1. Definition of Hf

Hf or Hafnium is an element with the symbol Hf and atomic number 72 in the periodic table. Its English name is also Hafnium. The atomic mass of Hf is 178.49 and the atomic weight is 72. Hafnium molecules usually consist of one Hf atom. Under standard conditions, Hf does not form ions.

2. Properties of Hf

2.1 Physical properties of Hf
Hafnium is a silver-colored metal with a solid state at room temperature. It does not have a smell and does not have a pH level because it is a metal and does not dissolve in water.

2.2 Chemical properties of Hf
Hafnium mainly reacts to form compounds with sulfur, carbon, nitrogen, and halogens. Hf can also react with oxygen to form HfO₂.

3. Common chemical equations of Hf
   As Hf is a metal, it can participate in reactions such as:
   Hf + O₂ -> HfO₂
   Hf + 2H₂ -> HfH₂
   Hf + 2S -> HfS₂

4. Preparation of Hf

4.1 Laboratory preparation of Hf
Hafnium is typically not prepared in the laboratory because the process is quite complicated and requires specialized equipment.

4.2 Industrial preparation of Hf
In industry, Hafnium is typically extracted from zirconium minerals such as zircon and baddeleyite. This process involves separating zirconium and hafnium using organic solvents and acids.

1. HF is a colorless liquid, with an unpleasant odor, and very toxic. HF is known as hydrofluoric acid, the English name is Hydrofluoric Acid. HF consists of one hydrogen atom and one fluorine atom, the atomic mass of hydrogen is 1 and fluorine is 19, so the atomic mass of HF is 20. In chemistry, HF can also form HF- ion when losing an electron.

2. Properties: HF

2.1 The state of HF at normal temperature is a colorless liquid, with an unpleasant odor. The pH of HF is 3.17 at a temperature of 25 degrees C, this is a strong acid.

2.2 HF has the ability to react with many substances. HF is very strong and can corrode glass.

3. Chemical equation

HF reacts with metal (such as Na, K) to form salts and hydrogen gas.
HF + Na -> NaF + H₂

HF can also react with a stronger acid (such as H₂SO₄) to produce F₂ gas.
2HF + H₂SO₄ -> 2H₂O + SO₂ + F₂

3. Preparation of HF

HF can be prepared by reacting fluorine with water:
F₂ + 2H₂O -> 2HF + O₂

On an industrial scale, HF is usually produced by dissolving fluorite (CaF₂) in sulfuric acid (H₂SO₄) at high temperatures.