Nā nīnau hoʻohālike a me ke kūkākūkā ʻana o ka hoʻokiʻekiʻe ʻana o ka paila kiko o nā hopena
Pendahuluan
ʻO ka hoʻokiʻekiʻe ʻana o ke kiko paila he hanana colligative e hana ʻia ke hoʻohui ʻia kahi solute i kahi solvent. Pili kēia hanana i ka hoʻonui ʻia ʻana o ke kiko paila o kahi hopena i hoʻohālikelike ʻia me ke kiko paila o ka solvent maʻemaʻe. I ke kemika, he mea koʻikoʻi ka hoʻomaopopo ʻana i ka hoʻokiʻekiʻe ʻana o ke kiko paila, ʻoiai ma ke ʻano o nā hopena kemika, nā kaʻina hana hoʻokaʻawale, a me ka nānā ʻana i nā lāʻau lapaʻau. Manaʻo kēia ʻatikala e hōʻike i nā pilikia hoʻohālike like ʻole a me nā kūkākūkā e pili ana i ke kumumanaʻo o ka hoʻokiʻekiʻe ʻana o ke kiko paila.
Kumumanaʻo Kumu
ʻO ke kiʻekiʻe o ke kiko paila he hanana ia e ʻoi aku ai ke kiʻekiʻe o ke kiko paila o kahi hopena ma mua o ke kiko paila o ka mea hoʻoheheʻe maʻemaʻe. Ke hoʻohui ʻia kahi solute (non-volatile) i kahi mea hoʻoheheʻe, e emi ana ke kaomi mahu o ka mea hoʻoheheʻe. ʻO ka hopena, pono ka mahana kiʻekiʻe e hoʻokō ai i ke kaomi mahu like me ke kaomi waho. No laila, ʻoi aku ke kiʻekiʻe o ke kiko paila o ka hopena.
ʻO ke kaulike i hoʻohana ʻia no ka helu ʻana i ka piʻi ʻana o ka paila kiko:
\[ \Delta T_b = K_b \cdot m \]
Ma hea:
– \(\Delta T_b\) = piʻi ʻana o ka paila,
– \(K_b\) = ebulioscopic constant (ʻokoʻa no kēlā me kēia mea hoʻoheheʻe),
– \(m\) = molality o ka hopena (moles o ka solute no ke kilokani o ka mea hoʻoheheʻe).
Nā Nīnau Laʻana a me ke Kūkākūkā
E kūkākūkā kākou i kekahi mau pilikia hoʻohālike e hoʻomaopopo maikaʻi ai i kēia manaʻo.
Laʻana Nīnau 1
Nīnau: He aha ke kiʻekiʻe o ka paila ʻana o kahi hopena e loaʻa ana he 2 moles o ka glucose (\(C_6H_{12}O_6\)) i hoʻoheheʻe ʻia i loko o 1 kg o ka wai? Ua ʻike ʻia ʻo ke kūpaʻa ebulioscopic o ka wai (\(K_b\)) he 0,512 °C·kg/mol.
Kūkākūkā:
1. E hoʻoholo i ka molality o ka hopena:
\[ m = \frac{\text{moles of solute}}{\text{kg solvent}} = \frac{2 \; \text{mol}}{1 \; \text{kg}} = 2 \; \text{m} \]
2. E helu i ka piʻi ʻana o ke kiko paila me ka hoʻohana ʻana i ka hoohalike:
\[ \Delta T_b = K_b \cdot m \]
\[ \Delta T_b = 0.512 \; °C·kg/mol \times 2 \; m\]
\[ \Delta T_b = 1.024 °C \]
No laila, ʻo ka piʻi ʻana o ke kiko paila o ka hopena he 1.024 °C.
Laʻana Nīnau 2
Nīnau: E helu i ka piʻi ʻana o ke kiko paila no kahi hopena e loaʻa ana he 0,3 mol o NaCl i loko o 500 grams o ka wai (\(K_b\) wai = 0.512 °C·kg/mol). Manaʻo ʻia e hoʻokaʻawale loa ʻo NaCl i loko o ka wai.
