Metals And Reactivity Series

Question 1

Reactions of Na and K when left in air

Answer 1

These soft metals can be cut easily with knife to give a shiny surface which quickly tarnishes

Question 2

Reactions of K and Na when heated in air

Answer 2

Burns with a lilac flame, forming a white solid

Burns with a yellow/orange flame, forming a white solid

Question 3

Reactions of Ca, Mg, Al, Zn when left in air

Answer 3

Reacts slowly with the air forming a layer of oxide

Question 4

Ca when heated in air

Answer 4

Burns with a brick red flame, leaving a white solid

Question 5

Mg reacted when heated in air

Answer 5

Burns with a bright white flame leaving a white ash

Question 6

Al reaction when heated in air

Answer 6

Sheets of aluminium do not burn easily. Powdered aluminium burns with white peaks leaving a white solid

Question 7

Zn reaction when heated in air

Answer 7

Burns steadily, forming a yellow solid which when cooled changes to white

Question 8

Reactions Fe and Cu when left in air

Answer 8

Oxide layer is easily rubbed off

Question 9

Fe heated in air

Answer 9

Sheets of iron do not burn easily. Iron wool or iron filings burn with yellow/orange sparks forming a black solid

Question 10

Cu heated in air

Answer 10

Sheets of red brown copper glows red and forms a black layer of copper oxide but does not burn. There may be a blue - green flame observed

Question 11

Na reaction with water

Answer 11

Floats, moves rapidly around the surface. So much heat is released that Na melts and forms a sphere of molten metal

Question 12

General equation for metal and water

Answer 12

Metal + water —> metal hydroxide + hydrogen

Question 13

K reaction with water

Answer 13

Floats, moves rapidly around the surface. Bursts into lilac flame. Bubbles of gas released. Colourless solution formed. Heat is released. Potassium disappears at the end.

Question 14

Further tests for K

Answer 14

Solution changes Universal Indicator from green to blue.

Question 15

Ca reaction with water

Answer 15

Ca granules will sink initially then rises. Bubbles of gas evolved. Beaker feels warm to the touch as heat is evolved. Calcium disappears. Colourless solution with a white ppt (due to Ca(OH)2 which is only slightly soluble).

Question 16

Mg reaction with water

Answer 16

Very few bubbles are observed even after leaving for several days.

Question 17

Al, Fe, Zn and Cu reaction with water

Answer 17

No reaction

Iron will rust after a few days

Question 18

General equation for reaction between water and metal

Answer 18

METAL + WATER —>METAL HYDROXIDE + HYDROGEN

Question 19

Mg reaction with steam

Answer 19

Reacts when heated. Produces a very bright white light. Heat given out. A white powder remains.

Question 20

Al reaction with steam

Answer 20

Aluminium foil will not react. Small pieces will react when the oxide layer is taken off. Aluminium powder reacts when heated to form a white powder. Heat is given out.

Question 21

Zn reaction with steam

Answer 21

Reacts when heated. Glows as steam is passed over producing a yellow powder. Heat is given out. Yellow powder becomes white when it is left to cool.

Question 22

Fe reaction with steam

Answer 22

Iron must be heated until it glows red before the steam is passed over. Reacts to form a black solid.

Question 23

General equation for metal and steam

Answer 23

METAL + STEAM —> METAL OXIDE + HYDROGEN

Question 24

Does copper react with water or steam?

Answer 24

Copper does not react with cold water or steam. It is used in plumbing.
Also metals below copper in the reactivity series, for example, silver and gold do not react with cold water or steam.

