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Catalysis of the reaction between zinc and sulfuric acid

Class practical

Zinc reacts with sulfuric acid to produce hydrogen. The reaction is catalysed by copper. The rate of reaction can be compared by means of the rate of production of hydrogen gas bubbles.
 

Lesson organisation


This is a quick and easy experiment that can be done individually or in pairs.

Chemicals

Granulated zinc, a few pieces

Copper turnings or powder, a few pieces/half a spatula

Dilute sulfuric acid, 1 M (IRRITANT), 15 cm3

Copper(II) sulfate(VI) solution, 0.5 M, a few cm3

Refer to Health & Safety and Technical notes section below for additional information.

Apparatus

Eye protection

Each student or pair of students will require:

Test-tubes, 3

Test-tube rack

Measuring cylinder (10 cm3)

Dropping pipette 

Health & Safety and Technical notes


Read our standard health & safety guidance

Dilute sulfuric acid, H2SO4(aq) (IRRITANT) - see CLEAPSS Hazcard, CLEAPSS Recipe Book and CLEAPSS L195 'Safer chemicals, safer reactions'. 

Copper(II) sulfate(VI) solution, CuSO4(aq) - see CLEAPSS Hazcard and CLEAPSS Recipe Book. 

Procedure


a Put a few pieces of granulated zinc into each of the three test-tubes. Try to have approximately the same amount in each test-tube.

b Add 5 cm3 of dilute sulfuric acid to test-tube 1. Note the rate of production of gas bubbles.

c Add a few copper turnings to test-tube 2. Make sure they are in contact with the zinc. Add 5 cm3 of dilute sulfuric acid and note the rate of production of gas bubbles.

d Add 5 cm3 of dilute sulfuric acid to test-tube 3. Then add about 1 cm3 of the copper sulfate solution using a dropping pipette. Note the rate of production of gas bubbles. Note what happens to the colour of the copper sulfate solution. Note what happens to the surface of the pieces of zinc.

Teaching notes


If the granulated zinc pieces are shiny then the reaction in test-tube 1 is slow. The reaction may be faster if the zinc is not very pure. Bubbles of hydrogen form on the surface of the zinc. The reaction is:

Zinc + Sulfuric acid → Zinc sulfate + Hydrogen
Zn(s) + H2SO4(aq)→ ZnSO4(aq)+ H2(g)

In test-tube 2, copper is the catalyst for the reaction, and the reaction should be faster than in test-tube 1, but may not be as fast as test-tube 3.

In test-tube 3, zinc displaces copper from the copper sulfate solution and the surface of the zinc goes black. The displaced copper metal then acts as a catalyst for the reaction.

Zinc + Copper sulfate → Zinc sulfate + Copper
Zn(s) + CuSO4 (aq) → ZnSO4(aq)+ Cu(s)

There may be enough hydrogen produced in test-tube 3 for students to test for using a lighted splint.

Health and Safety checked October 2007 

 

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Page last updated on 22 December 2011