reactivity series

Question 1

what is the order of reactivity?

Answer 1

potassium, sodium, lithium, calcium, magnesium, aluminium, (carbon), zinc, iron, (hydrogen), copper, silver, gold

(pot - sod - lit, call ma al(an)!!, (she’s) Zi(h)c, silver, gold

Question 2

what are competition reactions?

Answer 2

reactions involving metals and metal oxides

Question 3

describe a practical where you can see the displacement reaction involving metal oxides

Answer 3

1. mix magnesium powder and copper (II) oxide together and heat strongly
2. use a bunsen burner, tripod with gauze on top, ceramic paper (which has the mixture on top)
3. a violent reaction takes place
4. traces of white magnesium oxide are left on the seramic paper
5. Mg (s) + CuO (s) -> MgO (s) + Cu (s)
6. the less reactive metal, copper was displaced

Question 4

why is carbon included in the reactivity series?

Answer 4

because it is important in extracting several metals (including iron) from metal oxides as carbon displaces any metal below it

Question 5

what is the acronym for a redox reaction?

Answer 5

O xidation
I s
L oss (of electrons)
R eduction
I s
G ain (of electrons)

Question 6

give me an example of the ionic equation with copper sulphate and zinc. what is the ionic half equation? what is reduced what is oxidised?

Answer 6

Zn (s) + Cu 2+ (aq) -> Zn 2+ (aq) + Cu (s)
- Zn (s) -> Zn 2+ (aq) + 2e- OXIDATION
- Cu 2+ (aq) + 2e- -> Cu (s) REDUCTION

Question 7

what colour change takes place when zinc is added to copper sulfate

Answer 7

blue to colourless

Question 8

how can we use water to explain/ show reactivity of metals?

Answer 8

metals above hydrogen react with water (or steam) to produce hydrogen.
as you move down the reactivity scale, the reaction becomes less and less vigorous
metals below hydrogen in the reactivity such as copper don’t react with water or steam.

Question 9

what happens if a metal reacts with cold water?

Answer 9

metal + cold water -> metal hydroxide + hydrogen

Question 10

what happens if a metal reacts with steam water?

Answer 10

metal + cold water -> metal oxide + hydrogen

Question 11

describe what happens in a reaction with calcium

Answer 11

• it reacts gently with cold water
• the grey granules sink, but are carried back to the surface again as bubbles of hydrogen are formed around them
• the mixture becomes warm as heat is produced
• calcium hydroxide is formed - some of it dissolves to give a colourless solution, but most of it is left as a white insoluble solid
  Ca (s) + 2H2o (l) -> Ca (OH)2 (aq or s) + H2 (g)

Question 12

what happens when magnesium and cold water react? explain why.

Answer 12

basically nothing unless the magnesium is super clean and a few bubbles of hydrogen form on it (but the reaction quickly stops).
this is because magnesium becomes coated with insoluble magnesium hydroxide which prevents any more water from coming into contact with the magnesium

Question 13

why doesn’t aluminium really react with water?

Answer 13

this is because it is covered in a thin layer of aluminium oxide

Question 14

what is the reaction of magnesium with steam? how would you go about doing this?

Answer 14

1. put magnesium ribbon in a delivery tube with mineral wool soaked in water on the bottom. it is horizontal. place the tube above a bunsen burner (magnesium directly above heat)
2. dont heat mineral wool directly. enough heat moves back along the test tube to turn the water into steam.
3. the magnesium burns with a bright white flame in the steam, producing hydrogen, which can be ignited at the end of the delivery tube.
4. White magnesium oxide is formed
   Mg (s) + H2O (g) -> MgO (s) + H2 (g)

Question 15

what happens when zinc or iron is reacted with steam? how would you go about this?

