Imibuzo Yezibonelo kanye Nengxoxo Yokucindezeleka Kwezindawo Zokuqandisa Kwezixazululo
Ukucindezeleka kwamaphuzu okuqandisa kuyisici esibalulekile esihambisana nokuhlangana kwamakhemikhali esisombululo. Sithonya izinqubo eziningi zebhayoloji, zamakhemikhali, kanye nezezimboni. Lesi sihloko sixoxa ngezibonelo eziningana zokucindezeleka kwamaphuzu okuqandisa futhi sinikeza izingxoxo ezinemininingwane ukuze kucaciswe lo mqondo.
Ukuqonda Ukucindezeleka Kwe-Freezing Point
Ukucindezeleka kwephuzu lokuqandisa yisimo lapho iphuzu lokuqandisa le-solvent lehliswa khona lapho kungezwa i-solute kuso. Lo mphumela uyisimo esihambisanayo, okusho ukuthi ukucindezeleka kwephuzu lokuqandisa kuncike enanini lezinhlayiya ze-solute esixazululweni, hhayi ekutheni i-solute ingubani.
I-equation ejwayelekile esetshenziselwa ukubala ukucindezeleka kwamaphuzu okuqandisa yile:
\[
\Delta T_f = K_f \cdot m
\]
Di mana:
– \(\Delta T_f\) ukucindezeleka kwe-frozen point.
– \(K_f\) isici esiyingqayizivele sokungaguquguquki kwephuzu lokuqandisa kwe-solvent.
– \(m\) yi-molality yesisombululo (ama-moles e-solute/kg ye-solvent).
Imibuzo Yesibonelo Yokucindezeleka Kwama-Freezing Point
umbuzo 1
Kuyaziwa:
– Isixazululo senziwa ngokuncibilikisa amagremu ama-5 e-NaCl (isisindo se-molar = 58.5 g/mol) kumagremu angama-200 amanzi.
– Isilinganiso sokucindezeleka kwephuzu lokuqandisa (K_f) samanzi singama-1.86 °C •kg/mol.
Umbuzo:
Bala ukwehla kwephuzu lokuqandisa kwalesi sixazululo.
Ingxoxo:
1. Bala ubuningi besisombululo (m):
Okokuqala, sibala inani lama-moles e-NaCl:
\[
\text{mol NaCl} = \frac{\text{mass of NaCl (g)}}{\text{molar weight (g/mol)}} = \frac{5 \text{ g}}{58.5 \text{ g/mol}} = 0.0855 \text{ mol}
\]
Bese sibala i-molality (ama-moles e-solute/kg ye-solvent):
\[
\text{molality} = \frac{\text{mol NaCl}}{\text{mass of solvent (kg)}} = \frac{0.0855 \text{ mol}}{0.2 \text{ kg}} = 0.4275 \text{ m}
\]
2. Bala ukucindezeleka kwe-freezing point (\(\Delta T_f\)):
\[
\Delta T_f = K_f \cdot m = 1.86 \text{ °C•kg/mol} \cdot 0.4275 \text{ m} = 0.79545 \text{ °C}
\]
Ngakho-ke, lesi sixazululo sizobhekana nokwehla kwamaphuzu okuqandisa okungu-0.79545 °C.
umbuzo 2
Kuyaziwa:
– Isixazululo siqukethe amagremu ayi-10 e-glucose (C₆H₁₂O₆, isisindo se-molar = 180 g/mol) encibilikiswe kumagremu angu-250 amanzi.
– Isilinganiso sokucindezeleka kwe-frosting point yamanzi singu-1.86 °C •kg/mol.
Umbuzo:
Iyini inkinga yokuncipha kwe-frozen point kwalesi sixazululo se-glucose?
