How to distinguish solutions in test tubes

How to distinguish solutions in test tubes

Sometimes, owing to the arisen circumstances, it is necessary to distinguish solutions in test tubes, and on appearance absolutely identical. For example, it can be practical work, laboratory trial or usual curiosity. How to define substances, using the minimum quantity of reactants? It is enough to apply some knowledge in the field of chemistry and, unsolvable at first sight, the riddle will lose interest.

It is required to you

  • Test tubes, hydrochloric acid, sodium hydroxide, ammonium chloride, silver nitrate, phenolphthalein, methyl orange


1. For example, three test tubes in which are are given: hydrochloric acid, sodium hydroxide and chloride of ammonium. All solutions of the presented substances are visually identical – without color and flavourless. It is possible to begin the analysis of the offered substances.

2. At first for definition of chemical compounds use paper indicators or their solutions. For this purpose in all three test tubes lower or flow the fenolftaleinovy indicator. In that test tube in which it crimson it will become possible to state availability of alkali, that is sodium hydroxide.

3. It can be explained with the fact that the alkaline environment formed for the account hydroxide of ions changes color of the indicator, changing a colourless reactant for crimson coloring. Thus, one substance is defined, and therefore exclude it from a set of the studied substances.

4. In the remained two test tubes lower or flow litmus or methyl orange (methyl orange). In one of test tubes the methyl orange which originally have orange color will become red. It can demonstrate to presence at an acid test tube as ions of hydrogen promote change of coloring of a reactant. Means and the second substance underwent definition.

5. The third chemical compound is admissible to define by process of elimination, that is, in the remained test tube there is an ammonium chloride. However it is possible to carry out more exact analysis and to confirm the assumptions. For this purpose divide test tube contents into two parts and analyze each of them.

6. Add solution of sodium hydroxide to one part and practically the specific smell of liquid ammonia which is used at consciousness loss will be felt at once. The smell appears as as a result of reaction of salt of ammonium decay alkalis to the ammonia representing flying gaseous substance with "aroma" of urea.

7. As chloride of ammonium incorporates also chloride ions, carry out high-quality reaction to their existence. For this purpose add to the second part of estimated chloride of ammonium reagent silver nitrate, and as a result of chemical interaction the white deposit of chloride of silver will drop out. It is also confirmation of presence of ions of chlorine. Thus, using simple skills and abilities and also the simplest reactants, it is possible to distinguish the solutions in test tubes offered for a research.

Author: «MirrorInfo» Dream Team