--- title: "Preparing a double salt: Mohr's salt or potash alum Template | MolDraw" url: https://www.moldraw.com/templates/setup-double-salt/ description: "Preparing a double salt: Mohr's salt or potash alum template: CBSE / ISC class 12: equimolar FeSO₄·7H₂O and (NH₄)₂SO₄ (or K₂SO₄ and Al₂(SO₄)₃·18H₂O) in warm…" lang: en publisher: Scidart Academy generated: 2026-10-28 --- [MolDraw](https://www.moldraw.com/) › [Templates](https://www.moldraw.com/templates/) › [Reaction setups](https://www.moldraw.com/templates/reaction-setups/) › Preparing a double salt: Mohr's salt or potash alum [Reaction setups](https://www.moldraw.com/templates/reaction-setups/)Premium # Preparing a double salt: Mohr's salt or potash alum template ![Preparing a double salt: Mohr's salt or potash alum template: CBSE / ISC class 12: equimolar FeSO₄·7H₂O and (NH₄)₂SO₄ (or K₂SO₄ and Al₂(SO₄)₃·18H₂O) in warm water with a little dilute H₂SO₄, concentrated in a china dish on a tripod and gauze, then cooled slowly to crystallise.](https://www.moldraw.com/templates/setup-double-salt.webp) [Edit in MolDraw](https://www.moldraw.com/)Download with Pro Premium template. Preview and edit it free in MolDraw; downloading and exporting it is part of [MolDraw Pro](https://www.moldraw.com/pricing). CBSE / ISC class 12: equimolar FeSO₄·7H₂O and (NH₄)₂SO₄ (or K₂SO₄ and Al₂(SO₄)₃·18H₂O) in warm water with a little dilute H₂SO₄, concentrated in a china dish on a tripod and gauze, then cooled slowly to crystallise. ## What the template shows - Crystallise two sulfates together from one solution - Glass rod - Crystallisation point: a drop on the rod forms crystals as it cools - China dish - Mohr's salt: 7 g FeSO₄·7H₂O + 3.5 g (NH₄)₂SO₄. Potash alum: 2.5 g K₂SO₄ + 10 g Al₂(SO₄)₃·18H₂O - Dissolve, filter, heat gently - About 20 cm³ warm water with 1–2 cm³ dilute H₂SO₄ to stop hydrolysis. Overheating oxidises Fe²⁺ (yellow) - Cool slowly - Covered and undisturbed, for large crystals - Mohr's salt FeSO₄·(NH₄)₂SO₄·6H₂O: pale green. Potash alum K₂SO₄·Al₂(SO₄)₃·24H₂O: colourless octahedra. Decant, wash with a little cold water, dry between filter papers - Reaction setup Drawn with 14 shapes – every one editable in MolDraw. ## Sources - [Housecroft & Sharpe, Inorganic Chemistry, 5th ed., Pearson 2018](https://openlibrary.org/isbn/9781292134147) Textbook ## How to use this template 1. Press **Edit in MolDraw**. The template opens on the canvas of the free MolDraw editor. 2. Change anything: move structures, edit atoms and labels, recolour highlights or delete what you do not need. 3. Add your own structures, arrows and text next to it, or combine several templates on one page. 4. Export the drawing as PNG, SVG or PDF for slides, worksheets, theses and papers. ## Frequently asked questions ### Is the Preparing a double salt: Mohr's salt or potash alum template free? You can preview the Preparing a double salt: Mohr's salt or potash alum template here and open and edit it in MolDraw for free. Downloading or exporting it is part of MolDraw Pro, together with the other premium templates. ### Can I edit the Preparing a double salt: Mohr's salt or potash alum template? Yes. It opens as an ordinary MolDraw drawing, so every structure, arrow, label and colour can be changed, and you can add your own content around it. ### Is the chemistry checked? Every structure is checked with RDKit and every curly arrow passes MolDraw’s electron-flow audit. The sources used are listed on this page. ### Can I edit the glassware? Yes. 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