Alkalinity (สภาพด างและ สภาพด าง

1 1 Alkalinity ( ) Alkalinity ( ) (Titration method) acidity Alkalinity (indicator) phenolphthalein methyl orange (endpoint) 1. Standard N HCl stock N HCl CO2 standardized CO2 2.

2 Phenolphthalein indicator phenolphthalein 95% ethanol 60 . 100 . ( phenolphthalein ) 3. Methyl orange indicator methyl orange 500 . 1000 . 4. Sodium thiosulfate solution Na2S2O3 .5H2O 5 200 . 1. 250 . 2 100 .( acidity Alkalinity , 2) 2.

3 M sodium thiosulfate 1 ( .) 3. phenolphthalein indicator 1 methyl orange indicator 2 ( 3 ) 4. 1 phenolphthalein indicator N HCl phenolphthalein . 2 Alkalinity phenolphthalein indicator N NaOH Total acidity 5.

4 2 methyl orange indicator N HCl total Alkalinity methyl orange indicator N NaOH methyl orange acidity acidity Alkalinity acidity Alkalinity (mg/l) ppm CaCO3 Acidity or Alkalinity = A x N x 50,000 as mg/l CaCO3 (.)

5 A = ( .) N = ( N) Acidity 1. mineral acidity carbondioxide acidity 2. acidity 3. Methyl orange acidity H+ (mineral acid) mineral acidity NaOH pH (pH methyl orange ) 4.

6 Methyl orange acidity = 0 Phenolphthalein acidity CO2 acidity (H2CO3) (tannic acid) ferrous sulfate aluminium sulfate . 3 acidity Alkalinity 100 . M Sodium thiosulfate 1 phenolphthalein indicator 3 100.

7 M Sodium thiosulfate 1 Methyl orange indicator 3 - titrate N HCl Titrate N NaOH titrate N NaOH Titrate N HCl - phenolphthalein Alkalinity total acidity methyl orange acidity Total Alkalinity . 4 Alkalinity 1. hydroxide, carbonate bicarbonate Alkalinity 1 1 Alkalinity Result of titration OH- Alkalinity CO3- Alkalinity HCO3- Alkalinity P = O P< T P = T P > T P = T - - - 2P-T (T) - 2P 2P 2(T-P) - T T-2P - - - P = 150 mg/L as CaCO3 T = 200 mg/L as CaCO3 P > OH- Alkalinity = 2P-T = 300-200 = 100 mg/L as CaCO3 CO3- Alkalinity =2(T-P) = 2(200-150) = 100 mg/L as CaCO3 HCO3- Alkalinity = 0 mg/L as CaCO3 2.

8 P = T Jenkin(1977) [OH- ] mg/L as CaCO3 Alkalinity [CO3 2- ] = 2P -2[OH- ] [HCO3 - ] = T-2P +[OH- ] P = [CO3 2- ] + [OH- ] 3. total Alkalinity { [OH- ] + 2[CO3 2- ] + [HCO3 - ] } H 2CO3 Phenolphthalein Alkalinity (phenolphthalein Alkalinity ) { [OH- ] + [CO3 2- ]} HCO3 - 4.

9 Alkalinity Alkalinity 30-500 mg/l 5. pheolphthalein Alkalinity (P) total Alkalinity (T) Alkalinity 1 6. carbonate Alkalinity P 0 T 7. hydroxide Alkalinity P > T 8. bicarbonate Alkalinity P< T . 5 9.

10 Alkalinity neutralize [OH- ] + 2[CO3 2- ] + [HCO3 - ] borate, silicate, phosphate, organic acid 1. mg/L as CaCO3 Alkalinity 100 mg/L as CaCO3 Alkalinity CaCO3 100 . 1 2. Chlorine mg/L methyl orange 3. end point 4.