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07  Indirect electron transfer from zinc to copper ions: Galvanic cell microscale
"A Daniell element  is a special Galvanic cell named after Luigi Galvani  consisting of two containers ("half-cells") with different metals in solutions of their salts. They are connected by a salt bridge
In the following experiment two half cells dip into a barrel pipette head with 1 molar potassium chloride solution as salt bridge (Fig. 2).
The half cells consist of two plastic pipette tips. Their narrow ends are closed by porous cotton wool.  2 different metals (Zn , Cu) are surrounded by 1 molar solutions of their salts (Zn- and copper(II) sulfate). The metals are connected by a multimeter to measure the potential (Fig. 2). 
Material (Fig. 1)
Material
Tray, 2 plastic pipette tips (1), head of a barrel pipette, digital multimeter (3), red and blue wire with crocodile clips (4), cotton wool (5),  scissors (6),  1M solutions of zinc sulphate (7), potassium chloride (8), copper sulphate (9), zinc coated wire (Zn), copper wire (Cu), stand (packing of vacutainers).
Experiment (compare: microscalingBradleyE.html)
1. Close the narrow ends of the pipette tips by a tiny piece of cotton wool.
2. Cut off the head of a barrel pipette.
3. Add 1 mL of potassium chloride solution.
4. Dip the pipette tips into the liquid until it has penetrated the cotton wool.
5. Add 1M ZnSO₄ and CuSO₄ solutions to the half cells without air bubbles (Use pipettes with tubes prepared as capillaries).
6. Connect the Zn and the Cu wires with the multimeter (go for 20 V DC, connect Zn with the COM terminal and Cu with the V terminal).
7. Dip the wires into the solutions of their salts (Fig. 2).
Observation
The multimeter shows a potential of 1.07 V between Zn (anode) and the Cu half cell (cathode).
Explanation (Fig. 3)
As an electron donor zinc pushes electrons through the wire to the copper electrode. Zn ions are dissolved.
The copper ions are reduced:   Zn(s) + Cu²⁺(aq) ----indirect redox reaction---> Zn²⁺(aq) + Cu(s)
Negative sulfate ions are flowing to the zinc half cell via well.
The standard rduction potentials of the two half-reactions  Zn --> Zn²⁺ + 2e-        Cu²⁺ + 2e- --> Cu   are
- 0.76 V  and + 0.34 V = 1.1 V.
Galvanic cell smallscale