Phenolphthalein alkalinity is determined by titration to a pH of 8.3 and indicates the total hydroxide and half the carbonate present. Total alkalinity is determined by titration to a pH of 5.1, 4.8, 4.5 or 3.7 depending upon the amount of carbon dioxide present.
What is the formula for the calculation of alkalinity?
Calculation of Alkalinity, Hydroxide, Carbonate, and Bicarbonate
| Constituent | Units | Equation |
|---|---|---|
| Alko | meq/L | 1000 (B) Ca (CF) / Vo |
| mg/L as CaCO3 | 50044 (B) Ca (CF) / Vo | |
| OH- | meq/L | 1000 Kw’ 10pH |
| mg/L as OH- | 17007 Kw’ 10pH |
Can we use phenolphthalein indicator for determination of total alkalinity?
The alkalinity of water can be determined by titrating the water sample with Sulphuric acid of known values of pH, volume and concentrations. For the pH more than 8.3, add phenolphthalein indicator, the colour changes to pink colour. This pink colour is due to presence of hydroxyl ions.
How do you calculate total alkalinity as caco3?
Solving for alkalinity yields: Alk(meq/L)=3.9 meq/mL. To calculate alkalinity as calcium carbonate, use this formula to calculate the alkalinity in concentration of calcium carbonate (CaCO3). Insert the values into the formula to determine the alkalinity as CaCO3: Alk(mg/L as CaCO3)=(50044xBxCaxCF)÷Vs.
What is phenolphthalein alkalinity and total alkalinity?
Phenolphthalein alkalinity measures the hydroxides and half the carbonates at a pH 8.3. Total alkalinity measures all carbonate, bicarbonate, and hydroxide alkalinity at a pH 4.5 (approximately). Phenolphthalein alkalinity is a subset of total alkalinity.
What is phenolphthalein alkalinity?
Phenolphthalein alkalinity is a specific category of alkalinity. It is determined by titrating to pH 8.3 (where phenolphthalein changes colour). If you are titrating OH- with a strong acid, the titration curve looks like this. Thus, phenolphthalein alkalinity gives the total hydroxide and half the carbonate level.
Why alkalinity is measured as CaCO3?
Why is alkalinity reported as “mg/L as CaCO3”? Units of mg/L are a “mass dissolved in a liquid.” Reporting alkalinity as “mg/L as CaCO3” specifies that the sample has an alkalinity equal to that of a solution with a certain amount of calcium carbonate (CaCO3) dissolved in water.
How do you calculate P and M alkalinity?
From these three alkalinities it is sufficient to measure M and P alkalinity only; the caustic alkalinity is then given by 2P – M. The equations above are restricted to carbonate systems without other weak acids or bases….M Alkalinity and P Alkalinity.
| pure H2CO3 solution: | M alkalinity = 0 |
|---|---|
| pure Na2CO3 solution: | caustic alkalinity = 0 |
How do you calculate the alkalinity of caco3?
What is the difference between phenolphthalein alkalinity and total alkalinity?
Phenolphthalein alkalinity measures the hydroxides and half the carbonates at a pH 8.3. Total alkalinity measures all carbonate, bicarbonate, and hydroxide alkalinity at a pH 4.5 (approximately).
What does mg L as CaCO3 mean?
calcium carbonate
Both measurements (mg/l or KH) are usually expressed as mg/l CaCO. 3. – meaning the concentration of carbonate expressed as if calcium carbonate were the sole source of carbonate ions.
What colour does phenolphthalein go in alkaline and acid?
Indicators are substances that change colour when they are added to acidic or alkaline solutions. Litmus, phenolphthalein, and methyl orange are all indicators that are commonly used in the laboratory. Litmus indicator solution turns red in acidic solutions, blue in alkaline solutions, and purple in neutral solutions.
What is the pH of phenolphthalein?
Phenolphthalein, (C20H14O4), an organic compound of the phthalein family that is widely employed as an acid-base indicator. As an indicator of a solution’s pH, phenolphthalein is colourless below pH 8.5 and attains a pink to deep red hue above pH 9.0.
What is the formula for alkalinity?
Solving for alkalinity yields: Alk(meq/L)=3.9 meq/mL. To calculate alkalinity as calcium carbonate, use this formula to calculate the alkalinity in concentration of calcium carbonate (CaCO3). Insert the values into the formula to determine the alkalinity as CaCO3: Alk(mg/L as CaCO3)=(50044xBxCaxCF)÷Vs.
What is the relationship between alkalinity and pH?
A General Relationship Between Alkalinity and pH. As you will note, total alkalinity alone (i.e. bicarbonate alkalinity) does not produce a pH above 8.3. P alkalinity (carbonate alkalinity) is required to increase the pH above 8.3. At pH values above 10, caustic alkalinity is present.
