0
Want this question answered?
Be notified when an answer is posted
Add your answer:
Earn +20 pts
Why is a back titration sometimes used for an analysis rather than a direct titration?
Back titrations are used when a reaction occurring in the conical flask can not be detected using an indicator such as phenolphthalein. So, after this titration has been performed, the 'excess' is then titrated with something that can be detected more easily using phenolphthalein etc.
Why you use oxalate potassium in formol titration?
In formol titration, amino acids with formaldehyde are titrated with NaOH to measure the amount of amino acids in the solution. Potassium is also necessary for this titration and is supplied by using potassium oxalate. If calcium is present, it will react with the NaOH to form Ca(OH)2. This will make it appear to need more of the NaOH solution (and overestimate the titration). Potassium oxalate will chelate the calcium, and prevent it from reacting (forming calcium oxalate).
Which is more polar bromophenol blue or phenolphthalein?
phenolphthalein
What would happen if you added phenolphthalein to sodium hydroxide?
Phenolphthalein is the indicator to see if it is more acidic or more basic
How would your results have differed if you had over titrated added Na OH beyond the endpoint?
Due to the addition of more NaOH than was necessary to reach the endpoint of the titration, the recorded data would show NaOH at a higher concentration, and whatever other chemical in solution (the analyte of the titration) to appear at a lower concentration. If recording the amount of mL of the titrant added to the analyte to reach the end-point of the titration, it would cause the recorded mL needed to be higher than the true amount needed.
Why is a back titration sometimes used for an analysis rather than a direct titration?
Back titrations are used when a reaction occurring in the conical flask can not be detected using an indicator such as phenolphthalein. So, after this titration has been performed, the 'excess' is then titrated with something that can be detected more easily using phenolphthalein etc.
What will happen to the molarity of NaOH If a drop of NaOH falls out of the flask during the titration?
You have to realise that a drop from the burette for instance is insignificant, if you are dealing with at least 10ml solution which you usually deal with on a titration. If you don't want to regard it as insignificant, then if NaOH is in the burette, then the solution doesn't become more concentrated with NaOH because that drop escaped.
Why you use oxalate potassium in formol titration?
In formol titration, amino acids with formaldehyde are titrated with NaOH to measure the amount of amino acids in the solution. Potassium is also necessary for this titration and is supplied by using potassium oxalate. If calcium is present, it will react with the NaOH to form Ca(OH)2. This will make it appear to need more of the NaOH solution (and overestimate the titration). Potassium oxalate will chelate the calcium, and prevent it from reacting (forming calcium oxalate).
Why is titration method applicable in aspirin analysis?
When I am using back titration and direct titration as my two methods for determining the purity of aspirin tablets. doesn't the direct titration not take into consideration of the excess sodium hydroxide added to the aspirin?In both these titrations when I reach the end-point it turns pink but I kept these solution the next day and they turned back to colourless. Is this meant to happen and what chemical reaction has happened here?I titrated this again with more sodium hydroxide till the end-point then added this to the overall amount of NaOH i added in the flask.Is the only difference between back titration and direct titration not addding the HCl at the end to determine the excess amount of NaOH?Are there any methods for direct titration.Would really appreciate any help.The best you can obtain is an end point lasting 20-30 seconds. Any excess base will slowly hydrolyze the ester and liberate acetate ion from the act's because aspirin is such a weak acid that it reacts slowly with the NaOH, making it difficult to accurately get a good endpoint in a reasonable time.With back titration, you react with an excess of NaOH (known amount), heat it to make the reaction go to completion quickly, then use HCl to determine the amount of NaOH that is remaining. This reaction will go quickly, and is much easier to measure.elylsalicylic acid,aspirin.
Which is more polar bromophenol blue or phenolphthalein?
phenolphthalein
What would happen if you added phenolphthalein to sodium hydroxide?
Phenolphthalein is the indicator to see if it is more acidic or more basic
How would your results have differed if you had over titrated added Na OH beyond the endpoint?
Due to the addition of more NaOH than was necessary to reach the endpoint of the titration, the recorded data would show NaOH at a higher concentration, and whatever other chemical in solution (the analyte of the titration) to appear at a lower concentration. If recording the amount of mL of the titrant added to the analyte to reach the end-point of the titration, it would cause the recorded mL needed to be higher than the true amount needed.
Why should the endpoint be taken as the faint pink color of the indicator?
When using an indicator in a titration, the color changes happen when the titrant has reacted with all the substance of interest in the sample. As soon as the titrant isn't reacting with the sample any more, it starts reacting with the indicator, and continuing past the first hint of color will be using too much titrant, and the calculations for the concentration of the sample will be wrong. Phenolphthalein starts out pink, but will turn red as the pH keeps changing as you go further past the endpoint of the titration.
Is the universal indicator or phenolphthalein is more accurate?
THe universal indicator is more accurate as it can detect different ranges in the pH, whereas phenolphthalein only changes at a ph of 8.0
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 do you titrate strong base against weak acid using phenolphthalein?
A strong base and weak acid gives a basic salt. Therefore the end point of a titration between a strong base and a weak base has a pH value above than 7.0 at 298K. As the end point of phenolphthalein is around 9.1 (~can vary between the values of 8.1 to 10.1) at this temperature, it would give more accurate results.
When phenolphthalein is added to ammonium hydroxide is the color of the final solution is pink?
Phenolphthalein is an indicator often used in chemical titrations. Phenolphthalein is colorless in acidic solutions and turns pink in basic solutions. The more basic the solution the pinker the solution will become when Phenolphthalein is present.
