Name
2004-04-29 03:28:27 | Hit : 14277 | Vote : 4293
Subject
Chapter 3. Water
¢Ñ water molecule
4°³ÀÇ hydrogen bonds¸¦ °¡Áú ¼ö ÀÖ´Ù.
¨ç ¼·Î ¼·Î °áÇյǾî ÀÖ¾î ¿Âµµº¯È°¡ ´ú ÇÏ´Ù.
¨è ¹°ÀÇ Àå·ÂÀÌ ¼¼´Ù
¡à Water moleculeÀÇ cohesion
¢Ñ cohesion
hydrogen bond°¡ µ¿ÀÏÇÑ substrate¸¦ ÇÔ²² ºÙµå´Â Çö»ó. Áï, ¹°ºÐÀÚ¿Í ¹°ºÐÀÚ°£ÀÇ ²ø¾î´ç±â´Â Çö»ó
¡æ plant¿¡¼ gravity¸¦ ±Øº¹ÇÏ°í waterÀÇ À̵¿À» °¡´ÉÄÉÇÏ´Â ¿øµ¿·Â
¢Ñ adhesion
ÇÑ substance°¡ ´Ù¸¥ substance¿¡ ´Þ¶óºÙ´Â Çö»ó. Áï ¹°ºÐÀÚ°¡ ¹°ºÐÀÚ ¿Ü¿¡ ´Ù¸¥ °Í¿¡ ´Þ¶óºÙ´Â Çö»ó
¢Ñ surface tension (Ç¥¸éÀå·Â)
liguidÀÇ surface¸¦ strechÇϰųª breakÇϴµ¥ ¾ó¸¶³ª ¾î·Á¿î°¡ÀÇ Á¤µµ
¡à waterÀÇ ¿ÂµµÁ¶Àý
water´Â ´õ¿î °ø±â¿¡¼ heat¸¦ Èí¼öÇÏ¿© air temperature¸¦ ¾ÈÁ¤È½ÃÅ°°í, Âù°ø±â¿¡¼´Â heat¸¦ ¹æÃâÇÏ¿© air temperature¸¦ ¾ÈÁ¤È½ÃŲ´Ù.
- kinetic energy : the energy of motion
- heat : matterÀÇ body¿¡¼ molecular motion¿¡ ÀÇÇÏ¿© »ý±ä kinetic energyÀÇ ÃÑ ¾çÀ» ÀǹÌ
- temperature : moleculeÀÇ average kinetic energy¿¡ ÀÇÇÑ heatÀÇ intensity¸¦ ÀǹÌ
- calorie (Cal) : 1gÀÇ waterÀÇ ¿Âµµ¸¦ 1¡ÆC ¿Ã¸®´Âµ¥ ¼Ò¿äµÇ´Â heat energyÀÇ ¾çÀ» ÀǹÌ
1 J = 0.239 cal, 1 cal = 4.184 J
¢Ñ water's high specific heat
temperature¸¦ stabilizeÇÏ´Â water ability´Â high specific heat¿¡ ºñ·ÊÇÑ´Ù.
- substanceÀÇ high specific heat
substanceÀÇ 1gÀ» 1¡ÆC¸¸Å ¿Ã¸®°Å³ª ³»¸± ¶§, ¼Ò¿äµÇ´Â Èí¼öÇϰųª ¹æÃâÇؾßÇÏ´Â heatÀÇ ¾çÀ» ÀǹÌ
¢Ñ evaporative cooling
liguid ¡æ gas ·Î º¯ÇÏ´Â °ÍÀ» evaporationÀ̶ó ÇÑ´Ù.
liquid¿¡¼ molecule °£ÀÇ attractionÀ» ±Øº¹ÇÒ¸¸Å »¡¸® ¿òÁ÷À̸é water moleculeÀº gas·Î º¯ÇÒ ¼ö ÀÖ´Ù.
¢Ñ heat of vaporization
liquid°¡ gaseous state·Î ¹Ù²Ù±â À§ÇØ substanceÀÇ 1gÀÌ Èí¼öÇؾßÇÏ´Â heatÀÇ ¾ç
ex. room temperature¿¡¼ water¸¦ evaporateÇϱâ À§Çؼ´Â 580 calÀÇ heat°¡ ÇÊ¿äÇÏ´Ù.
