Doc Brown's GCSE/IGCSE Science-Chemistry Revision Questions

Q ANSWERS! * Detailed GCSE notes on the Reactivity Series of Metals, corrosion and redox chemistry

Some formulae to help: aluminium oxide Al₂O₃ , copper(II) oxide CuO , copper(II) carbonate CuCO₃

iron(III) oxide Fe₂O₃ , iron(II) sulfate FeSO₄ , hydrogen H₂

sulfuric acid H₂SO₄ , sodium hydroxide NaOH , magnesium hydroxide Mg(OH)₂

USEFUL LINKS: Metal reactivity * Metal extraction * Transition Metals * More Industrial Chemistry of Metals

1. (a) Describe everything you expect to see when sodium is added to water containing universal indicator.

(b) Name the two chemical products of sodium reacting with water and give the symbol equation for the reaction of sodium with water.

2. (a) Describe the test and result for the gas produced in the reaction between calcium and cold water. (b) give the symbol equation for magnesium reacting with cold water.

3. (a) Describe what happens when magnesium is heated strongly in oxygen and give equation.

(b) when strongly heated in air, copper forms a black solid. What is the solid?

4. What happens when the product of burning sodium is added to water containing universal indicator and named the product formed in water.

5. (a) Give three observations that could be made when magnesium reacts with sulphuric acid.

(b) Give the word and symbol equation for zinc reacting with sulphuric acid.

(c) Give the test, and result, for the gas formed in the reaction between a metal and the acid.

(d) From copper, iron, magnesium and zinc: Which reacts with acid (i) fastest?, (ii) slowest?

6. (a) What substances must be in contact with iron before it will rust?

(b) What is the chemical structure of rust? (name and formula) and explain why it is an example of oxidation.

(c) Car bodies can be doubly protected from rusting with paint and galvanising. Describe and explain the two methods. Will the car body automatically rust if it is deeply scratched? explain your answer.

(d) Blocks of magnesium are bolted to a ships hull. Explain how this reduces steel corrosion. Why must there be no paint between the magnesium and the steel hull?

7. (a) Give three observations that could be made after adding zinc to copper(II) sulphate solution.

(b) give the symbol equation for the reaction between zinc and copper(II) sulphate solution.

(c) explain why this is an example of a displacement reaction.

(d) give the ionic equation for the reaction between zinc and copper(II) sulphate solution and explain the reaction in terms of oxidation, reduction and electron transfer.

. Copper(II) carbonate is heated with carbon powder. (i) The green carbonate powder changes to a black powder at first, and (ii) after further strong heating, reddish-brown bits of a metal are formed.

(a) Describe with the aid of symbol equations what is happening in stage (i) and stage (ii).

(b) Why is stage (i) called a thermal decomposition? and stage (ii) called a reduction reaction?

9. A mixture of aluminium powder and iron(III) oxide is made and a magnesium strip placed in it.

(a) describe what happens after the magnesium fuse is ignited and what do the products look like.

(b) Give the symbol equation for the reaction and explain it in terms of oxidation and reduction.

(c) Mg + CuO ==> ??? Will these two react on heating Y/N? explain your answer.

(d) Given part of the metal reactivity series: (high) sodium magnesium zinc iron copper gold (low)

(i) where should hydrogen be placed? and explain why?

(ii) give a full equation to show iron dissolving in dilute sulphuric acid and name the products.

(iii) give the ionic equation to show iron dissolving in any acid.

(iv) why is gold found as the pure element?

10. balance and complete the following equations

(a ) Fe + O₂ ==> Fe₃O₄

(b) Mg + O₂ ==>

(c) Fe₂(SO₄)₃ + Zn ==>

(Some formulae to help: Al₂O₃ , CuO , CuCO₃ , Fe₂O₃ , FeSO₄ , H₂ , H₂SO₄ , NaOH , Mg(OH)₂)

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