \nthawi 334 = 16700 \text{J} \]
Kenako, pezani kutentha komwe kumatengedwa ndi ayezi atasungunuka kuti kufikire kutentha komaliza \( T \) (poganiza kuti T ndiye kutentha komaliza kwa chisakanizo):
\[ Q_{\text{ice water}} = m_{\text{es}} \cdot c_{\text{air}} \cdot (T – 0°C) \]
ndi \( c_{\text{air}} = 4.18 \text{ J/g°C} \),
\[ Q_{\text{water ice}} = 50 \times 4.18 \times T \]
Kutentha komwe kumatulutsidwa ndi madzi ozizira (kuyambira 30°C mpaka T):
\[ Q_{\text{air}} = m_{\text{air}} \cdot c_{\text{air}} \cdot (30°C – T) \]
ndi magalamu a \( m_{\text{air}} = 200 \) ,
\[ Q_{\text{air}} = 200 \nthawi 4.18 \nthawi (30 – T) \]
Pa kutentha koyenera, kuchuluka kwa kutentha komwe kumatengedwa ndi ayezi (kuti asungunuke ndi kutentha kufika pa T) kudzakhala kofanana ndi kuchuluka kwa kutentha komwe madzi amatulutsa:
\[ Q_{\text{melt}} + Q_{\text{ice water}} = Q_{\text{water}} \]
\[ 16700 + 50 \nthawi 4.18 \nthawi T = 200 \nthawi 4.18 \nthawi (30 - T) \]
\[ 16700 + 209T = 8360 \nthawi (30 - T) \]
\[ 16700 + 209T = 250800 - 8360T \]
\[ 8569T = 234100 \]
\[ T = \frac{234100}{8569} \pafupifupi 27.3°C \]
Motero, kutentha komaliza kwa chisakanizocho chikafika pamlingo wa kutentha kumakhala pafupifupi 27.3°C.
Mapeto
Calorimetry ndi njira yofunika kwambiri mu fizikisi ndi chemistry yomwe imagwiritsidwa ntchito kudziwa kuchuluka kwa mphamvu ya kutentha mu njira ya thupi kapena ya mankhwala. Pogwiritsa ntchito mfundo zoyambira ndi njira za calorimetry, titha kuwerengera magawo osiyanasiyana monga kutentha kwa chinthu, kusintha kwa kutentha, kapena mphamvu yomwe imayamwa/kutulutsidwa mu njira. Munkhaniyi, tayang'ana zitsanzo za mavuto ndi mayankho awo pomvetsetsa calorimetry. Kumvetsetsa bwino mfundo izi ndikofunikira pothetsa mavuto osiyanasiyana a thermodynamic ndi ntchito zina zothandiza.
