Zinc sulfide (ZnS) is a compound composed of zinc and sulfur. It is used in various applications, including luminescent materials, optoelectronics, and phosphors for LED displays.
| IUPAC Name | Zinc Sulfide |
| Molecular Formula | ZnS |
| CAS Number | 1314-98-3 |
| Synonyms | Sphalerite, Blende, Zinc Blende, Wurtzite |
| InChI | InChI=1S/S.Zn |
Zinc Sulfide Properties
Zinc Sulfide Formula
The chemical formula of zinc sulphide is ZnS, indicating its composition of zinc (Zn) and sulfur (S) atoms. This compound forms a crucial part of various industrial and scientific applications due to its unique properties.
Zinc Sulfide Molar Mass
Zinc sulphide has a molar mass of approximately 97.45 grams per mole. This value represents the combined atomic masses of the constituent zinc and sulfur atoms in a single molecule of ZnS.
Zinc Sulfide Boiling Point
Zinc sulphide does not possess a distinct boiling point because it tends to decompose rather than undergo a true boiling process when heated. This characteristic is a result of its chemical properties.
Zinc Sulfide Melting Point
Zinc sulphide has a melting point of around 1,850 degrees Celsius (3,362 degrees Fahrenheit). This high melting point makes it suitable for various high-temperature applications.
Zinc Sulfide Density g/mL
The density of zinc sulphide varies depending on its crystalline form. Generally, its density is in the range of 3.98 to 4.09 grams per cubic centimeter (g/cm³). This density range contributes to its use in optical materials.
Zinc Sulfide Molecular Weight
The molecular weight of zinc sulphide, calculated by summing the atomic masses of its components, is approximately 97.45 grams per mole. This value is crucial for determining the amount of ZnS in a given sample.
Zinc Sulfide Structure
Zinc sulphide exists in different crystal structures, primarily cubic zinc blende (also known as sphalerite) and hexagonal wurtzite forms. These arrangements of atoms determine its physical and optical properties.
Zinc Sulfide Solubility
Zinc sulphide has low solubility in water, making it practically insoluble. This characteristic is due to the strong bonds between zinc and sulfur atoms, resulting in limited dissolution in aqueous solutions. However, it can be dissolved in certain acids or alkalis under specific conditions.
| Appearance | Solid |
| Specific Gravity | 3.98 – 4.09 g/cm³ |
| Color | White, yellow, brown, black |
| Odor | Odorless |
| Molar Mass | ~97.45 g/mol |
| Density | 3.98 – 4.09 g/cm³ |
| Melting Point | ~1,850 °C (~3,362 °F) |
| Boiling Point | Decomposes |
| Flash Point | Not applicable |
| Water Solubility | Practically insoluble |
| Solubility | Soluble in acids, alkalis under specific conditions |
| Vapour Pressure | Negligible |
| Vapour Density | Not applicable |
| pKa | ~4.7 |
| pH | ~7 (neutral) |
Zinc Sulfide Safety and Hazards
Zinc sulphide poses low acute toxicity but can release toxic sulfur dioxide gas upon heating. It’s generally considered safe under normal handling. However, inhaling its dust or fumes can cause respiratory irritation. Avoid skin and eye contact. In case of exposure, rinse thoroughly and seek medical attention if irritation persists. Fire or excessive heat can lead to decomposition, releasing hazardous gases. Store away from incompatible materials. Handle with care, wear appropriate protective gear, and work in well-ventilated areas to ensure safety and prevent potential hazards associated with zinc sulphide.
| Hazard Symbols | None |
| Safety Description | Low acute toxicity; releases toxic sulfur dioxide gas upon heating; handle with care |
| UN IDs | Not applicable |
| HS Code | 2830.90.10 |
| Hazard Class | Not classified as hazardous |
| Packing Group | Not applicable |
| Toxicity | Low toxicity; respiratory irritation from dust or fumes; handle cautiously |
Zinc Sulfide Synthesis Methods
Zinc sulphide can be synthesized through various methods. One common approach involves reacting zinc oxide (ZnO) and hydrogen sulfide (H2S) gases at elevated temperatures. The reaction proceeds as follows:
ZnO (s) + H2S (g) → ZnS (s) + H2O (g)
Another method involves the reaction between zinc chloride (ZnCl2) and hydrogen sulfide gas:
ZnCl2 (aq) + H2S (g) → ZnS (s) + 2 HCl (g)
Alternatively, zinc sulphide nanoparticles can be synthesized using precipitation methods. This involves mixing soluble zinc salts with soluble sulfide salts under controlled conditions, leading to the formation of zinc sulphide nanoparticles. In some cases, organic compounds are used as capping agents to control particle size and stability.
