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Why methyl orange alkalinity equal to total alkalinity?
Alkalinity is different from basicity, which is directly related to the pH. The higher the pH, the more basic the water.Like acidity, there are different ways to measure and report alkalinity;The first is to titrate the water with acid titrant to the phenolphthalein end point. This is called the phenolphthalein alkalinity. Since phenolphthalein changes color at pH~8.3, this corresponds to a pH where all the CO32- present would be protonated.Second, acid titration to a methyl orange end point, pH~4.3, further converts the bicarbonate to aqueous carbon dioxide. At this end point, some of the weaker conjugate bases are protonated. The methyl orange end point titration indicates total alkalinity.
Why phenol phethaline alkalinity equal to half alkalinity?
Phenolphthalein alkalinity is considered to be half of the total alkalinity because it specifically measures the concentration of hydroxide ions (OH⁻) and bicarbonate ions (HCO₃⁻) in a solution, which are responsible for the initial buffering capacity. Total alkalinity encompasses all buffering species, including carbonate ions (CO₃²⁻) and other forms of alkalinity that contribute to the system's ability to resist pH changes. Since phenolphthalein only accounts for the species that neutralize strong acids to a pH of around 8.3, it typically reflects only a portion of the total alkalinity, hence the halving effect. This distinction is important in understanding the chemical equilibria in aquatic systems and in water quality assessments.
Why the water sample remains colorless or change to pink upon addition of phenolpthalein indiactor in total alkanilty expt?
In a total alkalinity experiment, the water sample may remain colorless or change to pink upon the addition of phenolphthalein indicator based on the pH of the water sample. If the water sample is acidic (pH below 8.3), phenolphthalein will remain colorless. If the water sample is basic (pH above 8.3), phenolphthalein will turn pink due to the presence of hydroxide ions, indicating the total alkalinity of the water.
Is phenolphthalein a compound?
Yes, phenolphthalein is a compound with the molecular formula C20H14O4.
Why is phenolphthalein indicator used?
Phenolphthalein is used as an indicator because the color of the solution is changed according to pH.
Difference between phenolphthalein alkalinity and and total alkalinity?
Phenolphthalein alkalinity measures the hydroxide ion concentration in water, specifically the amount that can be neutralized by strong acids. Total alkalinity, however, measures the water's ability to neutralize acids, including carbonate, bicarbonate, and hydroxide ions. In summary, phenolphthalein alkalinity focuses on the hydroxide ions, while total alkalinity considers a broader range of alkaline substances.
What is phenolphthalein indicator used for in chemical experiments?
Phenolphthalein indicator is used in chemical experiments to determine the acidity or alkalinity of a solution by changing color based on the pH level.
Why methyl orange alkalinity equal to total alkalinity?
Alkalinity is different from basicity, which is directly related to the pH. The higher the pH, the more basic the water.Like acidity, there are different ways to measure and report alkalinity;The first is to titrate the water with acid titrant to the phenolphthalein end point. This is called the phenolphthalein alkalinity. Since phenolphthalein changes color at pH~8.3, this corresponds to a pH where all the CO32- present would be protonated.Second, acid titration to a methyl orange end point, pH~4.3, further converts the bicarbonate to aqueous carbon dioxide. At this end point, some of the weaker conjugate bases are protonated. The methyl orange end point titration indicates total alkalinity.
What happen when phenopthelein is added to acid?
Phenolphthalein is colorless in acidic solutions and will remain colorless when added to an acid. This is because phenolphthalein changes color at a pH of around 8.2 to 10, indicating alkalinity.
Which indicators are used for alkalinity titration?
The indicators commonly used for alkalinity titration include phenolphthalein and bromcresol green. Phenolphthalein turns pink in the presence of excess base (at a pH greater than 8.2), while bromcresol green changes color from yellow to blue in the pH range of 3.8 to 5.4, indicating the endpoint of the titration.
What is p alkanity stands for?
P alkalinity, or phenolphthalein alkalinity, refers to the concentration of bicarbonate and carbonate ions in water, measured using phenolphthalein as an indicator. It is a key parameter in assessing water quality, particularly in freshwater systems, and indicates the water's ability to neutralize acids. P alkalinity is typically determined by titrating a water sample with a strong acid until a color change occurs, reflecting the endpoint of alkalinity. It helps in understanding the buffering capacity of water, which is crucial for aquatic life and ecosystem health.
Why is phenolphthalein used as an indicator in chemical experiments?
Phenolphthalein is used as an indicator in chemical experiments because it changes color depending on the acidity or alkalinity of a solution. This makes it easy to visually determine the endpoint of a reaction or the pH level of a solution.
Why phenol phethaline alkalinity equal to half alkalinity?
Phenolphthalein alkalinity is considered to be half of the total alkalinity because it specifically measures the concentration of hydroxide ions (OH⁻) and bicarbonate ions (HCO₃⁻) in a solution, which are responsible for the initial buffering capacity. Total alkalinity encompasses all buffering species, including carbonate ions (CO₃²⁻) and other forms of alkalinity that contribute to the system's ability to resist pH changes. Since phenolphthalein only accounts for the species that neutralize strong acids to a pH of around 8.3, it typically reflects only a portion of the total alkalinity, hence the halving effect. This distinction is important in understanding the chemical equilibria in aquatic systems and in water quality assessments.
Does sodium carbonate react with phenolphthalein indicator?
Sodium carbonate does react with phenolphthalein indicator, producing a color change from colorless to pink in alkaline solutions. Sodium carbonate is a common base that can be used to test for the presence of acidity or alkalinity in a solution using phenolphthalein.
Why double indicator is used during the titration of water to find alkalinity of water sample?
Double indicator (phenolphthalein and methyl orange) is used during the titration of water to find the alkalinity of the water sample because each indicator changes color at different pH ranges. Phenolphthalein changes color in the alkaline pH range, indicating the endpoint of the titration for total alkalinity. Methyl orange changes color in the acidic pH range, aiding in the detection of the endpoint for carbonate alkalinity. Using both indicators helps to accurately determine the different forms of alkalinity present in the water sample.
How phenolphthalein work in an alkali?
Phenolphthalein is a pH indicator that changes color based on the acidity or alkalinity of a solution. In an alkaline environment (pH above 8.2), phenolphthalein turns from colorless to pink due to the deprotonation of its phenolic hydrogen, resulting in a negatively charged ion that absorbs light differently. This color change indicates the presence of a basic solution, making phenolphthalein useful for titrations and pH testing.
Why the water sample remains colorless or change to pink upon addition of phenolpthalein indiactor in total alkanilty expt?
In a total alkalinity experiment, the water sample may remain colorless or change to pink upon the addition of phenolphthalein indicator based on the pH of the water sample. If the water sample is acidic (pH below 8.3), phenolphthalein will remain colorless. If the water sample is basic (pH above 8.3), phenolphthalein will turn pink due to the presence of hydroxide ions, indicating the total alkalinity of the water.
