The Floating Tin Sponge
Publication No. 12596
Create a floating tin sponge that rises to the surface upon reaction of an acidic tin(II) chloride solution with zinc. Two distinct single replacement reactions are clearly visible in this demonstration of the activity series of metals and the reactivity of metals with hydrochloric acid. Beautiful crystalline tin needles are deposited immediately on the zinc surface and aggregate to give an open, lattice-like arrangement that resembles steel wool. As hydrogen gas is released, the solution effervesces and the tin sponge gradually bobs and rises and finally floats to the surface.
Acidic tin(II) chloride solution, SnCl2 in HCl, 200 mL*
Zinc, mossy, Zn, 15 g*
Forceps or tweezers
Narrow-mouth reaction vessel (beaker or graduated cylinder)
*Materials included in kit.
Acidic tin(II) chloride is toxic and corrosive to skin and eyes. Zinc metal dust may be present at the bottom of the bottle of mossy zinc. Zinc dust can be flammable. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Please review current Safety Data Sheets for additional safety, handling and disposal information.
Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. The elemental tin sponge may be rinsed thoroughly under cold running water, dried, and discarded according to Flinn Suggested Disposal Method #26a. The remaining acidic tin(II) chloride solution may be neutralized according to Flinn Suggested Disposal Method #24b.
Student Worksheet PDF
Correlation to Next Generation Science Standards (NGSS)†
Science & Engineering PracticesDeveloping and using models
Constructing explanations and designing solutions
Disciplinary Core IdeasMS-PS1.A: Structure and Properties of Matter
MS-PS1.B: Chemical Reactions
HS-PS1.A: Structure and Properties of Matter
HS-PS1.B: Chemical Reactions
HS-PS2.B: Types of Interactions
Cause and effect
Systems and system models
Stability and change
MS-PS1-2. Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.
Answers to Questions
Mossy zinc was added to an acidic tin(II) chloride solution. Very small tin crystals began to form on the surface of the zinc. The tin formed a sponge-like substance that looks like steel wool. The sponge eventually rised to the surface of the solution.
a. Oxidation of metallic zinc and reduction of tin from the tin(II) chloride.
Zn(s) + SnCl2(aq) → Sn(s) + ZnCl2(aq)
b. Oxidation of zinc with an acid and reduction of hydrogen ions.
Zn(s) + 2HCl(aq) → H2(g) + ZnCl2(aq)
An oxidation/reduction (or “redox”) reaction occurs when one or more electrons are transferred between molecules. Oxidation refers to a loss of electrons (and rise in oxidation state), and reduction refers to a gain of electrons (and subsequent decrease in oxidation state).
Addition of mossy zinc to acidic tin(II) chloride solution results in two separate single replacement reactions. The zinc pieces are coated immediately with tin crystals that look like shiny steel wool. The solution begins to effervesce with bubbles of hydrogen gas; as hydrogen gas continues to evolve the tin sponge bobs and floats to the surface.
Summerlin, L. R. and Ealy, Jr., J. L., Chemical Demonstrations: A Sourcebook for Teachers; American Chemical Society: Washington, D.C., 1988; Vol. 1.