Question

В четырех пронумерованных склянках находятся растворы: гидроксида натрия, хлорида натрия, соляной кислоты и фенолфталеина. Как определить, в какой склянке какое вещество находится, не используя дополнительных реактивов, но имея достаточное количество пустых пробирок. Напишите уравнения проведенных реакций.

Answer 1

При взаимодествии щелочи с кислотой выпадает осадок выделяется вода:NaOH+HCl=NaCl+H2O ; фенолфталеин на NaCl дает бесцветный окрас(нейтральная ср.),на кислоту HCl бесцветный,на щелоч малиновый. Отличие между кислотой и каменной солью даст образовавшийся осадок

Answer 2

Identifying the Substances in the Glassware

To determine which substance is in each glassware without using additional reagents, you can perform simple tests based on the properties of the substances. Here's how you can identify each substance:

1. Sodium Hydroxide (NaOH): - Sodium hydroxide is a strong base that reacts with acids to form salts and water. - Take a small amount of the solution from one of the glassware and add a few drops of vinegar (acetic acid) to it. - If the solution turns into a milky white color or forms a white precipitate, it indicates the presence of sodium hydroxide. - The reaction can be represented by the following equation: NaOH + CH3COOH → CH3COONa + H2O.

2. Sodium Chloride (NaCl): - Sodium chloride is a common salt that is soluble in water and does not react with vinegar or other common acids. - Take a small amount of the solution from another glassware and add a few drops of vinegar to it. - If there is no visible reaction or change in the solution, it indicates the presence of sodium chloride. - The equation for the reaction between sodium chloride and vinegar is: NaCl + CH3COOH → No reaction.

3. Hydrochloric Acid (HCl): - Hydrochloric acid is a strong acid that reacts with bases to form salts and water. - Take a small amount of the solution from a different glassware and add a few drops of baking soda (sodium bicarbonate) to it. - If the solution produces effervescence (bubbling) or releases carbon dioxide gas, it indicates the presence of hydrochloric acid. - The reaction can be represented by the following equation: HCl + NaHCO3 → NaCl + H2O + CO2.

4. Phenolphthalein: - Phenolphthalein is a pH indicator that is colorless in acidic solutions and turns pink or red in basic solutions. - Take a small amount of the solution from the remaining glassware and add a few drops of water to it. - If the solution turns pink or red, it indicates the presence of phenolphthalein. - The reaction between phenolphthalein and water is not a chemical reaction but a change in color due to the pH level.

Please note that these tests are based on the properties of the substances and may not be definitive. It is always recommended to use proper laboratory techniques and reagents for accurate identification.