¢Ñ evaporative cooling
substrate°¡ evaporateµÇ¸é¼ ±× µÚ¿¡ ³²°ÜÁø liquidÀÇ surface´Â ¿Âµµ°¡ ³»·Á°£´Ù.
¡æ evaporative cooling of water´Â overheatingÀ» ¹æÁöÇÔÀ¸·Î¼ temperature¸¦ stabilizeÇÑ´Ù.
¡à »ý¸íüÀÇ solventÀÎ water
¼³ÅÁ(solute ; ³ì´Â ¹°Áú) + ¹°(solvent ; ³ìÀÌ´Â ¹°Áú) ¡æ ¼³ÅÁ¹°(solution ; µÎ°³ ÀÌ»óÀÇ substance°¡ homogenous mixture¸¦ ÀÌ·é liquid)
- aqueous solution : sovent°¡ waterÀÎ °Í
- water soluble : inonic compound, polar compound
- hydrophilic : hydro (water) + philic (love) water¿¡ affilnity¸¦ °¡Áö´Â substance
- hydrophobic : hydro (water) + phobic (fear) water¿¡ dissolveµÇÁö ¾Ê°Å³ª affilnity°¡ ¾ø´Â substance ¡æ non ionic, nonpolar molecule
¡à Solute concentration in Aqueous solutions
¢Ñ mole (mol)
substanceÀÇ molecular weightÀÇ number¿Í °°´Ù.
ex. sucroseÀÇ 1 mol ÀÇ weight
C12H22O11 = (C: 12 x 12) + (H: 1 x 22) + (O: 16 x 11) = 176 daltonsÀÌ 1molÀÌ´Ù.
1°³ hydrogen atom = 1 daton
¢Ñ molecular weight (ºÐÀÚ·®)
molecule¿¡¼ÀÇ ¸ðµç atomsÀÇ weightsÀÇ ÃÑÇÕ
C12H22O11 = (C: 12 x 12) + (H: 1 x 22) + (O: 16 x 11) = 176 daltons
¡Å sucrose 1 molÀ» ¾ò±â À§Çؼ´Â 342gÀÇ sucrose°¡ ÇÊ¿äÇÏ´Ù.
¢Ñ Avogadro's number
1 mole¿¡¼ÀÇ moleculesÀÇ number = 6.02 x 10^23°³
- 10 daltonÀÇ A substance 10 g
- 100 daltonÀÇ B substance 100 g
¡Å ÀÌ µÑÀº °°ÀÌ 6.02 x 10^23°³ÀÇ moleculeÀ» °¢°¢ °¡Áö°í ÀÖ´Ù.
ex. 6.02 x 10^23°³ÀÇ sucrose moleculeÀ» °¡Áø table sugarÀÇ ¹«°Ô´Â 342gÀÌ´Ù.
ethyle alcohol (C2H6O)ÀÇ 1 mole ¶ÇÇÑ 6.02 x 10^23°³ÀÇ molecules¸¦ °¡ÁöÁö¸¸, 46g ÀÌ´Ù.
¢Ñ Molarity (¸ô³óµµ)
solutionÀÇ 1 liter´ç soluteÀÇ moleÀÇ ¼ö.
Áï, mol / 1 L = ½ÇÁ¦ g ¼ö / ºÐÀÚ·® / 1 L
1molÀÇ ºÐÀÚ·®À» °¡Áø substance¿¡ ¹°À» ³Ö¾î 1L¸¦ ¸¸µé¾úÀ» ¶§¸¦ ±× ºÐÀÚÀÇ 1MÀ̶ó ÇÑ´Ù.
¡à pH
¢Ñ dissociaton of water molecules
H2O ¡ê (H+ ; hydrogen ion) + (OH- ; hydroxide ion)
hydrogen ion°ú hydroxide ionÀº very reactiveÇÏ¿© cell's protein°ú ´Ù¸¥ complex molecules¸¦ Á¶±×¸¶ÇÑ ³óµµÀÇ º¯È·Îµµ ¿µÇâÀ» ÁÙ ¼ö ÀÖ´Ù.
