If the carbonate ion is only responsible for the alkalinity, thena.The phenolphthalein alkalinity would be greater than half of the methyl orange alkalinityb.The phenolphthalein alkalinity would be equal to half of the methyl orange alkalinityc.The phenolphthalein alkalinity would be equal to the methyl orange alkalinityd.The phenolphthalein alkalinity would be lower than half of the methyl orange alkalinityClear my choice
Question
If the carbonate ion is only responsible for the alkalinity, thena.The phenolphthalein alkalinity would be greater than half of the methyl orange alkalinityb.The phenolphthalein alkalinity would be equal to half of the methyl orange alkalinityc.The phenolphthalein alkalinity would be equal to the methyl orange alkalinityd.The phenolphthalein alkalinity would be lower than half of the methyl orange alkalinityClear my choice
Solution
The correct answer is b. The phenolphthalein alkalinity would be equal to half of the methyl orange alkalinity.
Here's why:
Alkalinity is a measure of the ability of a solution to neutralize acid without changing the pH significantly. It is usually expressed in terms of equivalent concentration of calcium carbonate (CaCO3).
Phenolphthalein alkalinity and methyl orange alkalinity are two methods used to measure alkalinity, and they are named after the indicators used in the titration process.
Phenolphthalein changes color at a pH of 8.3, and methyl orange changes color at a pH of 4.3. Therefore, phenolphthalein alkalinity measures the amount of alkalinity up to a pH of 8.3, and methyl orange alkalinity measures the amount of alkalinity up to a pH of 4.3.
If the carbonate ion (CO3^2-) is the only species responsible for the alkalinity, then the phenolphthalein alkalinity would be equal to half of the methyl orange alkalinity. This is because one mole of carbonate ion can neutralize two moles of acid to reach a pH of 4.3 (methyl orange endpoint), but it can only neutralize one mole of acid to reach a pH of 8.3 (phenolphthalein endpoint). Therefore, the phenolphthalein alkalinity (which measures the ability to neutralize one mole of acid) would be half of the methyl orange alkalinity (which measures the ability to neutralize two moles of acid).
Similar Questions
If the phenolphthalein alkalinity is equal to the total alkalinity then what would be the reason behind alkalinity?a.Bicarbonate ions onlyb.Carbonate ions onlyc.Both, hydroxide and carbonate ionsd.Hydroxide ions onlyClear my choice
If a solution of pure water and sodium hydroxide is titrated with H2SO4 for the alkalinity measurement. Then the correct option would be...a.The Phenolphthalein alkalinity will be the total alkalinityb.The Phenolphthalein alkalinity will be the bicarbonate alkalinityc.The Methyl orange alkalinity will be the total alkalinityd.The Phenolphthalein alkalinity will not be the total alkalinity
A water sample was alkaline to both phenolphthalein and methyl orange. 50 mL of the watersample required 18 mL of 0.02 N H2SO4 for phenolphthalein end point and another 6 mLfor complete neutralisation. Describe the type and amount of alkalinity present.a.Alkalinity due to OH– = 24 ppm, Alkalinity due to CO32– = 24 ppmb.Alkalinity due to OH– = 240 ppm, Alkalinity due to CO32– = 240 ppmc.Alkalinity due to OH– = 340 ppm, Alkalinity due to CO32– = 140 ppmd.Alkalinity due to OH– = 00 ppm, Alkalinity due to CO32– = 480 ppmClear my choice
100 mL of a raw water sample required 25 mL of N/50 H2SO4 for neutralisation to phenolphthalein end point. After this methyl orange indicator was added to it and the end point was 28.0 mL. Calculate the alkalinity of water as CaCO3 equvivalents in parts per million.a.Alkalinity due to HCO32– = 60ppm Alkalinity due to CO32– = 220 ppmb.Alkalinity due to OH– = 220 ppm Alkalinity due to CO32– = 60 ppmc.Alkalinity due to HCO32– = 220 ppm Alkalinity due to CO32– = 60 ppmd.Alkalinity due to OH– =60 ppm Alkalinity due to CO32– =220 ppm
100 ml of an alkaline water in presence of phenolphthalein, 50 ml of the N/100 HCl. The resulting mixture in presence of methyl orange indicator consumes 35 ml of HCl. Predict the alkalinities and calculate their amounts in ppm as CaCO3 equivalent.
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