Question

В двух неподписанных пробирках находятся хлориды двух- и трехвалентного железа. Учащимся нужно различить эти вещества. Света предложила использовать раствор угольной кислоты. Артем сказал, что это не поможет, и нужно взять раствор гидроксида натрия . Кто из ребят оказался прав и взял нужный реактив для доказательства? Приведи аргументы, подтверждающие ответ. Опиши наблюдения в ходе опыта.

Answer 1

Прав -Артем. 
 так как соли железа II и III с гидроксидом натрия дают осадки разных цветов.
Двухвалентное железо - Fe(OH)2    гидроксид железа II - осадок болотного ( зеленого цвета)
FeCl2  + 2NaOH   => Fe(OH)2  + 2NaCl

Трехвалентное железо  - Fe(OH)3   гидроксид железа III - осадок хлопьевидный, коричневого ( ржавого) цвета  
FeCl3  + 3NaOH   => Fe(OH)3  + 3NaCl

Answer 2

The Experiment to Differentiate Iron Chlorides

To differentiate between the iron chlorides in the two unmarked test tubes, Sveta suggested using a solution of carbonic acid (carbon dioxide dissolved in water), while Artem argued that a solution of sodium hydroxide would be more effective. Let's explore the arguments and observations to determine who made the correct choice.

Sveta's Argument: Using Carbonic Acid Solution

Sveta proposed using a solution of carbonic acid to differentiate the iron chlorides. Carbonic acid is a weak acid formed when carbon dioxide dissolves in water. She likely based her suggestion on the fact that carbonic acid can react with certain metal ions, including iron, to form insoluble carbonates. By adding carbonic acid to the test tubes, Sveta may have expected to observe the formation of precipitates, which could help identify the iron chlorides.

Artem's Argument: Using Sodium Hydroxide Solution

Artem, on the other hand, argued that a solution of sodium hydroxide (NaOH) would be more suitable for differentiating the iron chlorides. Sodium hydroxide is a strong base that can react with metal ions, including iron, to form insoluble hydroxides. Artem likely believed that adding sodium hydroxide to the test tubes would result in the formation of precipitates, allowing for the identification of the iron chlorides.

Observations during the Experiment

To determine who made the correct choice, we need to consider the observations made during the experiment. Here are the possible outcomes and their implications:

1. Formation of a Precipitate with Carbonic Acid Solution: If a precipitate forms when carbonic acid is added to one of the test tubes, it would indicate the presence of a carbonate, suggesting the presence of a three-valent iron chloride. This would support Sveta's argument.

2. Formation of a Precipitate with Sodium Hydroxide Solution: If a precipitate forms when sodium hydroxide is added to one of the test tubes, it would indicate the presence of a hydroxide, suggesting the presence of a two-valent iron chloride. This would support Artem's argument.

3. No Precipitate Formation: If no precipitate forms with either carbonic acid or sodium hydroxide, it would suggest that neither test tube contains iron chlorides. In this case, both Sveta and Artem would be incorrect, and further tests may be required to identify the substances in the test tubes.

To determine the correct answer, it would be necessary to conduct the experiment and observe the reactions between the test tubes and the respective reagents. The presence or absence of precipitates would provide valuable information for identifying the iron chlorides.

Please note that without conducting the experiment and observing the reactions, it is not possible to definitively determine who made the correct choice. The arguments presented by Sveta and Artem are based on their understanding of the reactivity of iron chlorides with carbonic acid and sodium hydroxide, respectively.