Question 25

Mnemonic for reactivity series

Answer 25

``` Please - K Send- Na Little - Li Charlie's - Ca Monkeys - Mg And - Al Coloured - C Zebras - Zinc In - Fe Tin - Sn Cages - Cu Securely - Ag Guarded - Au ```

Question 26

Write the half equation for this : Symbol equation Zn + 2HCl —> ZnCl2 + H2

Answer 26

Zn —> Zn 2+ + 2e-

Question 27

Write the half equation for this | Symbol equation 2Mg + O2 —> 2MgO

Answer 27

Mg —> Mg 2+ + 2e-

Question 28

Explain what happens to the calcium atoms in the reaction of water and metal in terms of electrons.

Answer 28

The calcium atoms lose electrons

Question 29

Write half equations for sodium and potassium

Answer 29

Na—> Na+ +e- | K —> K+ +e-

Question 30

Define a displacement reaction

Answer 30

A displacement reaction is one where a more reactive element displaces a less reactive element from its compound.

Question 31

Describe the beginning and end of an experiment using copper and silver nitrate

Answer 31

Beginning - Orange-brown copper wire placed in colourless solution. End - The solution turns blue and the copper wire is coated with silver crystals.

Question 32

Describe the colour changes in these displacement reactions magnesium + copper (II) sulfate magnesium + iron (II) sulfate iron + zinc sulfate iron + copper (II) sulfate zinc + copper(II) sulfate zinc + magnesium sulfate

Answer 32

blue solution turned colourless and a solid formed. pale green solution turned colourless and a solid formed no reaction blue solution went pale green and a solid formed. blue solution turned colourless and a solid formed. no reaction

Question 33

Which one of the four metals above forms a black layer of metal oxide when it is strongly heated in the air?

Answer 33

Copper forms a black layer of copper oxide when it is strongly heated in the air.

Question 34

Define ore

Answer 34

Definition : An ore is a rock that contains a metal compound from which the metal can be extracted.

Question 35

Two methods of extraction to obtain metals from ores:

Answer 35

Electrolysis | Reduction using carbon

Question 36

Define phytomining

Answer 36

Phytomining is the use of plants to absorb metal compounds from soil as part of metal extraction.

Question 37

Describe the process of phytomining (6)

Answer 37

- Some plants such as rapeseed are very good at absorbing metal compounds from the ground through their roots. - These plants are grown on ground that contains low-grade ores, and so the metal is removed from the ore and enters the plant. - The plants are harvested, dried and then burned to produce an ash, which is rich in metal compounds. - An acid such as sulfuric acid is added to the ash and insoluble metal compounds react to produce a solution containing soluble copper compounds. - The solution is called a ‘leachate’. - The metal can then be obtained by adding scrap iron to the leachate solution, and a displacement reaction will occur

Question 38

What is the solution containing soluble metal compounds produced from phytomining called?

Answer 38

leachate

Question 39

Name two disadvantages for traditional methods

Answer 39

Traditional methods involve digging, moving and disposing of large quantities of rock. - This involves noise and dust pollution, and uses large amounts of energy to move and transport the rock.

Question 40

Explain how the reactivity of metals is related to the tendency of a metal to form its positive ion

Answer 40

The reactivity of a metal depends on the tendency of the metal to lose outer shell electrons and form its positive ion The greater the tendency to lose outer shell electrons the more reactive the metal

Question 40

explain and describe the displacement reactions of metals with other metal ions in solution (4)

Answer 40

- When solid Metal compounds are heated with a solid metal, a displacement reaction can occur - This is a redox reaction - They are carried out in a crucible where both the metal and metal oxide are in powder form to increase contact between them - The further apart the metals in the reactivity series the faster and more exothermic the reaction

Question 40

How are metals high in the reactivity series extracted from metal ores ?

Answer 40

Metals high in the reactivity series are extracted by electrolysis

Question 41

How are metals low in the reactivity series removed from their ores ?

Answer 41

Reduction with carbon or carbon monoxide

Question 42

Which metals are extracted by electrolysis

Answer 42

Aluminium and metals above it

Question 43

Equation for reaction between scrap iron and copper ii Sulfate

Answer 43

Fe + CuSO4 —> FeSO4 + Cu

Question 44

Two advantages to phytomining

Answer 44

- Its less destructive than traditional mining methods | - Carbon dioxide is absorbed as the plants grow

Question 45

Disadvantages of phytomining (2)

Answer 45

- It is a slow process – time is needed for plants to grow | - Less Copper is extracted

Question 46

How must sodium, potassium and calcium be heated in air?

Answer 46

Under very careful supervision. Reactions can be dangerous