Question

B чотирьох пробірках знаходяться порошки купрум(ІІ) оксиду, ферум(ІІІ) оксиду, срібла, заліза. Як розпізнати ці речовини, використовуючи тільки один хімічний реактив?

Answer 1

При розчиненні оксиду міді в соляній кислоті утворюється зелений розчин
2HCl + CuO = CuCl₂ + H₂O
СuCl₂ + 2HCl = H₂[CuCl₄]

при розчиненні оксиду заліза в соляній кислоті утворюється коричневий розчин
6HCl + Fe₂O₃ = 2FeCl₃ + 3H₂O

реакція не йде
HCl + Ag ≠

на поверхні заліза виділяються бульбашки газу
2HCl + Fe = FeCl₂ + H₂↑

Answer 2

Identifying the Substances in the Test Tubes

To identify the substances in the four test tubes (containing copper(II) oxide, iron(III) oxide, silver, and iron powders), we can use a single chemical reagent. Here's a step-by-step approach to identifying each substance:

1. Copper(II) Oxide: Copper(II) oxide can be identified by its reaction with hydrochloric acid (HCl). When copper(II) oxide reacts with HCl, it forms copper(II) chloride and water. The reaction can be represented as follows:

Copper(II) oxide + Hydrochloric acid → Copper(II) chloride + Water

The formation of a blue-green solution indicates the presence of copper(II) oxide.

2. Iron(III) Oxide: Iron(III) oxide can be identified by its reaction with a reducing agent, such as hydrogen gas (H2). When iron(III) oxide reacts with hydrogen gas, it forms iron metal and water. The reaction can be represented as follows:

Iron(III) oxide + Hydrogen gas → Iron + Water

The formation of iron metal (which appears as a black precipitate) indicates the presence of iron(III) oxide.

3. Silver: Silver can be identified by its reaction with concentrated nitric acid (HNO3). When silver reacts with nitric acid, it forms silver nitrate and nitrogen dioxide gas. The reaction can be represented as follows:

Silver + Nitric acid → Silver nitrate + Nitrogen dioxide

The formation of a white precipitate (silver nitrate) indicates the presence of silver.

4. Iron: Iron can be identified by its reaction with a solution of potassium hexacyanoferrate(III) (also known as potassium ferricyanide). When iron reacts with potassium ferricyanide, it forms a dark blue precipitate called Prussian blue. The reaction can be represented as follows:

Iron + Potassium ferricyanide → Prussian blue

The formation of a dark blue precipitate indicates the presence of iron.

By performing these reactions with the given substances, you can identify each substance based on the observed color changes and precipitate formations.

Note: It is important to handle chemicals safely and follow proper laboratory procedures when conducting chemical reactions.