Answer 15

1. set up a delivery tube that is horizontal. it should have mineral wool soaked in water. it should have the powdered metal or metal granules in the middle. there should be a bunsen burner under the metal, acting as a source of heat. the tube should be connected to a beaker filled with cold water. the tube connecting these two things also has a beaker on top of it to collect hydrogen. look at pg. 151 for reference
   the soaked mineral water will started to evaporate, casuing the metal to react.
2. with zinc, hydrogen is formed. this is yellow when hot but white on cooling.
   Zn (s) + H2O (g) -> ZnO (s) + H2 (g)
3. with iron, the iron becomes slightly darker grey and a complicated oxide is formed called tri-iron tetroxide (Fe3O4)
   3Fe(s) +4H2O (g) -> Fe3O4 (s) + 4H2 (g)

Question 16

what is H2O (g)?

Answer 16

steam

Question 17

how can we see the arrangement of metal reactivity with dilute HCl or H2SO4?

Answer 17

metals above hydrogen react with acids to form a salt (e.g. magnesium sulphate, zinc chloride). the higher up the metal, the more vigorous the reactions

Question 18

what does metal + acid make?

Answer 18

metal + acid -> salt + hydrogen

Question 19

what does metal + dilute sulphuric acid make?

Answer 19

metal + dilute sulphuric acid -> metal sulphate + hydrogen

Question 20

what does metal + dilute hydrochloric acid make?

Answer 20

metal + dilute hydrochloric acid -> metal chloride + hydrogen

Question 21

do metals below hydrogen react w dilute acids?

Answer 21

no

Question 22

can K, Na, Li, Ca be added to dilute acids?

Answer 22

yeah but not rlly because the reactions are too aggressive and violent. only calcium can be used it it’s rlly rlly dilute

Question 23

how does magnesium react w dilute acids? what is the equation?

Answer 23

Magnesium reacts vigorously with cold dilute acids, and the mixture becomes hot. A colourless solution of magnesium sulfate or chloride is formed. With dilute sulfuric acid:
Mg(s) + H,SO (aq) → MgSO (aq) + H2(g)

Question 24

how does aluminium react w dilute acids? what is the equation?

Answer 24

Aluminium is slow to start reacting, but after warming it reacts very vigorously.
There is a very thin, but very strong, layer of aluminium oxide on the surface of the aluminium, which stops the acid from getting to it. On heating, the acid removes this layer, and the aluminium can show its true reactivity. With dilute hydrochloric acid:
2AI(s) + 6HCI(aq) → 2AICl(aq) + 3H2(g)

Question 25

how does zinc and iron react w dilute acids? what is the equation?

Answer 25

Zine and iron react slowly in the cold, but more rapidly on heating. The vigour of the reactions is less than that of aluminium. The zinc forms zinc sulfate or zinc chloride and hydrogen. The iron forms iron(Il) sulfate or iron(Il) chloride and hydrogen. For example:
Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g)
Fe(s) + 2HC|(aq) → FeCl(aq) + H2(g)

Question 26

when iron 2+ or 3+ ions reacts w dilute acid, what is the result?

Answer 26

they both produce iron (II) salts containing Fe 2+ salts (does this make any sense? no! but the textbook said so, so like yeah - pls refer to pg 155 for any qs)

Question 27

how to find the approx. position of a metal in the reactivity series using water and dilute acids?

Answer 27

Add a very small piece of metal to some cold water. If there is any rapid reaction, then the metal must be above magnesium in the reactivity series.
If there isn’t any reaction, add a small amount of metal to some dilute hydrochloric acid (or dilute sulfuric acid). If there isn’t any reaction in the cold acid, warm it carefully.
If there is still no reaction, the metal is probably below hydrogen in the reactivity series. If there is a reaction, then it is somewhere between magnesium and hydrogen.

Question 28

Manganese (Mn) lies between aluminium and zinc in the reactivity series, and forms a 2+ ion. Solutions of manganese(Il) salts are very pale pink (almost colourless).
Use the reactivity series to predict whether manganese will react with copper(Il) sulfate solution. If it will react, describe what you would see, name the products and write an equation for the reaction.
Explain why you would expect manganese to react with steam. Name the products of the reaction and write the equation.