Kūkākūkā:
1. E hoʻoholo i ka molality o ka hopena:
\[ \text{Ka nuipa o ka mea hoʻoheheʻe ma kg} = 500 \; \text{g} = 0.5 \; \text{kg} \]
\[ m = \frac{\text{moles of solute}}{\text{kg solvent}} = \frac{0.3 \; \text{mol}}{0.5 \; \text{kg}} = 0.6 \; \text{m} \]
2. ʻOiai ʻo NaCl e hoʻokaʻawale i nā iona \(Na^+\) a me \(Cl^-\), ʻo ka huina o nā ʻāpana he pālua ia o ka helu o nā molekala NaCl i loaʻa.
\[ i = 2 \; (\text{van 't Hoff kumu no NaCl}) \]
3. E helu i ka piʻi ʻana o ke kiko paila me ka hoʻohana ʻana i ka hoohalike:
\[ \Delta T_b = K_b \cdot m \cdot i \]
\[ \Delta T_b = 0.512 \; °C·kg/mol \times 0.6 \; m \times 2 \]
\[ \Delta T_b = 0.6144 °C \]
No laila, ʻo ka piʻi ʻana o ke kiko paila o ka hopena he 0.6144 °C.
Laʻana Nīnau 3
Nīnau: He aha ka piʻi ʻana o ke kiko paila inā hoʻoheheʻe ʻia he 0.5 mol o ka sucrose (\(C_{12}H_{22}O_{11}\)) i loko o 1.5 kg o ka wai? \(K_b\) o ka wai = 0.512 °C·kg/mol.
Kūkākūkā:
1. E hoʻoholo i ka molality o ka hopena:
\[ m = \frac{\text{moles of solute}}{\text{kg solvent}} = \frac{0.5 \; \text{mole}}{1.5 \; \text{kg}} = \frac{0.5}{1.5} \; \text{m} = 0.333 \; \text{m} \]
2. ʻOiai ʻaʻole e hoʻokaʻawale ʻia ka sucrose, ʻo ka van 't Hoff factor (\(i\)) he 1.
3. E helu i ka piʻi ʻana o ke kiko paila me ka hoʻohana ʻana i ka hoohalike:
\[ \Delta T_b = K_b \cdot m \]
\[ \Delta T_b = 0.512 \; °C·kg/mol \times 0.333 \; m\]
\[ \Delta T_b = 0.1705 °C \]
No laila, ʻo ka piʻi ʻana o ke kiko paila o ka hopena he 0.1705 °C.
Laʻana Nīnau 4
Nīnau: ʻO kahi hopena i hana ʻia mai 0.25 mol o ka urea (\(NH_2CONH_2\)) i loko o 2000 grams o ka wai e ʻike i kahi piʻi ʻana o ke kiko paila. E helu i ka piʻi ʻana o ke kiko paila. ʻO \(K_b\) no ka wai he 0.512 °C·kg/mol.
Kūkākūkā:
1. E hoʻoholo i ka molality o ka hopena:
\[ \text{Ka nuipa o ka mea hoʻoheheʻe ma kg} = 2000 \; \text{g} = 2 \; \text{kg} \]
\[ m = \frac{\text{moles of solute}}{\text{kg solvent}} = \frac{0.25 \; \text{mol}}{2 \; \text{kg}} = 0.125 \; \text{m} \]
2. ʻOiai ʻaʻole e hoʻokaʻawale ʻia ka urea i ka wai, ʻo ka van 't Hoff factor (\(i\)) he 1.
3. E helu i ka piʻi ʻana o ke kiko paila me ka hoʻohana ʻana i ka hoohalike:
\[ \Delta T_b = K_b \cdot m \]
\[ \Delta T_b = 0.512 \; °C·kg/mol \times 0.125 \; m\]
\[ \Delta T_b = 0.064 \; °C \]
No laila, ʻo ka piʻi ʻana o ke kiko paila o ka hopena he 0.064 °C.
Ka hopena
He manaʻo koʻikoʻi ka hoʻokiʻekiʻe ʻana o ke kiko paila i ka kemika e wehewehe ana i ke ʻano o ka hopena o ka solute i ke kiko paila o kahi hopena. Hōʻike ka pilikia laʻana ma luna pehea e helu ai i ka hoʻokiʻekiʻe ʻana o ke kiko paila me ka hoʻohana ʻana i nā manaʻo o ka molality a me ka van 't Hoff factor. He mea pono kēia ʻike i nā ʻano noi kemika like ʻole, me ka nānā ʻana i ka hale hana a me ka hoʻomohala ʻana i nā lāʻau lapaʻau. ʻO ka hoʻomaopopo ʻana i kēia hanana e hāʻawi i ka ʻike hohonu i nā waiwai o nā mea i loko o ka hopena.