Ingxoxo:
1. Bala ubuningi besisombululo (m):
Okokuqala, sibala inani lama-moles e-glucose:
\[
\text{mol glucose} = \frac{\text{mass of glucose (g)}}{\text{molar weight (g/mol)}} = \frac{10 \text{ g}}{180 \text{ g/mol}} = 0.0556 \text{ mol}
\]
Bese sibala i-molality (ama-moles e-solute/kg ye-solvent):
\[
\text{molality} = \frac{\text{mol glucose}}{\text{mass of solvent (kg)}} = \frac{0.0556 \text{ mol}}{0.25 \text{ kg}} = 0.2224 \text{ m}
\]
2. Bala ukucindezeleka kwe-freezing point (\(\Delta T_f\)):
\[
\Delta T_f = K_f \cdot m = 1.86 \text{ °C•kg/mol} \cdot 0.2224 \text{ m} = 0.413664 \text{ °C}
\]
Ngakho-ke, isixazululo se-glucose sizobhekana nokwehla kwephuzu lokubanda elingu-0.413664 °C.
umbuzo 3
Kuyaziwa:
– Isixazululo senziwa ngokuncibilikisa amagremu angu-20 e-urea (NH₂CONH₂, isisindo se-molar = 60 g/mol) kumagremu angu-500 amanzi.
– Isilinganiso sokucindezeleka kwephuzu lokuqandisa (K_f) samanzi singama-1.86 °C •kg/mol.
Umbuzo:
Bala ukwehla kwephuzu lokuqandisa kwalesi sixazululo.
Ingxoxo:
1. Bala ubuningi besisombululo (m):
Okokuqala, sibala inani lama-moles e-urea:
\[
\text{mole urea} = \frac{\text{mass of urea (g)}}{\text{molar weight (g/mol)}} = \frac{20 \text{ g}}{60 \text{ g/mol}} = 0.3333 \text{ mol}
\]
Bese sibala i-molality (ama-moles e-solute/kg ye-solvent):
\[
\text{molality} = \frac{\text{mol urea}}{\text{mass of solvent (kg)}} = \frac{0.3333 \text{ mol}}{0.5 \text{ kg}} = 0.6666 \text{ m}
\]
2. Bala ukucindezeleka kwe-freezing point (\(\Delta T_f\)):
\[
\Delta T_f = K_f \cdot m = 1.86 \text{ °C•kg/mol} \cdot 0.6666 \text{ m} = 1.240476 \text{ °C}
\]
Ngakho-ke, ikhambi lizobhekana nokwehla kwezinga lokubanda elingu-1.240476°C.
umbuzo 4
Kuyaziwa:
– Isixazululo siqukethe amagremu ayi-15 e-acetic acid (CH₃COOH, isisindo se-molar = 60 g/mol) encibilikiswe kumagremu angu-300 amanzi.
– Isilinganiso sokucindezeleka kwephuzu lokuqandisa (K_f) samanzi singama-1.86 °C •kg/mol.
Umbuzo:
Iyini i-frosting point depression yalesi sixazululo se-acetic acid?
Ingxoxo:
1. Bala ubuningi besisombululo (m):
Okokuqala, sibala inani lama-moles e-acetic acid:
\[
\text{mol of acetic acid} = \frac{\text{mass of acetic acid (g)}}{\text{molar weight (g/mol)}} = \frac{15 \text{ g}}{60 \text{ g/mol}} = 0.25 \text{ mol}
\]
Bese sibala i-molality (ama-moles e-solute/kg ye-solvent):
\[
\text{molality} = \frac{\text{mol of acetic acid}}{\text{mass of solvent (kg)}} = \frac{0.25 \text{ mol}}{0.3 \text{ kg}} = 0.8333 \text{ m}
\]
2. Bala ukucindezeleka kwe-freezing point (\(\Delta T_f\)):
\[
\Delta T_f = K_f \cdot m = 1.86 \text{ °C•kg/mol} \cdot 0.8333 \text{ m} = 1.55 \text{ °C}
\]
Ngakho-ke, ikhambi lizobhekana nokwehla kwezinga lokubanda elingu-1.55°C.
Isiphetho
Ukucindezeleka kwephuzu lokuqandisa kuyisici esibalulekile esihambisanayo ezinhlotsheni ezahlukene zezicelo zesayensi nezezimboni. Ngokuqonda ukuthi singabala kanjani ukucindezeleka kwephuzu lokuqandisa, singabikezela ukuthi izixazululo ezahlukene zizothinta kanjani iphuzu lokuqandisa lesisombululo. Lesi sihloko sixoxe ngezinkinga eziningana zezibonelo kanye nendlela yokubala ukucindezeleka kwephuzu lokuqandisa ukuze uthole izixazululo, sikunikeze isisekelo esiqinile ekuqondeni umqondo wokucindezeleka kwephuzu lokuqandisa.
