Chapter 15: Reactivity of metals

Question 1

Observation when a metal displaced another in a reaction (2)

Answer 1

-Coating of the displaced metal forms on the more reactive metal.
-The aqueous solution colour changes. (Becomes colourless if it was already coloured).

Question 2

Reactivity

Answer 2

the ease with which a chemical substance takes part in a chemical reaction.

Question 3

reactivity series of metals

Answer 3

an order of reactivity, giving the most reactive metal first based on results from a range of experiments involving metals reacting with O2, H2O, dilute HCl and metal salt solutions.

Question 4

The reaction of Alkali metals

Answer 4

-They all react spontaneously with water to produce hydrogen gas and metal hydroxide.
-The reactions are exothermic

Question 5

the reaction of alkali metal with air (3)

Answer 5

Li- tarnishes slowly to a give a layer of metal oxide
Na- tarnishes quickly to give a layer of oxide
K- tarnishes very quickly to give a layer of oxide

Question 6

Mg reactiion with water

Answer 6

Reacts very strongly when placed in cold water.
-Bubbles of hydrogen form very slowly o the magnesium ribbon.
-A much stronger reaction is obtained if steam is passed over heated mg.
-The Mg glows brightly to form hydrogen and Magnesium oxide.

Question 7

Lithium

Answer 7

Gas Production
Fizzes slowly
A few bubbles

The heat produced by the reaction
Moves slowly on the surface
Does not melt

Production of alkaline solution
Metal disappears slowly
The solution turns purple when tested with a universal indicator

Production of flames
No flame

Question 8

Sodium

Answer 8

Gas Production
Fizzes strongly
Many bubbles

The heat produced by the reaction
Melts into a ball on the surface and moves about
Metal disappears quickly disappears very quickly due to the heat produced being sufficient to melt it.

Production of alkaline solution
Solution turns purple

Production of flames
No flame unless held in place

Flame colour = yellow

Question 9

Potassium

Answer 9

Gas Production
Fizzes violently
A lot of bubbles

The heat produced by the reaction
Moves on the surface very quickly
Disappears very quickly due to heat produced being sufficient to melt it.
Disappears very quickly

Production of alkaline solution
Solution turns purple

Production of flames
Hydrogen ignites
A lilac flame is produced
Melts

Question 10

Ca with water

Answer 10

Reacts very quickly with cold water.

Question 11

Calcium vs Mg (2)

Answer 11

-Calcium hydroxide is more soluble than magnesium hydroxide so an alkaline solution is produced (limewater).
-As a reaction proceeds a white suspension is obtained because not all the calcium hydroxide dissolves.

Question 12

Transition metals and water

Answer 12

Morderatingly reaction metals such as u=iron or zinc react with steam like Mg but copper, silver and gold do not react with water or steam.

Question 13

dilute HCl or dilute H2SO4
mg

Answer 13

-strong reaction
bubbles of gas
magnesium disappears ‘colourless solution forms

Question 14

dilute HCl or dilute H2SO4
aluminium

Answer 14

-Slow to react in cold
-but bubbles form on heating
-aluminium disappears
-colourless solution formed.

Question 15

dilute HCl or dilute H2SO4
zinc

Answer 15

-bubbles of gas
-zinc disappears
-colourless solution forms

Question 16

dilute HCl or dilute H2SO4
iron

Answer 16

-a bubble of gas
-iron disappears
-pale-green solution formed

Question 17

dilute HCl or dilute H2SO4
copper, silver, gold

Answer 17

No reaction

Question 18

Metal + Acid —>

Answer 18

metal salt + hydrogen

Question 19

Displacement reaction

Answer 19

a reaction in which a more reactive element displaces a less reactive element from the solution of its salts

Question 20

Observation of reaction zinc and copper sulphate (3)

Answer 20

-The zinc metal gets coated with a reddish layer of copper.
-The blue colour of the solution fades and soon becomes colourless
-Zinc displaces copper from solutions so zinc is more reactive than copper.

Question 21

Observation of reaction copper and silver nitrate (3)

Answer 21

-Silver is less reactive than copper
-If copper is placed in a solution of silver nitrate then a reaction does not occur.
-A deposit of silver grows on the surface of the copper.
-The solution becomes blue because copper of the formation of copper nitrate solution.

Question 22

What are good reducing agents? (3)

Answer 22

-Reactive metals are very good reducing agents.
-They lose electrons the most easily.
-Reactive metals are those most ready to form positive ions.

Question 23

OILRIG

Answer 23

Oxidation is the loss of electrons.
Reduction is the gain of electrons.