Nickel(II) Sulfate
Properties
| State | Solid (crystalline) |
| Color | Yellow-green (anhydrous); emerald green (hexahydrate) |
| Solubility | Highly soluble in water (650 g/L at 20°C) |
| Melting Point | 840°C (anhydrous, decomposes) |
| Boiling Point | Decomposes before boiling |
About Nickel(II) Sulfate
Nickel(II) sulfate is the workhorse nickel salt of industry — formula NiSO4, molar mass 154.756 g/mol for the anhydrous form, though you almost never see it anhydrous outside of a calcination furnace. The hexahydrate (NiSO4·6H2O) and heptahydrate (NiSO4·7H2O) are the practical forms, both emerald-green crystals that are extremely water-soluble (650 g/L at 20°C). The compound dominates two industries: nickel electroplating and lithium-ion batteries. In a Watts plating bath, NiSO4·6H2O supplies the bulk of the dissolved nickel — typically 240–340 g/L — with smaller amounts of NiCl2·6H2O for anode activation and boric acid as a pH buffer near 4. The bath runs at 45–60°C and 3–5 A/dm² to deposit decorative-bright or sulfamate-tough nickel onto steel, brass, and zinc die-castings — the matte gray under the chrome on your faucet, the corrosion-resistant flash on copper PCBs, the satin finish inside a tubular musical instrument. The other application is the one rewriting global mining maps: NiSO4 is the precursor for the precipitated mixed hydroxide that becomes the NMC and NCA cathode in every electric-vehicle battery built today, and battery-grade NiSO4 demand is driving roughly $40 billion of new mining and refining capacity in Indonesia, the Philippines, and Australia. NiSO4 is produced by dissolving nickel metal, NiO, or Ni(OH)2 in dilute sulfuric acid.
Where you'll encounter it
If you've ever held a chrome-plated bumper, the bright nickel layer underneath came out of a NiSO4-based Watts bath running 24/7 in a plating shop somewhere — chrome doesn't actually adhere to steel, the bright nickel does, and the chrome is just a 0.25 µm flash on top for color and tarnish resistance. In an analytical lab, NiSO4 is what you grab when you need a soluble Ni²⁺ standard for atomic absorption or ICP-OES calibration. The teaching demo most chemistry undergrads remember is dimethylglyoxime: add a drop of DMG reagent to a Ni²⁺ solution made from NiSO4 and you get a bright cherry-red precipitate that's the textbook example of a chelate complex and the first quantitative test most students perform. Battery industry estimates put NMC cathode demand at over 2 million tonnes per year by 2030, every gram of nickel in those cathodes passes through NiSO4 first.
Common Uses
- Bulk nickel source in Watts electroplating baths at 240-340 g/L for decorative and engineering plating
- Battery-grade precursor for NMC and NCA cathode active materials in lithium-ion EV cells
- Sulfamate nickel bath component for electroforming low-stress thick nickel deposits
- Soluble Ni²⁺ standard for AA, ICP-OES, and ICP-MS instrument calibration
- Reagent in the dimethylglyoxime gravimetric test for nickel determination
- Mordant in the dyeing of wool and nylon with nickel-complex acid dyes
- Catalyst precursor for nickel-on-silica hydrogenation catalysts in fine-chemical synthesis
Safety Information
GHS classifications: H302 + H332 (harmful if swallowed or inhaled), H315 (skin irritation), H317 (skin sensitization), H334 (respiratory sensitization), H341 (suspected mutagen), H350i (carcinogenic by inhalation), H360D (reproductive toxicity, may damage unborn child), H372 (organ damage with prolonged exposure), H410 (very toxic to aquatic life). IARC Group 1 carcinogen. Occupational exposure limits for soluble nickel compounds are expressed as elemental Ni and are among the lowest applied to common bench salts. EU REACH classifies nickel sulfate as a substance of very high concern (SVHC) for reproductive toxicity. Most common cause of allergic contact dermatitis worldwide. Handle with nitrile gloves, lab coat, splash goggles; weigh in a fume hood. Plating-bath aerosols require local exhaust ventilation and respirator protection. All waste must be collected as heavy-metal hazardous waste.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals. We deliberately do not publish occupational exposure limits or other regulatory thresholds: those values are revised over time and differ between jurisdictions, so the only correct source is the current SDS and the regulations that apply where you work.