¢Ñ acids and bases
pure water¿¡¼ H+ ion°ú OH- ionÀÇ ³óµµ´Â µ¿ÀÏÇÏ´Ù.
25¡ÆC¿¡¼ 10^-7 MÀ¸·Î µ¿ÀÏ
- Acid : soultion¿¡ Ãß°¡ÀûÀ¸·Î hydrogen ionÀ» ÁÖ´Â °Í ¡æ solution¿¡¼ H+ÀÇ ³óµµ°¡ Áõ°¡ÇÏ°Ô µÊ
- acid soultion : OH- ³óµµº¸´Ù H+ÀÇ ³óµµ°¡ ´õ ¸¹Àº solution
- base : solution¿¡¼ H+ ionÀÇ ³óµµ¸¦ °¨¼Ò½ÃÅ°´Â substance
NaOH ¡æ (Na+) + (OH-) ; °¿°±â
(NH3) + (H+) ¡ê (NH4+) ; ¾à¿°±â
- base solution : H+ ionÀÇ ³óµµº¸´Ù OH- ionÀÇ ³óµµ°¡ ´õ ³ôÀº solution
- neutral : H+¿Í OH- ³óµµ°¡ µ¿ÀÏÇÑ substance
¢Ñ pH scale
[H+] [OH-] = 10^-14 M^2
[H+] = 10^-7 M, [OH-] = 10^-7 M at 25¡ÆC neutral state
¡Å pH = - log[H+] ¡æ log10^-7 = - (-7) = 7
- pH °ª ¡é : H+ ionÀÇ ³óµµ ¡è, OH- ion ³óµµ ¡é
- pH °ª ¡è : H+ ionÀÇ ³óµµ ¡é, OH- ion ³óµµ ¡è
cf. pH 7Àº pH 8º¸´Ù 10¹è ´õ acidicÇÏ´Ù. pH 3Àº pH 6º¸´Ù 10^3¹è Áï, 1000¹è ´õ acidicÇÏ´Ù.
biological fluids´Â pH 8 ~ pH 6 »çÀÌ¿¡ ÀÖ´Ù.
¢Ñ Buffer
living cellÀÇ internal pH´Â 7¿¡ °¡±õ´Ù.
cellÀÇ chemical processes´Â hydrogen°ú hydroxide ionsÀÇ ³óµµ¿¡ ¸Å¿ì ¹Î°¨ÇÏ¿© pHÀÇ Á¶±×¸¶ÇÑ º¯È°¡ harmful ÇÒ ¼ö ÀÖ´Ù.
- buffer
H+ ion°ú OH- ionÀÇ ³óµµº¯È¸¦ ÃÖ¼ÒÈÇÏ´Â substance¸¦ ÀǹÌ
°ÅÀÇ ¸ðµç buffer´Â hydrogen ion°ú reversibly combineÇÏ´Â weak acidÀ̰ųª weak baseÀÌ´Ù.
ex. biological solution buffer ; Carbonic acid (H2CO3)
- »ýü ³»¿¡¼ pH°¡ ¿À¸£¸é Áï, »ýü³» H+ ionÀÇ ³óµµ°¡ ÀûÀ» ¶§ Áõ°¡½ÃÄÑÁÖ´Â ¹æÇâÀ¸·Î ¹ÝÀÀÀÌ ÁøÇàµÈ´Ù.
H2CO3 (H+ donor ; acid) ¡æ (HCO3- ; H+ acceptor, base, bicarbonate ion) + (H+ ; hydrogen ion)
- »ýü ³»¿¡¼ pH°¡ ³»·Á°¡¸é Áï, »ýü³» H+ ionÀÇ ³óµµ°¡ ¸¹À» ¶§ °¨¼Ò½ÃÄÑÁÖ´Â ¹æÇâÀ¸·Î ¹ÝÀÀÀÌ ÁøÇàµÈ´Ù.
(HCO3- ; H+ acceptor, base, bicarbonate ion) + (H+ ; hydrogen ion) ¡æ H2CO3 (H+ donor ; acid)
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