After some considerable time trying to get a really really extraordinarily spankingly amazingly clean piece of glassware we finally made this silver mirror appear on this conical flask.
To carry out the tollens test for an aldehyde a a test tube was rigorously cleaned with concentrated KOH (Potassium Hydroxide)
To form the tollens reagent a fingers depth of Silver Nitrate Solution 0.05n was added. To this ammonia solution was added which formed a white suspension, ammonia solution was added until the white precipitate had just disappeared. (Once the tollens solution is completed it must be used within a few hours or explosive silver nitrite may form)
To test for an aldehyde a few drops of aldehyde are added to the solution and the test tube heated in a warm water bath for around 5 minutes.
If an aldehyde is present a silver mirror will form on the glass. (if the glassware is not absolutely perfectly clean a dark precipitate may appear in the solution instead)