Answer 28

The reaction between manganese and copperI) sulfate solution
Manganese is above copper in the reactivity series and so will displace it from the copperIl) sulfate:
A pink-brown deposit of copper will be formed. The colour of the solution will fade from blue and leave a very pale pink (virtually colourless) solution of manganesell) sulfate.
Mn(s) + CuSO(aq) → MnSO(aq) + Cu(s)
b The reaction between manganese and steam
Manganese is above hydrogen in the reactivity series and so reacts with steam to give hydrogen and the metal oxide, in this case manganesell) oxide.
(You couldn’t predict the colour of the manganese(Il) oxide, and the question doesn’t ask you to do this.)
Mn(s) + H20(g) → MnO(s) + H2(g)

Question 29

when does iron rust?

Answer 29

Iron rusts in the presence of oxygen and water.

Question 30

what is affected by rusting?

Answer 30

iron and the most common alloy of iron, mild steel

Question 31

what is the formula of rust?

Answer 31

The formula of rust is Fez *XH20, where x is a variable number. It can be called ‘hydrated iron(Ill) oxide.

Question 32

why type of reaction is rusting? what happens to iron?

Answer 32

Rusting can be described as a redox reaction - the iron is oxidised. (loses electrons)

Question 33

what are the ways in which you can prevent rusting? (main ideas)

Answer 33

barrier methods, galvanizing, sacrificial protection

Question 34

what is a barrier method? What are the pros/cons?

Answer 34

• The most obvious way of preventing rusting is to keep water and oxygen away from the iron.
• You can do this by painting it, coating it in oil or grease, or covering it in plastic.
• Coating the iron with a metal below it in the reactivity series (e.g. coating steel with tin for tin cans) is also a barrier method.
• pros: usually quite cheap ways of preventing rusting
  -cons: once the coating is broken, the iron underneath is exposed to oxygen and water and the iron will rust even the bits that are not directly exposed to the air/water).

Question 35

how can you prevent rusting by galvanizing?

Answer 35

• Galvanised iron is iron that is coated with a layer of zinc. As long as the zinc layer is unscratched, it serves as a barrier to air and water.
• However, the iron still doesn’t rust, even when some of the zinc on the surface is scratched away to expose the iron.
• This is because the zinc is more reactive than iron, and so reacts with oxygen/water more readily than the iron does. The zinc corrodes instead of the iron.
• Galvanised iron doesn’t rust even in constant contact with air and water.
• it is a combination of the barrier and sacrificial method
• cons: it can be expensive, it can look a bit ugly, it can become brittle with exposure to sunlight

Question 36

how can you prevent rusting by using the sacrificial method? when is it used? give an exmaple.

Answer 36

• Zinc, magnesium or aluminium blocks are attached to metal hulls or keels of ships to prevent the iron/steel from rusting. For this to work, you have to use a metal that is more reactive than iron; the more reactive metal reacts (is oxidised) more readily in the presence of oxygen/water than the iron. The corrosion of the more reactive metal prevents the iron from rusting. Such blocks are called sacrificial anodes.
• These sacrificial anodes have to be replaced occasionally when all the more reactive metal has been oxidised. This type of protection is used on large structures where it would be very difficult to use a barrier method effectively.
• Underground pipelines are also protected using sacrificial anodes. In this case, lumps of magnesium are attached at intervals along the pipe. The very reactive magnesium corrodes in preference to the iron. The electrons produced as the magnesium forms its ions prevent the ionisation of the iron.

Question 37

what is a sacrificial anode

Answer 37

blocks attached to metal hulls or keels of ships to prevent the iron/steel from rusting. the metal used must be more reactive than iron; the more reactive metal reacts (is oxidised) more readily in the presence of oxygen/water than the iron. The corrosion of the more reactive metal prevents the iron from rusting.
Such blocks are called sacrificial anodes.