Selenic Acid consists of the elements Hydrogen, Selenium, and Oxygen. Hydrogen is non-toxic, odorless, colorless, and tasteless gas. It is the lightest element. Its atomic number is 1, and is present in group-1 of the periodic table. Hydrogen is represented with symbol H. Selenium is a rare nonmetal present in the group-16 of the periodic table. Its atomic number is 34 and is represented by the symbol Se. Oxygen is a highly reactive nonmetal present in group-16 of the periodic table. Its atomic number is 8 and is represented with the symbol O.
Selenic Acid Formula
Selenic acid is a crystalline, colorless, and strong soluble dibasic acid. The chemical formula of Selenic acid is H2SeO4. It is a selenium oxoacid whose structure is more precisely characterized as (HO)2SeO2. It is manufactured by oxidizing selenium compounds in lower oxidation states. One such method includes oxidizing selenium dioxide (SeO2) with hydrogen peroxide (H2O2).
Preparation of Selenic Acid
- One way of preparing selenic acid is by oxidizing lower oxidation state selenium compounds. Selenic Acid is prepared by the oxidation of Selenium Dioxide with Hydrogen Peroxide.
SeO2 + H2O2 ⇢ H2SeO4
- Another way of preparing selenic acid is using chlorine or bromine to oxidize the element selenium in a water suspension. It also gives hydrochloric or hydrobromic acid as a by product.
Se + 4H2O + 3Cl2 ⇢ H2SeO4 + 6HCl
Se + 4H2O + 3Br2 ⇢ H2SeO4 + 6HBr
Structure of Selenic Acid
Selenic Acid Structure
Physical Properties of Selenic Acid
- The appearance of Selenic Acid is a colorless crystalline form.
- Molecular weight of Selenic Acid is 144.9734 g/mol.
- The melting point of Selenic acid is 58°C.
- Its Boiling point is 260°C.
- The density of Selenic Acid is 2.95 g/cm3.
Chemical Properties of Selenic Acid
- Selenic Acid (H2SeO4) reacts with Fluorosulfuric acid (HO3SF) to give selenoyl fluoride (SeO2F2) and sulfuric acid (H2SO4).
H2SeO4 + 2HO3SF ⇢ SeO2F2 + 2H2SO4
- H2SeO4 reacts with Barium ions to form Barium Selenate (BaSeO4).
- Selenic Acid reacts with Gold to form a red-yellow solution of gold(III) selenate. Its chemical reaction of it is given below-
2Au + 6H2SeO4 → Au2(SeO4)3 + 3H2SeO3 + 3H2O
- Selenic Acid is soluble in water.
Uses of Selenic Acid
- Selenic Acid is used as an oxidizing agent.
- It is used in toilet cleaners, metal and drain cleaners.
- Selenic acid is used as rust removal compound.
- It is used in manufacturing fertilizers and refining metals.
Sample Questions
Question 1: What is the anion formed from the Selenic Acid?
Answer:
From Selenic Acid (H2SeO4), Selenate ion is formed as anion. The chemical formula of Selenate ion is SeO2-4. It is a strong oxidizer and soluble in aqueous solution at room temperature.
Question 2: Find the molar mass of Selenic Acid.
Answer:
Selenic Acid consists of 2 Hydrogens, 1 Selenium and 4 Oxygens.
Atomic weight of each Hydrogen atom = 1.00784
Atomic weight of Selenium = 78.96
Atomic Weight of each Oxygen atom = 15.999
Molar mass of H2SeO4 = (2 × 1.00784) + 78.96 + (4 × 15.999)
= 144.97
Question 3: What is the pH of selenic acid?
Answer:
As the name of compound specifies the pH must be less than 7, because for any acid, the pH value lies between 0-7. The pH value for the selenic acid is 2.74.
Question 4: Does Selenic Acid dissolve gold?
Answer:
Yes. Selenic Acid dissolve gold to form a red-yellow solution of gold(III) selenate (Au2(SeO4)3). The chemical reaction of it is given below,
2Au + 6H2SeO4 → Au2(SeO4)3 + 3H2SeO3 + 3H2O
Question 5: Is Selenic Acid Hazardous to health?
Answer:
Yes. Selenic Acid is hazardous to health. When selenic acid comes in contact it irritate and burn the skin and eyes. On breathing Selenic Acid can irritate the nose, throat and lungs causing coughing.
Question 6: What are the uses of Selenic acid?
Answer:
Selenic acid is used in manufacturing of fertilizers, metal refining, protecting steel parts from rust and also used in toilet cleaning, drain cleaning.