Zinc sulphide can also be prepared by reacting zinc metal with elemental sulfur. The two substances are heated together to initiate the reaction:
Zn (s) + S (s) → ZnS (s)
These methods offer versatility in producing zinc sulphide with varying properties for different applications, such as optoelectronics, luminescent materials, and more.
Zinc Sulfide Uses
Zinc sulphide finds diverse applications across various industries due to its unique properties. Here are its notable uses:
- Optical Coatings: Zinc sulphide’s transparency in the infrared region makes it a valuable material for optical coatings, lenses, and windows in thermal imaging systems and sensors.
- Luminescent Materials: It serves as a host material for creating luminescent compounds, such as zinc sulphide doped with copper for glow-in-the-dark applications.
- Semiconductor Applications: In thin-film transistors and other semiconductor devices, zinc sulphide films play a role in electronic components.
- LED Display Phosphors: LED displays utilize zinc sulphide phosphors to enhance color and brightness.
- X-ray and Gamma-ray Detection: Scintillation detectors employ zinc sulphide’s scintillating properties to sense X-rays and gamma rays.
- Pigments and Paints: White pigments in paints, coatings, and printing inks utilize specific zinc sulphide forms such as zinc white or lithopone.
- Fluorescent Markers: In biological applications, researchers functionalize zinc sulphide nanoparticles for fluorescent markers in imaging studies.
- Solar Cells: Scientists investigate zinc sulphide nanoparticles for their potential in improving light absorption in photovoltaic solar cells.
- Catalysis: Exploring its semiconductor nature, researchers investigate zinc sulphide’s catalytic properties in various chemical reactions.
- Infrared Windows: Optical devices like cameras, telescopes, and sensors incorporate zinc sulphide for infrared windows.
The versatility of zinc sulphide arises from its ability to exhibit luminescence, transparency, and semiconductor behavior. Its tailored applications contribute significantly to fields like optics, electronics, energy, and materials science.
Questions:
Q: What is the formula for zinc sulfide?
A: The formula for zinc sulphide is ZnS.
Q: Is zinc sulfide soluble?
A: Zinc sulphide is generally insoluble in water.
Q: Is ZnS soluble in water?
A: No, ZnS is not soluble in water.
Q: Zinc sulphide is 67.1% zinc by mass. What is the mass fraction of sulfur in zinc sulfide?
A: The mass fraction of sulfur in zinc sulphide is 32.9%.
Q: How could you separate zinc chloride from zinc sulfide?
A: Zinc chloride and zinc sulphide can be separated by dissolving zinc chloride in water, leaving behind the insoluble zinc sulphide.
Q: Is zinc sulfide ionic?
A: Yes, zinc sulphide is primarily ionic.
Q: What type of stoichiometric defect is shown by ZnS?
A: Zinc sulphide can exhibit Frenkel-type stoichiometric defects.
Q: What is ZnS?
A: ZnS is the chemical formula for zinc sulphide, a compound of zinc and sulfur.
Q: What is the minimum pH required to prevent the precipitation of ZnS?
A: The minimum pH required to prevent ZnS precipitation is around 4.7.
Q: This picture shows the cubic unit cell for ZnS. How many Zn²⁺ ions are in this cubic unit cell?
A: In the cubic unit cell of ZnS, there are four Zn²⁺ ions.
Q: Is ZnS ionic or covalent?
A: ZnS is primarily considered ionic.
Q: What type of reaction is Zn + S = ZnS?
A: The reaction Zn + S = ZnS is a synthesis or combination reaction.