First, make sure that the test solution is acid. The most basic method to achieve the goal - to use the indicator. For example, litmus and methyl orange in acidic environment will turn red, the phenolphthalein will remain white.
Next, examine what is available to your look. Hydrochloric acid fumes (there is light white smoke, similar to steam), particularly in the humid air. Looking closely, you will definitely notice this property. Just do not forget about caution, or risk getting a burn on the skin, mucous membranes or respiratory tract. In addition, this compound has a sharp unpleasant odor. But if you decide to use such a sign, be sure to observe the safety precautions (careful strokes the palm direct the air to himself, not stoop to the container and do not inhale deeply).
Then take a small glass (subject) and place two drops of one of the studied acid and the other ammonia solution (ammonia). If the acid salt, there will be white smoke (hydrochloric acid in the amount of one drop to soar). Following reaction takes place with the formation of ammonium chloride: NH3 + HCl → NH4Cl.
You can also use another chemical property. To carry out the reaction of interaction with strong oxidizing agents (potassium permanganate, manganese dioxide), which is accompanied by release of chlorine gas: 2KMnO4 + 16HCl → 5Cl2↑ + 2MnCl2 + 2KCl + 8H2O. A slight odor of chlorine will help you to determine.
Use the demonstration method is the reaction with silver nitrate. The tube containing the unknown acid add 2-3 drops of silver nitrate (AgNO3 leaves the skin with black spots, so work better with gloves). The appearance of a white precipitate, resembling cottage cheese, will clearly indicate the presence of chloride ion. The reaction proceeds as follows: AgNO3 + HCl = AgCl ↓ (cheesy white precipitate) + HNO3. After some time, the sediment hardens, forming plaque on the walls of the tube.
Advice 2: How to recognize acetic acid
Acetic acid - an indispensable thing in the kitchen. It is used in everyday cooking and for marinades and other delicious things. Some women use it to cleanse the instrument from scale and other economic purposes. To recognize acetic acid is very simple, and to mix it does not work.
Smell - the characteristic difference of acetic acid. It is very sharp and Shiba nose. Don't sniff the bottle with a concentrated vinegar close, bring it in 10-15 cm from the nose. If you are close you can smell fumes coming from the liquid, can burn the respiratory tract and problems will be very much. Try not to drip and the skin will burn.
Acetic acid burn. Pour some liquid into a little bowl and put a match, but be careful you can get burned. Combustion is about the same as the regular alcohol. As it evaporates it ceases. If ignition did not happen, you have either Apple cider vinegar or some other liquid or dilute acid.
Distinctive sour taste speaks for itself. But don't try acid directly from the bottle, you can get severe burns of the esophagus. Pour a teaspoon into a glass and dilute at least 20 parts clean water. Then can try, you should feel the sour taste and sharp smell. In diluted form it is used for making various sauces.
Unfortunately, the home does not carry out any experiments for a more precise definition of the substance. Therefore, other experiments leave for professional technicians. And, of course, do not drink the substance inside if you are in doubt. Acetic acid is very cheap, so better buy a new one than you'd get poisoned unknown composition.