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When adding the aldehyde or ketone to Tollens' reagent, the test tube is put in a warm water bath. If the reactant under test is an aldehyde, Tollens' test results in a silver mirror. If the reactant is a ketone, it will not react because a ketone cannot be oxidized easily. A ketone has no available hydrogen atom on the carbonyl carbon that can be oxidized - unlike an aldehyde, which has this hydrogen atom.
Wiki User
∙ 12y ago
Wiki User
∙ 13y agoThe Tollens' reagent is meant to identify aldehyde compounds.
However, it also gives positive results for methanoic acid (formic acid) and alpha-hydroxy ketones.
So, if you were looking for an aldehyde, either of these compound types would give "false" positives.
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Why fructose gives positive tollen reagent test?
Only aldehydes give a positive Tollens test. However, under the strongly basic conditions of the test, alpha-hydroxy ketones can isomerize to aldehydes, so they will also give a positive Tollens test. Fructose is an alpha-hydroxy ketone.
Why does the formic acid give positive test with Tollens reagent?
The formic acid is special because doesn't contain an alkyl group but only an atom of hydrogen; so resembles to an aldehyde.
Is vanillin positive in tollens test?
No.While vanillin is an aldehyde, which should react with Tollens' reagent to precipitate silver metal, vanillin does not "pass" Tollens' test. Tollens' reagent is very basic (sodium or potassium hydroxide). Vanillin has a phenolic hydrogen (OH bonded to a phenyl ring) which is slightly acidic. Vanillin will react first with the excess hydroxide ions in solution to form a phenoxide salt, which will not participate in the silver-precipitating reaction.
Which halogens give a positive beilstein test?
which halogens give a positive beilstein test?
After hydrolysis did sucrose give a positive test with fehlings test why orwhy not?
After hydrolysis sucrose did give a positive test. It reduces sugar that has hemiketal and hemiaetal in it.
Why fructose gives positive tollen reagent test?
Only aldehydes give a positive Tollens test. However, under the strongly basic conditions of the test, alpha-hydroxy ketones can isomerize to aldehydes, so they will also give a positive Tollens test. Fructose is an alpha-hydroxy ketone.
Is fructose gives positive test with tollens reagent?
no negative
How is a positive tollens test recognised?
A silverish ppt. Called "silver mirror"
What is the principles of tollen's test?
The principle of Tollens' test is to distinguish between aldehydes and ketones. It involves the reduction of silver ions to silver metal in the presence of aldehydes, which results in the formation of a silver mirror on the inner surface of the test tube. Ketones do not give a positive Tollens' test because they do not undergo this reaction with silver ions.
Are substances that test positive with the Ames test necessarily carciongenic in humans?
The substances that are test positive with Ames test may or may not be carcinogenic for humans. Similarly, some substances that cause cancer in laboratory animals do not give a positive result Ames test. It is not possible to decide the carcinogenicity of any substances only depending on the Ames test.
Why does the formic acid give positive test with Tollens reagent?
The formic acid is special because doesn't contain an alkyl group but only an atom of hydrogen; so resembles to an aldehyde.
Is vanillin positive in tollens test?
No.While vanillin is an aldehyde, which should react with Tollens' reagent to precipitate silver metal, vanillin does not "pass" Tollens' test. Tollens' reagent is very basic (sodium or potassium hydroxide). Vanillin has a phenolic hydrogen (OH bonded to a phenyl ring) which is slightly acidic. Vanillin will react first with the excess hydroxide ions in solution to form a phenoxide salt, which will not participate in the silver-precipitating reaction.
Which test substances did not test positive for any of the organic compounds?
DNA
Do Hydrocodone and Morphine give the same results on an urine test?
Yes the two substances will indicate a positive result for opioid ingestion.
Which halogens give a positive beilstein test?
which halogens give a positive beilstein test?
Did gelatin give positive result with xanthoprotic test?
yes,it give positive test
Can Hydoxycut give you a false positive tast?
Hydroxycut cannot give you a false positive on a drug test, the same goes for pregnancy tests. Each test tests for particular drugs or compounds that would indicate whether the person taking the test has taken any illegal substances or is in fact pregnant.
